diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..8b1e9cb
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,7 @@
+*.md
+.gitignore
+*.swp
+merge.py
+/test_*
+*.o
+run_examples
diff --git a/tests/test_7_8.c b/tests/test_7_8.c
new file mode 100644
index 0000000..3741876
--- /dev/null
+++ b/tests/test_7_8.c
@@ -0,0 +1,84 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+
+static char* read_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (!file) return NULL;
+    fseek(file, 0, SEEK_END);
+    long size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    char *content = malloc(size + 1);
+    size_t read_bytes = fread(content, 1, size, file); (void)read_bytes;
+    content[size] = '\0';
+    fclose(file);
+    return content;
+}
+
+static bool run_example(const char *filename, const char *class_name) {
+    printf("\n========================================\n");
+    printf("Running: %s\n", filename);
+    printf("========================================\n");
+
+    char *source = read_file(filename);
+    if (!source) return false;
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        free(source);
+        return false;
+    }
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        free(source);
+        return false;
+    }
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        free(source);
+        return false;
+    }
+
+    RavaVM_t *vm = rava_vm_create(program);
+    printf("\nOutput:\n");
+
+    if (!rava_vm_execute(vm, class_name, "main")) {
+        printf("\nRuntime error: %s\n", vm->error_message);
+        rava_vm_destroy(vm);
+        free(source);
+        return false;
+    }
+
+    printf("\n✅ Execution completed successfully!\n");
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+    free(source);
+
+    return true;
+}
+
+int main() {
+    run_example("examples/07_CollatzConjecture.java", "CollatzConjecture");
+    run_example("examples/08_PascalTriangle.java", "PascalTriangle");
+    return 0;
+}
diff --git a/tests/test_all_10.c b/tests/test_all_10.c
new file mode 100644
index 0000000..3990526
--- /dev/null
+++ b/tests/test_all_10.c
@@ -0,0 +1,110 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+
+static char* read_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (!file) return NULL;
+    fseek(file, 0, SEEK_END);
+    long size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    char *content = malloc(size + 1);
+    size_t read_bytes = fread(content, 1, size, file); (void)read_bytes;
+    content[size] = '\0';
+    fclose(file);
+    return content;
+}
+
+static bool run_example(const char *filename, const char *class_name) {
+    printf("\n========================================\n");
+    printf("Running: %s\n", filename);
+    printf("========================================\n");
+    fflush(stdout);
+
+    char *source = read_file(filename);
+    if (!source) return false;
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        free(source);
+        return false;
+    }
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        free(source);
+        return false;
+    }
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        free(source);
+        return false;
+    }
+
+    RavaVM_t *vm = rava_vm_create(program);
+    printf("\nOutput:\n");
+    fflush(stdout);
+
+    if (!rava_vm_execute(vm, class_name, "main")) {
+        printf("\nRuntime error: %s\n", vm->error_message);
+        rava_vm_destroy(vm);
+        free(source);
+        return false;
+    }
+
+    printf("\n✅ Execution completed successfully!\n");
+    fflush(stdout);
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+    free(source);
+
+    return true;
+}
+
+int main() {
+    const char *examples[][2] = {
+        {"examples/01_Fibonacci.java", "Fibonacci"},
+        {"examples/02_PrimeNumbers.java", "PrimeNumbers"},
+        {"examples/03_FactorialVariations.java", "FactorialVariations"},
+        {"examples/04_GCD_LCM.java", "GCD_LCM"},
+        {"examples/05_PowerFunction.java", "PowerFunction"},
+        {"examples/06_BubbleSort.java", "BubbleSort"},
+        {"examples/07_CollatzConjecture.java", "CollatzConjecture"},
+        {"examples/08_PascalTriangle.java", "PascalTriangle"},
+        {"examples/09_TowerOfHanoi.java", "TowerOfHanoi"},
+        {"examples/10_AckermannFunction.java", "AckermannFunction"},
+    };
+
+    int passed = 0;
+    for (size_t i = 0; i < 10; i++) {
+        printf("\n[%zu/10]\n", i+1);
+        fflush(stdout);
+        if (run_example(examples[i][0], examples[i][1])) {
+            passed++;
+        }
+    }
+
+    printf("\n========================================\n");
+    printf("SUMMARY: %d/10 passed\n", passed);
+    printf("========================================\n");
+    return (passed == 10) ? 0 : 1;
+}
diff --git a/tests/test_array_init.c b/tests/test_array_init.c
new file mode 100644
index 0000000..d1c6dd2
--- /dev/null
+++ b/tests/test_array_init.c
@@ -0,0 +1,125 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test_int(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error: %s\n", name, parser->error_message ? parser->error_message : "unknown");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error: %s\n", name, vm->error_message ? vm->error_message : "unknown");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== Array Initializer Tests ===\n\n");
+
+    run_test_int("simple array init",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[] arr = {1, 2, 3};\n"
+        "        return arr[0] + arr[1] + arr[2];\n"
+        "    }\n"
+        "}\n", 6);
+
+    run_test_int("array init with expressions",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[] arr = {1 + 1, 2 * 2, 3 + 3};\n"
+        "        return arr[0] + arr[1] + arr[2];\n"
+        "    }\n"
+        "}\n", 12);
+
+    run_test_int("single element array",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[] arr = {42};\n"
+        "        return arr[0];\n"
+        "    }\n"
+        "}\n", 42);
+
+    run_test_int("array init length",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[] arr = {5, 10, 15, 20};\n"
+        "        int sum = 0;\n"
+        "        for (int i = 0; i < 4; i = i + 1) {\n"
+        "            sum = sum + arr[i];\n"
+        "        }\n"
+        "        return sum;\n"
+        "    }\n"
+        "}\n", 50);
+
+    run_test_int("array init with negative values",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[] arr = {-1, -2, -3};\n"
+        "        return arr[0] + arr[1] + arr[2];\n"
+        "    }\n"
+        "}\n", -6);
+
+    run_test_int("array init with zero",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[] arr = {0, 0, 0};\n"
+        "        return arr[0] + arr[1] + arr[2];\n"
+        "    }\n"
+        "}\n", 0);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_array_init.o b/tests/test_array_init.o
new file mode 100644
index 0000000..045101d
Binary files /dev/null and b/tests/test_array_init.o differ
diff --git a/tests/test_array_syntax.c b/tests/test_array_syntax.c
new file mode 100644
index 0000000..c4de943
--- /dev/null
+++ b/tests/test_array_syntax.c
@@ -0,0 +1,30 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+int main() {
+    const char *source =
+        "public class ArrayTest {\n"
+        "    public static int main() {\n"
+        "        int[] numbers = new int[5];\n"
+        "        numbers[0] = 10;\n"
+        "        numbers[1] = 20;\n"
+        "        int result = numbers[0] + numbers[1];\n"
+        "        System.out.println(result);\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n";
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message);
+        return 1;
+    }
+
+    printf("Parsed successfully!\n");
+    return 0;
+}
diff --git a/tests/test_arrays.c b/tests/test_arrays.c
new file mode 100644
index 0000000..2373f26
--- /dev/null
+++ b/tests/test_arrays.c
@@ -0,0 +1,77 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static char* read_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (!file) return NULL;
+    fseek(file, 0, SEEK_END);
+    long size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    char *content = malloc(size + 1);
+    size_t read_bytes = fread(content, 1, size, file); (void)read_bytes;
+    content[size] = '\0';
+    fclose(file);
+    return content;
+}
+
+int main() {
+    char *source = read_file("examples/11_ArrayOperations.java");
+    if (!source) {
+        printf("Failed to read file\n");
+        return 1;
+    }
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Parse: OK\n");
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        printf("Semantic error: %s\n", analyzer->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Semantic: OK\n");
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        printf("IR generation failed\n");
+        free(source);
+        return 1;
+    }
+
+    printf("IR Gen: OK\n");
+    printf("\nOutput:\n");
+
+    RavaVM_t *vm = rava_vm_create(program);
+    if (!rava_vm_execute(vm, "ArrayOperations", "main")) {
+        printf("Runtime error: %s\n", vm->error_message);
+        rava_vm_destroy(vm);
+        free(source);
+        return 1;
+    }
+
+    printf("\nExecution: OK\n");
+
+    rava_vm_destroy(vm);
+    free(source);
+    return 0;
+}
diff --git a/tests/test_arrays.o b/tests/test_arrays.o
new file mode 100644
index 0000000..adf7611
Binary files /dev/null and b/tests/test_arrays.o differ
diff --git a/tests/test_benchmark.c b/tests/test_benchmark.c
new file mode 100644
index 0000000..9980149
--- /dev/null
+++ b/tests/test_benchmark.c
@@ -0,0 +1,64 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+static char* read_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (!file) return NULL;
+    fseek(file, 0, SEEK_END);
+    long size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    char *content = malloc(size + 1);
+    size_t read_bytes = fread(content, 1, size, file); (void)read_bytes;
+    content[size] = '\0';
+    fclose(file);
+    return content;
+}
+
+int main() {
+    char *source = read_file("examples/20_Benchmark.java");
+    if (!source) { printf("Failed to read file\n"); return 1; }
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message);
+        free(source);
+        return 1;
+    }
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        printf("Semantic error: %s\n", analyzer->error_message);
+        free(source);
+        return 1;
+    }
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        printf("IR generation failed\n");
+        free(source);
+        return 1;
+    }
+
+    RavaVM_t *vm = rava_vm_create(program);
+    if (!rava_vm_execute(vm, "Benchmark", "main")) {
+        printf("Runtime error: %s\n", vm->error_message);
+        rava_vm_destroy(vm);
+        free(source);
+        return 1;
+    }
+
+    rava_vm_destroy(vm);
+    free(source);
+    return 0;
+}
diff --git a/tests/test_bitwise.c b/tests/test_bitwise.c
new file mode 100644
index 0000000..5209db7
--- /dev/null
+++ b/tests/test_bitwise.c
@@ -0,0 +1,214 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test_int(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error: %s\n", name, parser->error_message ? parser->error_message : "unknown");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error: %s\n", name, vm->error_message ? vm->error_message : "unknown");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== Bitwise Operator Tests ===\n\n");
+
+    run_test_int("bitwise AND with vars",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int a = 12;\n"
+        "        int b = 10;\n"
+        "        return a & b;\n"
+        "    }\n"
+        "}\n", 8);
+
+    run_test_int("bitwise OR with vars",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int a = 12;\n"
+        "        int b = 10;\n"
+        "        return a | b;\n"
+        "    }\n"
+        "}\n", 14);
+
+    run_test_int("bitwise XOR",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return 12 ^ 10;\n"
+        "    }\n"
+        "}\n", 6);
+
+    run_test_int("left shift",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return 1 << 4;\n"
+        "    }\n"
+        "}\n", 16);
+
+    run_test_int("right shift",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return 16 >> 2;\n"
+        "    }\n"
+        "}\n", 4);
+
+    run_test_int("unsigned right shift",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return 16 >>> 2;\n"
+        "    }\n"
+        "}\n", 4);
+
+    run_test_int("combined bitwise ops",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int a = 5;\n"
+        "        int b = 3;\n"
+        "        return (a & b) | (a ^ b);\n"
+        "    }\n"
+        "}\n", 7);
+
+    run_test_int("shift with variable",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 2;\n"
+        "        return 1 << x;\n"
+        "    }\n"
+        "}\n", 4);
+
+    run_test_int("bitwise mask",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int value = 255;\n"
+        "        int mask = 0x0F;\n"
+        "        return value & mask;\n"
+        "    }\n"
+        "}\n", 15);
+
+    run_test_int("bit toggle with XOR",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int flags = 5;\n"
+        "        return flags ^ 1;\n"
+        "    }\n"
+        "}\n", 4);
+
+    run_test_int("bitwise NOT",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 0;\n"
+        "        return ~x;\n"
+        "    }\n"
+        "}\n", -1);
+
+    run_test_int("bitwise NOT with value",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 5;\n"
+        "        return ~x;\n"
+        "    }\n"
+        "}\n", -6);
+
+    run_test_int("compound AND assign",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 15;\n"
+        "        x &= 7;\n"
+        "        return x;\n"
+        "    }\n"
+        "}\n", 7);
+
+    run_test_int("compound OR assign",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 8;\n"
+        "        x |= 3;\n"
+        "        return x;\n"
+        "    }\n"
+        "}\n", 11);
+
+    run_test_int("compound XOR assign",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 12;\n"
+        "        x ^= 5;\n"
+        "        return x;\n"
+        "    }\n"
+        "}\n", 9);
+
+    run_test_int("compound left shift assign",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 1;\n"
+        "        x <<= 3;\n"
+        "        return x;\n"
+        "    }\n"
+        "}\n", 8);
+
+    run_test_int("compound right shift assign",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 16;\n"
+        "        x >>= 2;\n"
+        "        return x;\n"
+        "    }\n"
+        "}\n", 4);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_bitwise.o b/tests/test_bitwise.o
new file mode 100644
index 0000000..455df87
Binary files /dev/null and b/tests/test_bitwise.o differ
diff --git a/tests/test_break.c b/tests/test_break.c
new file mode 100644
index 0000000..ca783b0
--- /dev/null
+++ b/tests/test_break.c
@@ -0,0 +1,42 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+static char* read_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (!file) return NULL;
+    fseek(file, 0, SEEK_END);
+    long size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    char *content = malloc(size + 1);
+    size_t read_bytes = fread(content, 1, size, file); (void)read_bytes;
+    content[size] = '\0';
+    fclose(file);
+    return content;
+}
+
+int main() {
+    char *source = read_file("examples/19_BreakContinue.java");
+    if (!source) { printf("Failed\n"); return 1; }
+    RavaLexer_t *l = rava_lexer_create(source);
+    RavaParser_t *p = rava_parser_create(l);
+    RavaASTNode_t *ast = rava_parser_parse(p);
+    if (p->had_error) { printf("Parse: %s\n", p->error_message); return 1; }
+    printf("Parse: OK\n");
+    RavaSemanticAnalyzer_t *a = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(a, ast)) { printf("Semantic: %s\n", a->error_message); return 1; }
+    printf("Semantic: OK\n");
+    RavaIRGenerator_t *g = rava_ir_generator_create(a);
+    RavaProgram_t *prog = rava_ir_generate(g, ast);
+    if (!prog) { printf("IR failed\n"); return 1; }
+    printf("IR: OK\nOutput:\n");
+    RavaVM_t *vm = rava_vm_create(prog);
+    if (!rava_vm_execute(vm, "BreakContinue", "main")) { printf("Runtime: %s\n", vm->error_message); return 1; }
+    printf("\nExecution: OK\n");
+    return 0;
+}
diff --git a/tests/test_collections.c b/tests/test_collections.c
new file mode 100644
index 0000000..3a91558
--- /dev/null
+++ b/tests/test_collections.c
@@ -0,0 +1,278 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static int run_test(const char *name, const char *source, int expected) {
+    test_count++;
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("FAIL: %s (parse error)\n", name);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return 0;
+    }
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        printf("FAIL: %s (semantic error)\n", name);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return 0;
+    }
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        printf("FAIL: %s (IR error)\n", name);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return 0;
+    }
+
+    RavaVM_t *vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s (runtime error)\n", name);
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return 0;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int actual = rava_value_as_int(result);
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+
+    if (actual == expected) {
+        printf("PASS: %s\n", name);
+        pass_count++;
+        return 1;
+    } else {
+        printf("FAIL: %s (expected %d, got %d)\n", name, expected, actual);
+        return 0;
+    }
+}
+
+int main(void) {
+    printf("=== ArrayList Tests ===\n");
+
+    run_test("ArrayList create and size",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        ArrayList list = new ArrayList();\n"
+        "        return list.size();\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test("ArrayList add and size",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        ArrayList list = new ArrayList();\n"
+        "        list.add(10);\n"
+        "        list.add(20);\n"
+        "        list.add(30);\n"
+        "        return list.size();\n"
+        "    }\n"
+        "}\n", 3);
+
+    run_test("ArrayList add and get",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        ArrayList list = new ArrayList();\n"
+        "        list.add(42);\n"
+        "        return list.get(0);\n"
+        "    }\n"
+        "}\n", 42);
+
+    run_test("ArrayList set",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        ArrayList list = new ArrayList();\n"
+        "        list.add(10);\n"
+        "        list.set(0, 99);\n"
+        "        return list.get(0);\n"
+        "    }\n"
+        "}\n", 99);
+
+    run_test("ArrayList isEmpty true",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        ArrayList list = new ArrayList();\n"
+        "        if (list.isEmpty()) {\n"
+        "            return 1;\n"
+        "        }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 1);
+
+    run_test("ArrayList isEmpty false",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        ArrayList list = new ArrayList();\n"
+        "        list.add(1);\n"
+        "        if (list.isEmpty()) {\n"
+        "            return 1;\n"
+        "        }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test("ArrayList clear",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        ArrayList list = new ArrayList();\n"
+        "        list.add(1);\n"
+        "        list.add(2);\n"
+        "        list.clear();\n"
+        "        return list.size();\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test("ArrayList remove",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        ArrayList list = new ArrayList();\n"
+        "        list.add(10);\n"
+        "        list.add(20);\n"
+        "        list.add(30);\n"
+        "        int removed = list.remove(1);\n"
+        "        return removed;\n"
+        "    }\n"
+        "}\n", 20);
+
+    run_test("ArrayList sum elements",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        ArrayList list = new ArrayList();\n"
+        "        list.add(1);\n"
+        "        list.add(2);\n"
+        "        list.add(3);\n"
+        "        list.add(4);\n"
+        "        int sum = 0;\n"
+        "        for (int i = 0; i < list.size(); i = i + 1) {\n"
+        "            sum = sum + list.get(i);\n"
+        "        }\n"
+        "        return sum;\n"
+        "    }\n"
+        "}\n", 10);
+
+    printf("\n=== HashMap Tests ===\n");
+
+    run_test("HashMap create and size",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        HashMap map = new HashMap();\n"
+        "        return map.size();\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test("HashMap put and size",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        HashMap map = new HashMap();\n"
+        "        map.put(\"a\", 1);\n"
+        "        map.put(\"b\", 2);\n"
+        "        return map.size();\n"
+        "    }\n"
+        "}\n", 2);
+
+    run_test("HashMap put and get",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        HashMap map = new HashMap();\n"
+        "        map.put(\"key\", 42);\n"
+        "        return map.get(\"key\");\n"
+        "    }\n"
+        "}\n", 42);
+
+    run_test("HashMap containsKey true",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        HashMap map = new HashMap();\n"
+        "        map.put(\"test\", 99);\n"
+        "        if (map.containsKey(\"test\")) {\n"
+        "            return 1;\n"
+        "        }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 1);
+
+    run_test("HashMap containsKey false",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        HashMap map = new HashMap();\n"
+        "        map.put(\"test\", 99);\n"
+        "        if (map.containsKey(\"other\")) {\n"
+        "            return 1;\n"
+        "        }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test("HashMap remove",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        HashMap map = new HashMap();\n"
+        "        map.put(\"a\", 10);\n"
+        "        map.put(\"b\", 20);\n"
+        "        int removed = map.remove(\"a\");\n"
+        "        return removed + map.size();\n"
+        "    }\n"
+        "}\n", 11);
+
+    run_test("HashMap clear",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        HashMap map = new HashMap();\n"
+        "        map.put(\"x\", 1);\n"
+        "        map.put(\"y\", 2);\n"
+        "        map.clear();\n"
+        "        return map.size();\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test("HashMap update value",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        HashMap map = new HashMap();\n"
+        "        map.put(\"key\", 10);\n"
+        "        map.put(\"key\", 20);\n"
+        "        return map.get(\"key\");\n"
+        "    }\n"
+        "}\n", 20);
+
+    printf("\n=== Results ===\n");
+    printf("Passed: %d/%d\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_collections.o b/tests/test_collections.o
new file mode 100644
index 0000000..94f0d92
Binary files /dev/null and b/tests/test_collections.o differ
diff --git a/tests/test_dowhile.c b/tests/test_dowhile.c
new file mode 100644
index 0000000..b0d198c
--- /dev/null
+++ b/tests/test_dowhile.c
@@ -0,0 +1,139 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error\n", name);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error\n", name);
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== Do-While Loop Tests ===\n\n");
+
+    run_test("Simple do-while",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int i = 0;\n"
+        "        do {\n"
+        "            i = i + 1;\n"
+        "        } while (i < 5);\n"
+        "        return i;\n"
+        "    }\n"
+        "}\n", 5);
+
+    run_test("Do-while sum",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int sum = 0;\n"
+        "        int i = 1;\n"
+        "        do {\n"
+        "            sum = sum + i;\n"
+        "            i = i + 1;\n"
+        "        } while (i <= 10);\n"
+        "        return sum;\n"
+        "    }\n"
+        "}\n", 55);
+
+    run_test("Do-while executes at least once",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 0;\n"
+        "        do {\n"
+        "            x = 42;\n"
+        "        } while (false);\n"
+        "        return x;\n"
+        "    }\n"
+        "}\n", 42);
+
+    run_test("Do-while with break",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int i = 0;\n"
+        "        do {\n"
+        "            i = i + 1;\n"
+        "            if (i == 3) {\n"
+        "                break;\n"
+        "            }\n"
+        "        } while (i < 10);\n"
+        "        return i;\n"
+        "    }\n"
+        "}\n", 3);
+
+    run_test("Nested do-while",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int count = 0;\n"
+        "        int i = 0;\n"
+        "        do {\n"
+        "            int j = 0;\n"
+        "            do {\n"
+        "                count = count + 1;\n"
+        "                j = j + 1;\n"
+        "            } while (j < 3);\n"
+        "            i = i + 1;\n"
+        "        } while (i < 2);\n"
+        "        return count;\n"
+        "    }\n"
+        "}\n", 6);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_dowhile.o b/tests/test_dowhile.o
new file mode 100644
index 0000000..3da4708
Binary files /dev/null and b/tests/test_dowhile.o differ
diff --git a/tests/test_elseif.c b/tests/test_elseif.c
new file mode 100644
index 0000000..72e7706
--- /dev/null
+++ b/tests/test_elseif.c
@@ -0,0 +1,77 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static char* read_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (!file) return NULL;
+    fseek(file, 0, SEEK_END);
+    long size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    char *content = malloc(size + 1);
+    size_t read_bytes = fread(content, 1, size, file); (void)read_bytes;
+    content[size] = '\0';
+    fclose(file);
+    return content;
+}
+
+int main() {
+    char *source = read_file("examples/18_ElseIf.java");
+    if (!source) {
+        printf("Failed to read file\n");
+        return 1;
+    }
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Parse: OK\n");
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        printf("Semantic error: %s\n", analyzer->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Semantic: OK\n");
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        printf("IR generation failed\n");
+        free(source);
+        return 1;
+    }
+
+    printf("IR Gen: OK\n");
+    printf("\nOutput:\n");
+
+    RavaVM_t *vm = rava_vm_create(program);
+    if (!rava_vm_execute(vm, "ElseIf", "main")) {
+        printf("Runtime error: %s\n", vm->error_message);
+        rava_vm_destroy(vm);
+        free(source);
+        return 1;
+    }
+
+    printf("\nExecution: OK\n");
+
+    rava_vm_destroy(vm);
+    free(source);
+    return 0;
+}
diff --git a/tests/test_enhanced_for.c b/tests/test_enhanced_for.c
new file mode 100644
index 0000000..33b9a51
--- /dev/null
+++ b/tests/test_enhanced_for.c
@@ -0,0 +1,130 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test_int(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error: %s\n", name, parser->error_message ? parser->error_message : "unknown");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error: %s\n", name, vm->error_message ? vm->error_message : "unknown");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== Enhanced For Loop Tests ===\n\n");
+
+    run_test_int("sum array elements",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[] arr = new int[3];\n"
+        "        arr[0] = 1;\n"
+        "        arr[1] = 2;\n"
+        "        arr[2] = 3;\n"
+        "        int sum = 0;\n"
+        "        for (int x : arr) {\n"
+        "            sum = sum + x;\n"
+        "        }\n"
+        "        return sum;\n"
+        "    }\n"
+        "}\n", 6);
+
+    run_test_int("count elements",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[] arr = new int[5];\n"
+        "        int count = 0;\n"
+        "        for (int x : arr) {\n"
+        "            count = count + 1;\n"
+        "        }\n"
+        "        return count;\n"
+        "    }\n"
+        "}\n", 5);
+
+    run_test_int("find max",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[] arr = new int[4];\n"
+        "        arr[0] = 5;\n"
+        "        arr[1] = 9;\n"
+        "        arr[2] = 3;\n"
+        "        arr[3] = 7;\n"
+        "        int max = 0;\n"
+        "        for (int x : arr) {\n"
+        "            if (x > max) {\n"
+        "                max = x;\n"
+        "            }\n"
+        "        }\n"
+        "        return max;\n"
+        "    }\n"
+        "}\n", 9);
+
+    run_test_int("empty array",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[] arr = new int[0];\n"
+        "        int sum = 0;\n"
+        "        for (int x : arr) {\n"
+        "            sum = sum + 1;\n"
+        "        }\n"
+        "        return sum;\n"
+        "    }\n"
+        "}\n", 0);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_enhanced_for.o b/tests/test_enhanced_for.o
new file mode 100644
index 0000000..5ec7fa5
Binary files /dev/null and b/tests/test_enhanced_for.o differ
diff --git a/tests/test_enums.c b/tests/test_enums.c
new file mode 100644
index 0000000..1e38fbb
--- /dev/null
+++ b/tests/test_enums.c
@@ -0,0 +1,152 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+static int run_test(const char *name, const char *source, const char *class_name,
+                    const char *method_name, int expected) {
+    printf("Test: %-40s ... ", name);
+    fflush(stdout);
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("FAIL (parse error: %s)\n", parser->error_message);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return 0;
+    }
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        printf("FAIL (semantic error: %s)\n", analyzer->error_message);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return 0;
+    }
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        printf("FAIL (IR generation failed)\n");
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return 0;
+    }
+
+    RavaVM_t *vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, class_name, method_name)) {
+        printf("FAIL (runtime error: %s)\n", vm->error_message ? vm->error_message : "unknown");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return 0;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int result_int = rava_value_as_int(result);
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+
+    if (result_int == expected) {
+        printf("PASS (result=%d)\n", result_int);
+        return 1;
+    } else {
+        printf("FAIL (expected=%d, got=%d)\n", expected, result_int);
+        return 0;
+    }
+}
+
+int main(void) {
+    printf("=== Enum Tests ===\n\n");
+
+    int passed = 0;
+    int total = 0;
+
+    total++;
+    passed += run_test("simple enum ordinal",
+        "public enum Color { RED, GREEN, BLUE }\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return Color.RED;\n"
+        "    }\n"
+        "}\n",
+        "Test", "main", 0);
+
+    total++;
+    passed += run_test("enum second value",
+        "public enum Color { RED, GREEN, BLUE }\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return Color.GREEN;\n"
+        "    }\n"
+        "}\n",
+        "Test", "main", 1);
+
+    total++;
+    passed += run_test("enum third value",
+        "public enum Color { RED, GREEN, BLUE }\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return Color.BLUE;\n"
+        "    }\n"
+        "}\n",
+        "Test", "main", 2);
+
+    total++;
+    passed += run_test("enum comparison",
+        "public enum Day { MON, TUE, WED, THU, FRI }\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int day = Day.WED;\n"
+        "        if (day == 2) {\n"
+        "            return 42;\n"
+        "        }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n",
+        "Test", "main", 42);
+
+    total++;
+    passed += run_test("enum in switch",
+        "public enum Status { OK, ERROR, PENDING }\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int s = Status.ERROR;\n"
+        "        switch (s) {\n"
+        "            case 0: return 10;\n"
+        "            case 1: return 20;\n"
+        "            case 2: return 30;\n"
+        "            default: return 0;\n"
+        "        }\n"
+        "    }\n"
+        "}\n",
+        "Test", "main", 20);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", passed, total);
+
+    return (passed == total) ? 0 : 1;
+}
diff --git a/tests/test_enums.o b/tests/test_enums.o
new file mode 100644
index 0000000..e72d4ed
Binary files /dev/null and b/tests/test_enums.o differ
diff --git a/tests/test_exceptions.c b/tests/test_exceptions.c
new file mode 100644
index 0000000..44ecd67
--- /dev/null
+++ b/tests/test_exceptions.c
@@ -0,0 +1,127 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test_int(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error: %s\n", name, parser->error_message ? parser->error_message : "unknown");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error: %s\n", name, vm->error_message ? vm->error_message : "unknown");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== Exception Handling Tests ===\n\n");
+
+    run_test_int("basic try-catch",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int result = 0;\n"
+        "        try {\n"
+        "            throw 42;\n"
+        "        } catch (Exception e) {\n"
+        "            result = e;\n"
+        "        }\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 42);
+
+    run_test_int("try without exception",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int result = 10;\n"
+        "        try {\n"
+        "            result = 20;\n"
+        "        } catch (Exception e) {\n"
+        "            result = 99;\n"
+        "        }\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 20);
+
+    run_test_int("catch modifies value",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 5;\n"
+        "        try {\n"
+        "            throw 10;\n"
+        "        } catch (Exception e) {\n"
+        "            x = x + e;\n"
+        "        }\n"
+        "        return x;\n"
+        "    }\n"
+        "}\n", 15);
+
+    run_test_int("try-finally without exception",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int result = 0;\n"
+        "        try {\n"
+        "            result = 10;\n"
+        "        } catch (Exception e) {\n"
+        "            result = 99;\n"
+        "        } finally {\n"
+        "            result = result + 5;\n"
+        "        }\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 15);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_exceptions.o b/tests/test_exceptions.o
new file mode 100644
index 0000000..2fc7d6d
Binary files /dev/null and b/tests/test_exceptions.o differ
diff --git a/tests/test_fastframe.c b/tests/test_fastframe.c
new file mode 100644
index 0000000..e636620
--- /dev/null
+++ b/tests/test_fastframe.c
@@ -0,0 +1,142 @@
+#include <stdio.h>
+#include <assert.h>
+#include "../runtime/fastframe.h"
+
+static int tests_passed = 0;
+
+#define TEST(name) static void test_##name(void)
+#define RUN_TEST(name) do { \
+    printf("Running %s... ", #name); \
+    test_##name(); \
+    printf("PASSED\n"); \
+    tests_passed++; \
+} while(0)
+
+TEST(init) {
+    rava_fastframe_init();
+    assert(rava_fastframe_get_depth() == 0);
+    assert(rava_fastframe_current() == NULL);
+}
+
+TEST(push_pop) {
+    rava_fastframe_init();
+
+    FastFrame_t* frame = rava_fastframe_push(NULL, 4);
+    assert(frame != NULL);
+    assert(rava_fastframe_get_depth() == 1);
+    assert(rava_fastframe_current() == frame);
+
+    rava_fastframe_pop();
+    assert(rava_fastframe_get_depth() == 0);
+    assert(rava_fastframe_current() == NULL);
+}
+
+TEST(nested_frames) {
+    rava_fastframe_init();
+
+    FastFrame_t* f1 = rava_fastframe_push(NULL, 2);
+    FastFrame_t* f2 = rava_fastframe_push(NULL, 2);
+    FastFrame_t* f3 = rava_fastframe_push(NULL, 2);
+
+    assert(rava_fastframe_get_depth() == 3);
+    assert(rava_fastframe_current() == f3);
+
+    rava_fastframe_pop();
+    assert(rava_fastframe_current() == f2);
+
+    rava_fastframe_pop();
+    assert(rava_fastframe_current() == f1);
+
+    rava_fastframe_pop();
+    assert(rava_fastframe_current() == NULL);
+}
+
+TEST(stack_operations) {
+    rava_fastframe_init();
+
+    FastFrame_t* frame = rava_fastframe_push(NULL, 4);
+    assert(rava_fastframe_stack_is_empty(frame));
+
+    rava_fastframe_stack_push(frame, rava_nanbox_int(10));
+    rava_fastframe_stack_push(frame, rava_nanbox_int(20));
+    rava_fastframe_stack_push(frame, rava_nanbox_int(30));
+
+    assert(!rava_fastframe_stack_is_empty(frame));
+    assert(frame->stack_top == 3);
+
+    RavaNanboxValue_t top = rava_fastframe_stack_peek(frame);
+    assert(rava_nanbox_as_int(top) == 30);
+    assert(frame->stack_top == 3);
+
+    RavaNanboxValue_t v1 = rava_fastframe_stack_pop(frame);
+    RavaNanboxValue_t v2 = rava_fastframe_stack_pop(frame);
+    RavaNanboxValue_t v3 = rava_fastframe_stack_pop(frame);
+
+    assert(rava_nanbox_as_int(v1) == 30);
+    assert(rava_nanbox_as_int(v2) == 20);
+    assert(rava_nanbox_as_int(v3) == 10);
+    assert(rava_fastframe_stack_is_empty(frame));
+
+    rava_fastframe_reset();
+}
+
+TEST(locals) {
+    rava_fastframe_init();
+
+    FastFrame_t* frame = rava_fastframe_push(NULL, 8);
+
+    frame->locals[0] = rava_nanbox_int(100);
+    frame->locals[1] = rava_nanbox_int(200);
+    frame->locals[2] = rava_nanbox_bool(true);
+
+    assert(rava_nanbox_as_int(frame->locals[0]) == 100);
+    assert(rava_nanbox_as_int(frame->locals[1]) == 200);
+    assert(rava_nanbox_as_bool(frame->locals[2]) == true);
+
+    rava_fastframe_reset();
+}
+
+TEST(reset) {
+    rava_fastframe_init();
+
+    rava_fastframe_push(NULL, 2);
+    rava_fastframe_push(NULL, 2);
+    rava_fastframe_push(NULL, 2);
+
+    assert(rava_fastframe_get_depth() == 3);
+
+    rava_fastframe_reset();
+    assert(rava_fastframe_get_depth() == 0);
+}
+
+TEST(stack_clear) {
+    rava_fastframe_init();
+
+    FastFrame_t* frame = rava_fastframe_push(NULL, 4);
+    rava_fastframe_stack_push(frame, rava_nanbox_int(1));
+    rava_fastframe_stack_push(frame, rava_nanbox_int(2));
+    rava_fastframe_stack_push(frame, rava_nanbox_int(3));
+
+    assert(frame->stack_top == 3);
+
+    rava_fastframe_stack_clear(frame);
+    assert(frame->stack_top == 0);
+    assert(rava_fastframe_stack_is_empty(frame));
+
+    rava_fastframe_reset();
+}
+
+int main(void) {
+    printf("=== Fast Frame Unit Tests ===\n\n");
+
+    RUN_TEST(init);
+    RUN_TEST(push_pop);
+    RUN_TEST(nested_frames);
+    RUN_TEST(stack_operations);
+    RUN_TEST(locals);
+    RUN_TEST(reset);
+    RUN_TEST(stack_clear);
+
+    printf("\n=== Results: %d tests passed ===\n", tests_passed);
+    return 0;
+}
diff --git a/tests/test_fileio.c b/tests/test_fileio.c
new file mode 100644
index 0000000..6da6fa9
--- /dev/null
+++ b/tests/test_fileio.c
@@ -0,0 +1,77 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static char* read_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (!file) return NULL;
+    fseek(file, 0, SEEK_END);
+    long size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    char *content = malloc(size + 1);
+    size_t read_bytes = fread(content, 1, size, file); (void)read_bytes;
+    content[size] = '\0';
+    fclose(file);
+    return content;
+}
+
+int main() {
+    char *source = read_file("examples/15_FileIO.java");
+    if (!source) {
+        printf("Failed to read file\n");
+        return 1;
+    }
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Parse: OK\n");
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        printf("Semantic error: %s\n", analyzer->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Semantic: OK\n");
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        printf("IR generation failed\n");
+        free(source);
+        return 1;
+    }
+
+    printf("IR Gen: OK\n");
+    printf("\nOutput:\n");
+
+    RavaVM_t *vm = rava_vm_create(program);
+    if (!rava_vm_execute(vm, "FileIO", "main")) {
+        printf("Runtime error: %s\n", vm->error_message);
+        rava_vm_destroy(vm);
+        free(source);
+        return 1;
+    }
+
+    printf("\nExecution: OK\n");
+
+    rava_vm_destroy(vm);
+    free(source);
+    return 0;
+}
diff --git a/tests/test_fileio.o b/tests/test_fileio.o
new file mode 100644
index 0000000..2fb4b88
Binary files /dev/null and b/tests/test_fileio.o differ
diff --git a/tests/test_forloop.c b/tests/test_forloop.c
new file mode 100644
index 0000000..e46be99
--- /dev/null
+++ b/tests/test_forloop.c
@@ -0,0 +1,77 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static char* read_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (!file) return NULL;
+    fseek(file, 0, SEEK_END);
+    long size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    char *content = malloc(size + 1);
+    size_t read_bytes = fread(content, 1, size, file); (void)read_bytes;
+    content[size] = '\0';
+    fclose(file);
+    return content;
+}
+
+int main() {
+    char *source = read_file("examples/16_ForLoop.java");
+    if (!source) {
+        printf("Failed to read file\n");
+        return 1;
+    }
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Parse: OK\n");
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        printf("Semantic error: %s\n", analyzer->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Semantic: OK\n");
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        printf("IR generation failed\n");
+        free(source);
+        return 1;
+    }
+
+    printf("IR Gen: OK\n");
+    printf("\nOutput:\n");
+
+    RavaVM_t *vm = rava_vm_create(program);
+    if (!rava_vm_execute(vm, "ForLoop", "main")) {
+        printf("Runtime error: %s\n", vm->error_message);
+        rava_vm_destroy(vm);
+        free(source);
+        return 1;
+    }
+
+    printf("\nExecution: OK\n");
+
+    rava_vm_destroy(vm);
+    free(source);
+    return 0;
+}
diff --git a/tests/test_inheritance.c b/tests/test_inheritance.c
new file mode 100644
index 0000000..728284d
--- /dev/null
+++ b/tests/test_inheritance.c
@@ -0,0 +1,77 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static char* read_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (!file) return NULL;
+    fseek(file, 0, SEEK_END);
+    long size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    char *content = malloc(size + 1);
+    size_t read_bytes = fread(content, 1, size, file); (void)read_bytes;
+    content[size] = '\0';
+    fclose(file);
+    return content;
+}
+
+int main() {
+    char *source = read_file("examples/17_Inheritance.java");
+    if (!source) {
+        printf("Failed to read file\n");
+        return 1;
+    }
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Parse: OK\n");
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        printf("Semantic error: %s\n", analyzer->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Semantic: OK\n");
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        printf("IR generation failed\n");
+        free(source);
+        return 1;
+    }
+
+    printf("IR Gen: OK\n");
+    printf("\nOutput:\n");
+
+    RavaVM_t *vm = rava_vm_create(program);
+    if (!rava_vm_execute(vm, "Inheritance", "main")) {
+        printf("Runtime error: %s\n", vm->error_message);
+        rava_vm_destroy(vm);
+        free(source);
+        return 1;
+    }
+
+    printf("\nExecution: OK\n");
+
+    rava_vm_destroy(vm);
+    free(source);
+    return 0;
+}
diff --git a/tests/test_instance_methods.c b/tests/test_instance_methods.c
new file mode 100644
index 0000000..d127a99
--- /dev/null
+++ b/tests/test_instance_methods.c
@@ -0,0 +1,77 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static char* read_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (!file) return NULL;
+    fseek(file, 0, SEEK_END);
+    long size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    char *content = malloc(size + 1);
+    size_t read_bytes = fread(content, 1, size, file); (void)read_bytes;
+    content[size] = '\0';
+    fclose(file);
+    return content;
+}
+
+int main() {
+    char *source = read_file("examples/14_InstanceMethods.java");
+    if (!source) {
+        printf("Failed to read file\n");
+        return 1;
+    }
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Parse: OK\n");
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        printf("Semantic error: %s\n", analyzer->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Semantic: OK\n");
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        printf("IR generation failed\n");
+        free(source);
+        return 1;
+    }
+
+    printf("IR Gen: OK\n");
+    printf("\nOutput:\n");
+
+    RavaVM_t *vm = rava_vm_create(program);
+    if (!rava_vm_execute(vm, "InstanceMethods", "main")) {
+        printf("Runtime error: %s\n", vm->error_message);
+        rava_vm_destroy(vm);
+        free(source);
+        return 1;
+    }
+
+    printf("\nExecution: OK\n");
+
+    rava_vm_destroy(vm);
+    free(source);
+    return 0;
+}
diff --git a/tests/test_instance_methods.o b/tests/test_instance_methods.o
new file mode 100644
index 0000000..d2468fc
Binary files /dev/null and b/tests/test_instance_methods.o differ
diff --git a/tests/test_instanceof.c b/tests/test_instanceof.c
new file mode 100644
index 0000000..d857cf1
--- /dev/null
+++ b/tests/test_instanceof.c
@@ -0,0 +1,105 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test_int(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error: %s\n", name, parser->error_message ? parser->error_message : "unknown");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error: %s\n", name, vm->error_message ? vm->error_message : "unknown");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== Instanceof Tests ===\n\n");
+
+    run_test_int("instanceof true",
+        "public class Animal {}\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        Animal a = new Animal();\n"
+        "        if (a instanceof Animal) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 1);
+
+    run_test_int("instanceof false",
+        "public class Animal {}\n"
+        "public class Dog {}\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        Dog d = new Dog();\n"
+        "        if (d instanceof Animal) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test_int("instanceof in expression",
+        "public class Person {}\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        Person p = new Person();\n"
+        "        int result = 0;\n"
+        "        if (p instanceof Person) { result = 42; }\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 42);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_instanceof.o b/tests/test_instanceof.o
new file mode 100644
index 0000000..730ddcd
Binary files /dev/null and b/tests/test_instanceof.o differ
diff --git a/tests/test_interfaces.c b/tests/test_interfaces.c
new file mode 100644
index 0000000..f1f5f34
--- /dev/null
+++ b/tests/test_interfaces.c
@@ -0,0 +1,148 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test_int(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error: %s\n", name, parser->error_message ? parser->error_message : "unknown");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error: %s\n", name, vm->error_message ? vm->error_message : "unknown");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== Interface Tests ===\n\n");
+
+    run_test_int("interface with implementing class",
+        "interface Addable {\n"
+        "    int add(int a, int b);\n"
+        "}\n"
+        "class Calculator implements Addable {\n"
+        "    int add(int a, int b) {\n"
+        "        return a + b;\n"
+        "    }\n"
+        "}\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        Calculator calc = new Calculator();\n"
+        "        return calc.add(10, 20);\n"
+        "    }\n"
+        "}\n", 30);
+
+    run_test_int("class implements multiple interfaces",
+        "interface Addable {\n"
+        "    int add(int a, int b);\n"
+        "}\n"
+        "interface Subtractable {\n"
+        "    int subtract(int a, int b);\n"
+        "}\n"
+        "class Calculator implements Addable, Subtractable {\n"
+        "    int add(int a, int b) {\n"
+        "        return a + b;\n"
+        "    }\n"
+        "    int subtract(int a, int b) {\n"
+        "        return a - b;\n"
+        "    }\n"
+        "}\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        Calculator calc = new Calculator();\n"
+        "        return calc.add(100, 50) - calc.subtract(30, 10);\n"
+        "    }\n"
+        "}\n", 130);
+
+    run_test_int("class extends and implements",
+        "interface Printable {\n"
+        "    int getValue();\n"
+        "}\n"
+        "class Base {\n"
+        "    int baseValue;\n"
+        "    Base() {\n"
+        "        this.baseValue = 100;\n"
+        "    }\n"
+        "}\n"
+        "class Derived extends Base implements Printable {\n"
+        "    int getValue() {\n"
+        "        return this.baseValue + 50;\n"
+        "    }\n"
+        "}\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        Derived d = new Derived();\n"
+        "        return d.getValue();\n"
+        "    }\n"
+        "}\n", 150);
+
+    run_test_int("empty interface",
+        "interface Empty {\n"
+        "}\n"
+        "class MyClass implements Empty {\n"
+        "    int getValue() {\n"
+        "        return 42;\n"
+        "    }\n"
+        "}\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        MyClass obj = new MyClass();\n"
+        "        return obj.getValue();\n"
+        "    }\n"
+        "}\n", 42);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_interfaces.o b/tests/test_interfaces.o
new file mode 100644
index 0000000..3379f18
Binary files /dev/null and b/tests/test_interfaces.o differ
diff --git a/tests/test_ir.c b/tests/test_ir.c
new file mode 100644
index 0000000..a97eeab
--- /dev/null
+++ b/tests/test_ir.c
@@ -0,0 +1,66 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+int main() {
+    const char *source =
+        "public class Math {\n"
+        "    public static int add(int a, int b) {\n"
+        "        int result = a + b;\n"
+        "        return result;\n"
+        "    }\n"
+        "\n"
+        "    public static int factorial(int n) {\n"
+        "        if (n <= 1) {\n"
+        "            return 1;\n"
+        "        }\n"
+        "        return n * factorial(n - 1);\n"
+        "    }\n"
+        "}\n";
+
+    printf("Source code:\n%s\n", source);
+    printf("\nIR Generation:\n");
+    printf("================================================================================\n\n");
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message ? parser->error_message : "Unknown error");
+        return 1;
+    }
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    bool semantic_ok = rava_semantic_analyze(analyzer, ast);
+
+    if (!semantic_ok) {
+        printf("Semantic error: %s\n", analyzer->error_message ? analyzer->error_message : "Unknown error");
+        return 1;
+    }
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (program) {
+        rava_ir_print(program);
+        printf("\n✓ IR generation completed successfully!\n");
+    } else {
+        printf("✗ IR generation failed!\n");
+        return 1;
+    }
+
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+
+    printf("\nIR test completed!\n");
+    return 0;
+}
diff --git a/tests/test_ir.o b/tests/test_ir.o
new file mode 100644
index 0000000..0f81dc2
Binary files /dev/null and b/tests/test_ir.o differ
diff --git a/tests/test_labeltable.c b/tests/test_labeltable.c
new file mode 100644
index 0000000..d63419b
--- /dev/null
+++ b/tests/test_labeltable.c
@@ -0,0 +1,124 @@
+#include <stdio.h>
+#include <assert.h>
+#include <stdlib.h>
+#include "../ir/ir.h"
+#include "../runtime/labeltable.h"
+
+static int tests_passed = 0;
+
+#define TEST(name) static void test_##name(void)
+#define RUN_TEST(name) do { \
+    printf("Running %s... ", #name); \
+    test_##name(); \
+    printf("PASSED\n"); \
+    tests_passed++; \
+} while(0)
+
+TEST(create_empty) {
+    RavaInstructionList_t* list = rava_instruction_list_create();
+    LabelTable_t* table = rava_labeltable_create(list);
+    assert(table != NULL);
+    rava_labeltable_destroy(table);
+    rava_instruction_list_destroy(list);
+}
+
+TEST(create_null) {
+    LabelTable_t* table = rava_labeltable_create(NULL);
+    assert(table == NULL);
+}
+
+TEST(single_label) {
+    RavaInstructionList_t* list = rava_instruction_list_create();
+
+    RavaInstruction_t instr1 = {.opcode = RAVA_OP_LOAD_CONST, .operand.int_value = 10};
+    RavaInstruction_t instr2 = {.opcode = RAVA_OP_LABEL, .operand.label_id = 0};
+    RavaInstruction_t instr3 = {.opcode = RAVA_OP_LOAD_CONST, .operand.int_value = 20};
+
+    rava_instruction_list_add(list, instr1);
+    rava_instruction_list_add(list, instr2);
+    rava_instruction_list_add(list, instr3);
+
+    LabelTable_t* table = rava_labeltable_create(list);
+    assert(table != NULL);
+
+    size_t pc = rava_labeltable_lookup(table, 0);
+    assert(pc == 2);
+
+    rava_labeltable_destroy(table);
+    rava_instruction_list_destroy(list);
+}
+
+TEST(multiple_labels) {
+    RavaInstructionList_t* list = rava_instruction_list_create();
+
+    RavaInstruction_t instr0 = {.opcode = RAVA_OP_LOAD_CONST, .operand.int_value = 0};
+    RavaInstruction_t label0 = {.opcode = RAVA_OP_LABEL, .operand.label_id = 0};
+    RavaInstruction_t instr1 = {.opcode = RAVA_OP_LOAD_CONST, .operand.int_value = 1};
+    RavaInstruction_t label1 = {.opcode = RAVA_OP_LABEL, .operand.label_id = 1};
+    RavaInstruction_t instr2 = {.opcode = RAVA_OP_LOAD_CONST, .operand.int_value = 2};
+    RavaInstruction_t label2 = {.opcode = RAVA_OP_LABEL, .operand.label_id = 2};
+
+    rava_instruction_list_add(list, instr0);
+    rava_instruction_list_add(list, label0);
+    rava_instruction_list_add(list, instr1);
+    rava_instruction_list_add(list, label1);
+    rava_instruction_list_add(list, instr2);
+    rava_instruction_list_add(list, label2);
+
+    LabelTable_t* table = rava_labeltable_create(list);
+    assert(table != NULL);
+
+    assert(rava_labeltable_lookup(table, 0) == 2);
+    assert(rava_labeltable_lookup(table, 1) == 4);
+    assert(rava_labeltable_lookup(table, 2) == 6);
+
+    rava_labeltable_destroy(table);
+    rava_instruction_list_destroy(list);
+}
+
+TEST(missing_label) {
+    RavaInstructionList_t* list = rava_instruction_list_create();
+
+    RavaInstruction_t label = {.opcode = RAVA_OP_LABEL, .operand.label_id = 5};
+    rava_instruction_list_add(list, label);
+
+    LabelTable_t* table = rava_labeltable_create(list);
+    assert(table != NULL);
+
+    assert(rava_labeltable_lookup(table, 0) == 0);
+    assert(rava_labeltable_lookup(table, 1) == 0);
+    assert(rava_labeltable_lookup(table, 5) == 1);
+
+    rava_labeltable_destroy(table);
+    rava_instruction_list_destroy(list);
+}
+
+TEST(out_of_range) {
+    RavaInstructionList_t* list = rava_instruction_list_create();
+
+    RavaInstruction_t label = {.opcode = RAVA_OP_LABEL, .operand.label_id = 2};
+    rava_instruction_list_add(list, label);
+
+    LabelTable_t* table = rava_labeltable_create(list);
+    assert(table != NULL);
+
+    assert(rava_labeltable_lookup(table, 100) == 0);
+    assert(rava_labeltable_lookup(table, -1) == 0);
+
+    rava_labeltable_destroy(table);
+    rava_instruction_list_destroy(list);
+}
+
+int main(void) {
+    printf("=== Label Table Unit Tests ===\n\n");
+
+    RUN_TEST(create_empty);
+    RUN_TEST(create_null);
+    RUN_TEST(single_label);
+    RUN_TEST(multiple_labels);
+    RUN_TEST(missing_label);
+    RUN_TEST(out_of_range);
+
+    printf("\n=== Results: %d tests passed ===\n", tests_passed);
+    return 0;
+}
diff --git a/tests/test_lexer.c b/tests/test_lexer.c
new file mode 100644
index 0000000..7c0f9c5
--- /dev/null
+++ b/tests/test_lexer.c
@@ -0,0 +1,95 @@
+#include "../lexer/lexer.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+static const char* token_type_to_string(RavaTokenType_e type) {
+    switch (type) {
+        case RAVA_TOKEN_EOF: return "EOF";
+        case RAVA_TOKEN_KEYWORD_CLASS: return "KEYWORD_CLASS";
+        case RAVA_TOKEN_KEYWORD_PUBLIC: return "KEYWORD_PUBLIC";
+        case RAVA_TOKEN_KEYWORD_STATIC: return "KEYWORD_STATIC";
+        case RAVA_TOKEN_KEYWORD_VOID: return "KEYWORD_VOID";
+        case RAVA_TOKEN_KEYWORD_INT: return "KEYWORD_INT";
+        case RAVA_TOKEN_KEYWORD_RETURN: return "KEYWORD_RETURN";
+        case RAVA_TOKEN_KEYWORD_IF: return "KEYWORD_IF";
+        case RAVA_TOKEN_KEYWORD_ELSE: return "KEYWORD_ELSE";
+        case RAVA_TOKEN_IDENTIFIER: return "IDENTIFIER";
+        case RAVA_TOKEN_LITERAL_INTEGER: return "LITERAL_INTEGER";
+        case RAVA_TOKEN_LITERAL_STRING: return "LITERAL_STRING";
+        case RAVA_TOKEN_LITERAL_TRUE: return "LITERAL_TRUE";
+        case RAVA_TOKEN_LITERAL_FALSE: return "LITERAL_FALSE";
+        case RAVA_TOKEN_LITERAL_NULL: return "LITERAL_NULL";
+        case RAVA_TOKEN_LPAREN: return "LPAREN";
+        case RAVA_TOKEN_RPAREN: return "RPAREN";
+        case RAVA_TOKEN_LBRACE: return "LBRACE";
+        case RAVA_TOKEN_RBRACE: return "RBRACE";
+        case RAVA_TOKEN_SEMICOLON: return "SEMICOLON";
+        case RAVA_TOKEN_COMMA: return "COMMA";
+        case RAVA_TOKEN_DOT: return "DOT";
+        case RAVA_TOKEN_ASSIGN: return "ASSIGN";
+        case RAVA_TOKEN_PLUS: return "PLUS";
+        case RAVA_TOKEN_MINUS: return "MINUS";
+        case RAVA_TOKEN_STAR: return "STAR";
+        case RAVA_TOKEN_EQUAL: return "EQUAL";
+        case RAVA_TOKEN_LT: return "LT";
+        case RAVA_TOKEN_GT: return "GT";
+        case RAVA_TOKEN_ERROR: return "ERROR";
+        default: return "UNKNOWN";
+    }
+}
+
+int main() {
+    const char *source =
+        "public class HelloWorld {\n"
+        "    public static void main(String[] args) {\n"
+        "        int x = 42;\n"
+        "        if (x > 0) {\n"
+        "            System.out.println(\"Hello, World!\");\n"
+        "        }\n"
+        "        return;\n"
+        "    }\n"
+        "}\n";
+
+    printf("Source code:\n%s\n", source);
+    printf("\nTokens:\n");
+    printf("%-20s %-30s %s\n", "Type", "Lexeme", "Location");
+    printf("--------------------------------------------------------------------------------\n");
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaToken_t *token;
+
+    do {
+        token = rava_lexer_next_token(lexer);
+        if (token->type == RAVA_TOKEN_ERROR) {
+            printf("ERROR: %s at line %d, column %d\n",
+                   lexer->error_message ? lexer->error_message : "Unknown error",
+                   token->line, token->column);
+            rava_token_destroy(token);
+            break;
+        }
+
+        printf("%-20s %-30s Line %d, Col %d\n",
+               token_type_to_string(token->type),
+               token->lexeme,
+               token->line,
+               token->column);
+
+        if (token->type == RAVA_TOKEN_LITERAL_INTEGER) {
+            printf("    Value: %lld\n", (long long)token->value.int_value);
+        } else if (token->type == RAVA_TOKEN_LITERAL_STRING) {
+            printf("    String Value: \"%s\"\n", token->value.string_value);
+        }
+
+        RavaTokenType_e type = token->type;
+        rava_token_destroy(token);
+
+        if (type == RAVA_TOKEN_EOF) {
+            break;
+        }
+    } while (1);
+
+    rava_lexer_destroy(lexer);
+
+    printf("\nLexer test completed successfully!\n");
+    return 0;
+}
diff --git a/tests/test_lexer.o b/tests/test_lexer.o
new file mode 100644
index 0000000..67139d5
Binary files /dev/null and b/tests/test_lexer.o differ
diff --git a/tests/test_math.c b/tests/test_math.c
new file mode 100644
index 0000000..4e6d54f
--- /dev/null
+++ b/tests/test_math.c
@@ -0,0 +1,166 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test_int(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error: %s\n", name, parser->error_message ? parser->error_message : "unknown");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error: %s\n", name, vm->error_message ? vm->error_message : "unknown");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== Math Class Tests ===\n\n");
+
+    run_test_int("Math.abs positive",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return Math.abs(42);\n"
+        "    }\n"
+        "}\n", 42);
+
+    run_test_int("Math.abs negative",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return Math.abs(-42);\n"
+        "    }\n"
+        "}\n", 42);
+
+    run_test_int("Math.min",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return Math.min(10, 5);\n"
+        "    }\n"
+        "}\n", 5);
+
+    run_test_int("Math.max",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return Math.max(10, 5);\n"
+        "    }\n"
+        "}\n", 10);
+
+    run_test_int("(int)Math.pow 2^8",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int result = (int)Math.pow(2, 8);\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 256);
+
+    run_test_int("(int)Math.sqrt 25",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int result = (int)Math.sqrt(25);\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 5);
+
+    run_test_int("(int)Math.floor 4.9",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int result = (int)Math.floor(4.9);\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 4);
+
+    run_test_int("(int)Math.ceil 4.1",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int result = (int)Math.ceil(4.1);\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 5);
+
+    run_test_int("(int)Math.round 4.7",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int result = (int)Math.round(4.7);\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 5);
+
+    run_test_int("(int)Math.round 4.2",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int result = (int)Math.round(4.2);\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 4);
+
+    run_test_int("(int) double cast",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int result = (int)3.14159;\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 3);
+
+    run_test_int("(int) negative double",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int result = (int)(-7.8);\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", -7);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_math.o b/tests/test_math.o
new file mode 100644
index 0000000..4bbbb3f
Binary files /dev/null and b/tests/test_math.o differ
diff --git a/tests/test_methodcache.c b/tests/test_methodcache.c
new file mode 100644
index 0000000..53d81ca
--- /dev/null
+++ b/tests/test_methodcache.c
@@ -0,0 +1,119 @@
+#include <stdio.h>
+#include <assert.h>
+#include "../runtime/methodcache.h"
+
+static int tests_passed = 0;
+
+#define TEST(name) static void test_##name(void)
+#define RUN_TEST(name) do { \
+    printf("Running %s... ", #name); \
+    test_##name(); \
+    printf("PASSED\n"); \
+    tests_passed++; \
+} while(0)
+
+TEST(create_destroy) {
+    MethodCache_t* cache = rava_methodcache_create();
+    assert(cache != NULL);
+    rava_methodcache_destroy(cache);
+}
+
+TEST(insert_lookup) {
+    MethodCache_t* cache = rava_methodcache_create();
+    assert(cache != NULL);
+
+    int dummy_method = 42;
+    RavaMethod_t* method = (RavaMethod_t*)&dummy_method;
+
+    rava_methodcache_insert(cache, "TestClass", "testMethod", method);
+
+    RavaMethod_t* found = rava_methodcache_lookup(cache, "TestClass", "testMethod");
+    assert(found == method);
+
+    rava_methodcache_destroy(cache);
+}
+
+TEST(lookup_miss) {
+    MethodCache_t* cache = rava_methodcache_create();
+    assert(cache != NULL);
+
+    RavaMethod_t* found = rava_methodcache_lookup(cache, "NonExistent", "method");
+    assert(found == NULL);
+
+    rava_methodcache_destroy(cache);
+}
+
+TEST(multiple_methods) {
+    MethodCache_t* cache = rava_methodcache_create();
+    assert(cache != NULL);
+
+    int m1 = 1, m2 = 2;
+    RavaMethod_t* method1 = (RavaMethod_t*)&m1;
+    RavaMethod_t* method2 = (RavaMethod_t*)&m2;
+
+    rava_methodcache_insert(cache, "TestClass", "methodA", method1);
+    RavaMethod_t* found1 = rava_methodcache_lookup(cache, "TestClass", "methodA");
+    assert(found1 == method1);
+
+    rava_methodcache_insert(cache, "OtherClass", "methodB", method2);
+    RavaMethod_t* found2 = rava_methodcache_lookup(cache, "OtherClass", "methodB");
+    assert(found2 == method2);
+
+    rava_methodcache_destroy(cache);
+}
+
+TEST(clear) {
+    MethodCache_t* cache = rava_methodcache_create();
+    assert(cache != NULL);
+
+    int dummy = 42;
+    RavaMethod_t* method = (RavaMethod_t*)&dummy;
+
+    rava_methodcache_insert(cache, "TestClass", "testMethod", method);
+    assert(rava_methodcache_lookup(cache, "TestClass", "testMethod") == method);
+
+    rava_methodcache_clear(cache);
+    assert(rava_methodcache_lookup(cache, "TestClass", "testMethod") == NULL);
+
+    rava_methodcache_destroy(cache);
+}
+
+TEST(null_params) {
+    MethodCache_t* cache = rava_methodcache_create();
+
+    rava_methodcache_insert(NULL, "Class", "method", NULL);
+    rava_methodcache_insert(cache, NULL, "method", NULL);
+    rava_methodcache_insert(cache, "Class", NULL, NULL);
+
+    assert(rava_methodcache_lookup(NULL, "Class", "method") == NULL);
+    assert(rava_methodcache_lookup(cache, NULL, "method") == NULL);
+    assert(rava_methodcache_lookup(cache, "Class", NULL) == NULL);
+
+    rava_methodcache_destroy(cache);
+}
+
+TEST(hash_function) {
+    uint32_t h1 = rava_methodcache_hash("hello");
+    uint32_t h2 = rava_methodcache_hash("hello");
+    uint32_t h3 = rava_methodcache_hash("world");
+
+    assert(h1 == h2);
+    assert(h1 != h3);
+    assert(h1 != 0);
+    assert(h3 != 0);
+}
+
+int main(void) {
+    printf("=== Method Cache Unit Tests ===\n\n");
+
+    RUN_TEST(create_destroy);
+    RUN_TEST(insert_lookup);
+    RUN_TEST(lookup_miss);
+    RUN_TEST(multiple_methods);
+    RUN_TEST(clear);
+    RUN_TEST(null_params);
+    RUN_TEST(hash_function);
+
+    printf("\n=== Results: %d tests passed ===\n", tests_passed);
+    return 0;
+}
diff --git a/tests/test_multidim_arrays.c b/tests/test_multidim_arrays.c
new file mode 100644
index 0000000..9978650
--- /dev/null
+++ b/tests/test_multidim_arrays.c
@@ -0,0 +1,149 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test_int(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error: %s\n", name, parser->error_message ? parser->error_message : "unknown");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error: %s\n", name, vm->error_message ? vm->error_message : "unknown");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== Multi-dimensional Array Tests ===\n\n");
+
+    run_test_int("2d array outer length",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[][] a = new int[4][5];\n"
+        "        return a.length;\n"
+        "    }\n"
+        "}\n", 4);
+
+    run_test_int("2d array inner length",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[][] a = new int[4][5];\n"
+        "        return a[0].length;\n"
+        "    }\n"
+        "}\n", 5);
+
+    run_test_int("2d array basic store and load",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[][] a = new int[2][3];\n"
+        "        a[0][1] = 15;\n"
+        "        return a[0][1];\n"
+        "    }\n"
+        "}\n", 15);
+
+    run_test_int("2d array multiple cells",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[][] a = new int[2][3];\n"
+        "        a[0][0] = 1;\n"
+        "        a[0][1] = 2;\n"
+        "        a[1][0] = 3;\n"
+        "        a[1][1] = 4;\n"
+        "        return a[0][0] + a[0][1] + a[1][0] + a[1][1];\n"
+        "    }\n"
+        "}\n", 10);
+
+    run_test_int("2d array row iteration",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[][] a = new int[3][2];\n"
+        "        a[0][0] = 1; a[0][1] = 2;\n"
+        "        a[1][0] = 3; a[1][1] = 4;\n"
+        "        a[2][0] = 5; a[2][1] = 6;\n"
+        "        int sum = 0;\n"
+        "        for (int i = 0; i < a.length; i++) {\n"
+        "            sum = sum + a[i][0] + a[i][1];\n"
+        "        }\n"
+        "        return sum;\n"
+        "    }\n"
+        "}\n", 21);
+
+    run_test_int("2d array nested loop",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[][] a = new int[2][3];\n"
+        "        int v = 1;\n"
+        "        for (int i = 0; i < 2; i++) {\n"
+        "            for (int j = 0; j < 3; j++) {\n"
+        "                a[i][j] = v;\n"
+        "                v = v + 1;\n"
+        "            }\n"
+        "        }\n"
+        "        return a[0][0] + a[0][2] + a[1][1];\n"
+        "    }\n"
+        "}\n", 9);
+
+    run_test_int("2d array different inner lengths",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int[][] a = new int[3][4];\n"
+        "        int[][] b = new int[2][6];\n"
+        "        return a[0].length + b[0].length;\n"
+        "    }\n"
+        "}\n", 10);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_multidim_arrays.o b/tests/test_multidim_arrays.o
new file mode 100644
index 0000000..095fcec
Binary files /dev/null and b/tests/test_multidim_arrays.o differ
diff --git a/tests/test_nanbox.c b/tests/test_nanbox.c
new file mode 100644
index 0000000..2897b4f
--- /dev/null
+++ b/tests/test_nanbox.c
@@ -0,0 +1,146 @@
+#include <stdio.h>
+#include <assert.h>
+#include <math.h>
+#include "../runtime/nanbox.h"
+
+static int tests_passed = 0;
+static int tests_failed = 0;
+
+#define TEST(name) static void test_##name(void)
+#define RUN_TEST(name) do { \
+    printf("Running %s... ", #name); \
+    test_##name(); \
+    printf("PASSED\n"); \
+    tests_passed++; \
+} while(0)
+
+TEST(int_basic) {
+    RavaNanboxValue_t val = rava_nanbox_int(42);
+    assert(rava_nanbox_is_int(val));
+    assert(!rava_nanbox_is_bool(val));
+    assert(!rava_nanbox_is_null(val));
+    assert(rava_nanbox_as_int(val) == 42);
+}
+
+TEST(int_negative) {
+    RavaNanboxValue_t val = rava_nanbox_int(-100);
+    assert(rava_nanbox_is_int(val));
+    assert(rava_nanbox_as_int(val) == -100);
+}
+
+TEST(int_zero) {
+    RavaNanboxValue_t val = rava_nanbox_int(0);
+    assert(rava_nanbox_is_int(val));
+    assert(rava_nanbox_as_int(val) == 0);
+}
+
+TEST(long_basic) {
+    RavaNanboxValue_t val = rava_nanbox_long(1000000000000LL);
+    assert(rava_nanbox_is_long(val));
+    int64_t result = rava_nanbox_as_long(val);
+    (void)result;
+}
+
+TEST(bool_true) {
+    RavaNanboxValue_t val = rava_nanbox_bool(true);
+    assert(rava_nanbox_is_bool(val));
+    assert(rava_nanbox_as_bool(val) == true);
+}
+
+TEST(bool_false) {
+    RavaNanboxValue_t val = rava_nanbox_bool(false);
+    assert(rava_nanbox_is_bool(val));
+    assert(rava_nanbox_as_bool(val) == false);
+}
+
+TEST(null) {
+    RavaNanboxValue_t val = rava_nanbox_null();
+    assert(rava_nanbox_is_null(val));
+    assert(!rava_nanbox_is_int(val));
+    assert(!rava_nanbox_is_bool(val));
+}
+
+TEST(double_basic) {
+    RavaNanboxValue_t val = rava_nanbox_double(3.14159);
+    assert(rava_nanbox_is_double(val));
+    double d = rava_nanbox_as_double(val);
+    assert(fabs(d - 3.14159) < 0.0001);
+}
+
+TEST(double_negative) {
+    RavaNanboxValue_t val = rava_nanbox_double(-123.456);
+    assert(rava_nanbox_is_double(val));
+    double d = rava_nanbox_as_double(val);
+    assert(fabs(d - (-123.456)) < 0.0001);
+}
+
+TEST(conversion_int_to_long) {
+    RavaNanboxValue_t val = rava_nanbox_int(42);
+    assert(rava_nanbox_to_long(val) == 42);
+}
+
+TEST(conversion_int_to_double) {
+    RavaNanboxValue_t val = rava_nanbox_int(10);
+    assert(fabs(rava_nanbox_to_double(val) - 10.0) < 0.0001);
+}
+
+TEST(conversion_bool_to_int) {
+    RavaNanboxValue_t t = rava_nanbox_bool(true);
+    RavaNanboxValue_t f = rava_nanbox_bool(false);
+    assert(rava_nanbox_to_int(t) == 1);
+    assert(rava_nanbox_to_int(f) == 0);
+}
+
+TEST(to_bool) {
+    assert(rava_nanbox_to_bool(rava_nanbox_null()) == false);
+    assert(rava_nanbox_to_bool(rava_nanbox_bool(true)) == true);
+    assert(rava_nanbox_to_bool(rava_nanbox_bool(false)) == false);
+    assert(rava_nanbox_to_bool(rava_nanbox_int(0)) == false);
+    assert(rava_nanbox_to_bool(rava_nanbox_int(1)) == true);
+    assert(rava_nanbox_to_bool(rava_nanbox_int(-1)) == true);
+}
+
+TEST(object_pointer) {
+    int dummy = 42;
+    RavaNanboxValue_t val = rava_nanbox_object(&dummy);
+    assert(rava_nanbox_is_object(val));
+    assert(rava_nanbox_as_object(val) == &dummy);
+}
+
+TEST(string_pointer) {
+    const char* str = "hello";
+    RavaNanboxValue_t val = rava_nanbox_string(str);
+    assert(rava_nanbox_is_string(val));
+    assert(rava_nanbox_as_string(val) == str);
+}
+
+TEST(array_pointer) {
+    int arr[10];
+    RavaNanboxValue_t val = rava_nanbox_array(arr);
+    assert(rava_nanbox_is_array(val));
+    assert(rava_nanbox_as_array(val) == arr);
+}
+
+int main(void) {
+    printf("=== NaN Boxing Unit Tests ===\n\n");
+
+    RUN_TEST(int_basic);
+    RUN_TEST(int_negative);
+    RUN_TEST(int_zero);
+    RUN_TEST(long_basic);
+    RUN_TEST(bool_true);
+    RUN_TEST(bool_false);
+    RUN_TEST(null);
+    RUN_TEST(double_basic);
+    RUN_TEST(double_negative);
+    RUN_TEST(conversion_int_to_long);
+    RUN_TEST(conversion_int_to_double);
+    RUN_TEST(conversion_bool_to_int);
+    RUN_TEST(to_bool);
+    RUN_TEST(object_pointer);
+    RUN_TEST(string_pointer);
+    RUN_TEST(array_pointer);
+
+    printf("\n=== Results: %d passed, %d failed ===\n", tests_passed, tests_failed);
+    return tests_failed > 0 ? 1 : 0;
+}
diff --git a/tests/test_negative.c b/tests/test_negative.c
new file mode 100644
index 0000000..45947e9
--- /dev/null
+++ b/tests/test_negative.c
@@ -0,0 +1,234 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef enum {
+    EXPECT_PARSE_ERROR,
+    EXPECT_SEMANTIC_ERROR,
+    EXPECT_RUNTIME_ERROR,
+    EXPECT_MISSING_CLASS,
+    EXPECT_MISSING_METHOD
+} ExpectedError_e;
+
+static bool test_error(const char *name, const char *source, ExpectedError_e expected,
+                       const char *exec_class, const char *exec_method) {
+    printf("Test: %-40s ... ", name);
+    fflush(stdout);
+
+    if (!source || strlen(source) == 0) {
+        printf("PASS (skipped empty input)\n");
+        return true;
+    }
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    if (!lexer) {
+        bool success = (expected == EXPECT_PARSE_ERROR);
+        printf("%s\n", success ? "PASS" : "FAIL");
+        return success;
+    }
+
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        bool success = (expected == EXPECT_PARSE_ERROR);
+        printf("%s\n", success ? "PASS" : "FAIL");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return success;
+    }
+
+    if (expected == EXPECT_PARSE_ERROR) {
+        printf("FAIL (expected parse error)\n");
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return false;
+    }
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        bool success = (expected == EXPECT_SEMANTIC_ERROR);
+        printf("%s\n", success ? "PASS" : "FAIL");
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return success;
+    }
+
+    if (expected == EXPECT_SEMANTIC_ERROR) {
+        printf("FAIL (expected semantic error)\n");
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return false;
+    }
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        bool success = (expected == EXPECT_RUNTIME_ERROR);
+        printf("%s\n", success ? "PASS" : "FAIL");
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return success;
+    }
+
+    RavaVM_t *vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, exec_class, exec_method)) {
+        bool success = (expected == EXPECT_RUNTIME_ERROR ||
+                       expected == EXPECT_MISSING_CLASS ||
+                       expected == EXPECT_MISSING_METHOD);
+        printf("%s\n", success ? "PASS" : "FAIL");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return success;
+    }
+
+    printf("FAIL (expected error)\n");
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+    return false;
+}
+
+int main(void) {
+    printf("=== NEGATIVE TEST CASES ===\n\n");
+
+    int passed = 0;
+    int total = 0;
+
+    total++;
+    if (test_error("Missing class body",
+        "public class Test",
+        EXPECT_PARSE_ERROR, "Test", "main")) {
+        passed++;
+    }
+
+    total++;
+    if (test_error("Missing method body",
+        "public class Test {\n"
+        "    public static int main()\n"
+        "}\n",
+        EXPECT_PARSE_ERROR, "Test", "main")) {
+        passed++;
+    }
+
+    total++;
+    if (test_error("Unclosed brace",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return 0;\n"
+        "}\n",
+        EXPECT_PARSE_ERROR, "Test", "main")) {
+        passed++;
+    }
+
+    total++;
+    if (test_error("Missing semicolon",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 5\n"
+        "        return x;\n"
+        "    }\n"
+        "}\n",
+        EXPECT_PARSE_ERROR, "Test", "main")) {
+        passed++;
+    }
+
+    total++;
+    if (test_error("Undefined variable",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return undefinedVar;\n"
+        "    }\n"
+        "}\n",
+        EXPECT_SEMANTIC_ERROR, "Test", "main")) {
+        passed++;
+    }
+
+    total++;
+    if (test_error("Undefined method call",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return undefinedMethod();\n"
+        "    }\n"
+        "}\n",
+        EXPECT_SEMANTIC_ERROR, "Test", "main")) {
+        passed++;
+    }
+
+    total++;
+    if (test_error("Missing class at runtime",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n",
+        EXPECT_MISSING_CLASS, "NonExistent", "main")) {
+        passed++;
+    }
+
+    total++;
+    if (test_error("Missing method at runtime",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n",
+        EXPECT_MISSING_METHOD, "Test", "nonExistent")) {
+        passed++;
+    }
+
+    total++;
+    if (test_error("Duplicate variable",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 5;\n"
+        "        int x = 10;\n"
+        "        return x;\n"
+        "    }\n"
+        "}\n",
+        EXPECT_SEMANTIC_ERROR, "Test", "main")) {
+        passed++;
+    }
+
+    total++;
+    if (test_error("Malformed for loop",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        for (int i = 0; i < 10) {\n"
+        "        }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n",
+        EXPECT_PARSE_ERROR, "Test", "main")) {
+        passed++;
+    }
+
+    printf("\n=== Results: %d/%d tests passed ===\n", passed, total);
+
+    return (passed == total) ? 0 : 1;
+}
diff --git a/tests/test_negative.o b/tests/test_negative.o
new file mode 100644
index 0000000..30a237c
Binary files /dev/null and b/tests/test_negative.o differ
diff --git a/tests/test_objects.c b/tests/test_objects.c
new file mode 100644
index 0000000..11fbdcf
--- /dev/null
+++ b/tests/test_objects.c
@@ -0,0 +1,77 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static char* read_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (!file) return NULL;
+    fseek(file, 0, SEEK_END);
+    long size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    char *content = malloc(size + 1);
+    size_t read_bytes = fread(content, 1, size, file); (void)read_bytes;
+    content[size] = '\0';
+    fclose(file);
+    return content;
+}
+
+int main() {
+    char *source = read_file("examples/13_SimpleObject.java");
+    if (!source) {
+        printf("Failed to read file\n");
+        return 1;
+    }
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Parse: OK\n");
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        printf("Semantic error: %s\n", analyzer->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Semantic: OK\n");
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        printf("IR generation failed\n");
+        free(source);
+        return 1;
+    }
+
+    printf("IR Gen: OK\n");
+    printf("\nOutput:\n");
+
+    RavaVM_t *vm = rava_vm_create(program);
+    if (!rava_vm_execute(vm, "SimpleObject", "main")) {
+        printf("Runtime error: %s\n", vm->error_message);
+        rava_vm_destroy(vm);
+        free(source);
+        return 1;
+    }
+
+    printf("\nExecution: OK\n");
+
+    rava_vm_destroy(vm);
+    free(source);
+    return 0;
+}
diff --git a/tests/test_objects.o b/tests/test_objects.o
new file mode 100644
index 0000000..cc8677f
Binary files /dev/null and b/tests/test_objects.o differ
diff --git a/tests/test_opcode_count.c b/tests/test_opcode_count.c
new file mode 100644
index 0000000..549a434
--- /dev/null
+++ b/tests/test_opcode_count.c
@@ -0,0 +1,17 @@
+#include <stdio.h>
+#include "../ir/ir.h"
+
+int main(void) {
+    printf("RAVA_OP_NOP = %d\n", RAVA_OP_NOP);
+    printf("RAVA_OP_LOAD_CONST = %d\n", RAVA_OP_LOAD_CONST);
+    printf("RAVA_OP_CALL = %d\n", RAVA_OP_CALL);
+    printf("RAVA_OP_CALL_STATIC = %d\n", RAVA_OP_CALL_STATIC);
+    printf("RAVA_OP_CALL_RECURSIVE = %d\n", RAVA_OP_CALL_RECURSIVE);
+    printf("RAVA_OP_CALL_VIRTUAL = %d\n", RAVA_OP_CALL_VIRTUAL);
+    printf("RAVA_OP_CALL_SUPER = %d\n", RAVA_OP_CALL_SUPER);
+    printf("RAVA_OP_CALL_NATIVE = %d\n", RAVA_OP_CALL_NATIVE);
+    printf("RAVA_OP_RETURN = %d\n", RAVA_OP_RETURN);
+    printf("RAVA_OP_MATH_RANDOM = %d\n", RAVA_OP_MATH_RANDOM);
+    printf("Total opcodes: %d\n", RAVA_OP_MATH_RANDOM + 1);
+    return 0;
+}
diff --git a/tests/test_parser.c b/tests/test_parser.c
new file mode 100644
index 0000000..db97901
--- /dev/null
+++ b/tests/test_parser.c
@@ -0,0 +1,50 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+extern void rava_ast_print(RavaASTNode_t *node, int depth);
+
+int main() {
+    const char *source =
+        "public class Calculator {\n"
+        "    public static int add(int a, int b) {\n"
+        "        int result = a + b;\n"
+        "        return result;\n"
+        "    }\n"
+        "\n"
+        "    public static void main(String[] args) {\n"
+        "        int x = 10;\n"
+        "        int y = 20;\n"
+        "        int sum = add(x, y);\n"
+        "        if (sum > 0) {\n"
+        "            System.out.println(\"Positive result\");\n"
+        "        }\n"
+        "    }\n"
+        "}\n";
+
+    printf("Source code:\n%s\n", source);
+    printf("\nAbstract Syntax Tree:\n");
+    printf("================================================================================\n\n");
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message ? parser->error_message : "Unknown error");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return 1;
+    }
+
+    rava_ast_print(ast, 0);
+
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+
+    printf("\nParser test completed successfully!\n");
+    return 0;
+}
diff --git a/tests/test_parser.o b/tests/test_parser.o
new file mode 100644
index 0000000..f4e5f47
Binary files /dev/null and b/tests/test_parser.o differ
diff --git a/tests/test_pascal_only.c b/tests/test_pascal_only.c
new file mode 100644
index 0000000..875b873
--- /dev/null
+++ b/tests/test_pascal_only.c
@@ -0,0 +1,91 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static char* read_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (!file) return NULL;
+    fseek(file, 0, SEEK_END);
+    long size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    char *content = malloc(size + 1);
+    size_t read_bytes = fread(content, 1, size, file); (void)read_bytes;
+    content[size] = '\0';
+    fclose(file);
+    return content;
+}
+
+int main() {
+    char *source = read_file("examples/08_PascalTriangle.java");
+    if (!source) return 1;
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+    if (parser->had_error) {
+        free(source);
+        return 1;
+    }
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        free(source);
+        return 1;
+    }
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+    if (!program) {
+        free(source);
+        return 1;
+    }
+
+    RavaVM_t *vm = rava_vm_create(program);
+    if (!rava_vm_execute(vm, "PascalTriangle", "main")) {
+        printf("Runtime error\n");
+        rava_vm_destroy(vm);
+        free(source);
+        return 1;
+    }
+
+    printf("\nCleaning up VM...\n");
+    fflush(stdout);
+    rava_vm_destroy(vm);
+    
+    printf("Cleaning up program...\n");
+    fflush(stdout);
+    rava_program_destroy(program);
+    
+    printf("Cleaning up IR generator...\n");
+    fflush(stdout);
+    rava_ir_generator_destroy(ir_gen);
+    
+    printf("Cleaning up analyzer...\n");
+    fflush(stdout);
+    rava_semantic_analyzer_destroy(analyzer);
+    
+    printf("Cleaning up AST...\n");
+    fflush(stdout);
+    rava_ast_node_destroy(ast);
+    
+    printf("Cleaning up parser...\n");
+    fflush(stdout);
+    rava_parser_destroy(parser);
+    
+    printf("Cleaning up lexer...\n");
+    fflush(stdout);
+    rava_lexer_destroy(lexer);
+    
+    printf("Freeing source...\n");
+    fflush(stdout);
+    free(source);
+    
+    printf("Done!\n");
+    return 0;
+}
diff --git a/tests/test_println.c b/tests/test_println.c
new file mode 100644
index 0000000..08dc115
--- /dev/null
+++ b/tests/test_println.c
@@ -0,0 +1,72 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+int main() {
+    const char *source =
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        System.out.println(42);\n"
+        "        System.out.println(100);\n"
+        "        int x = 10;\n"
+        "        int y = 20;\n"
+        "        System.out.println(x + y);\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n";
+
+    printf("Source:\n%s\n", source);
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message);
+        return 1;
+    }
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        printf("Semantic error: %s\n", analyzer->error_message);
+        return 1;
+    }
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        printf("IR generation failed\n");
+        return 1;
+    }
+
+    printf("\nGenerated IR:\n");
+    rava_ir_print(program);
+
+    RavaVM_t *vm = rava_vm_create(program);
+    printf("\nExecuting Test.main()...\n");
+    printf("Output:\n");
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("Runtime error: %s\n", vm->error_message);
+        rava_vm_destroy(vm);
+        return 1;
+    }
+
+    printf("\n✅ Execution completed successfully!\n");
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+
+    return 0;
+}
diff --git a/tests/test_runtime.c b/tests/test_runtime.c
new file mode 100644
index 0000000..22be1e2
--- /dev/null
+++ b/tests/test_runtime.c
@@ -0,0 +1,172 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+static bool run_test(const char *name, const char *source, const char *class_name,
+                     const char *method_name, int expected_result) {
+    printf("\n========================================\n");
+    printf("Test: %s\n", name);
+    printf("========================================\n");
+    printf("Source:\n%s\n", source);
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("❌ Parse error: %s\n", parser->error_message);
+        return false;
+    }
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        printf("❌ Semantic error: %s\n", analyzer->error_message);
+        return false;
+    }
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        printf("❌ IR generation failed\n");
+        return false;
+    }
+
+    printf("\nGenerated IR:\n");
+    rava_ir_print(program);
+
+    RavaVM_t *vm = rava_vm_create(program);
+    printf("\nExecuting %s.%s()...\n", class_name, method_name);
+
+    if (!rava_vm_execute(vm, class_name, method_name)) {
+        printf("❌ Runtime error: %s\n", vm->error_message);
+        rava_vm_destroy(vm);
+        return false;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    printf("Result: %d\n", result_int);
+
+    bool success = (result_int == expected_result);
+    if (success) {
+        printf("✅ PASS (expected %d, got %d)\n", expected_result, result_int);
+    } else {
+        printf("❌ FAIL (expected %d, got %d)\n", expected_result, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+
+    return success;
+}
+
+int main() {
+    printf("================================================================================\n");
+    printf("RAVA JAVA INTERPRETER - END-TO-END RUNTIME TESTS\n");
+    printf("================================================================================\n");
+
+    int passed = 0;
+    int total = 0;
+
+    total++;
+    if (run_test("Simple Addition",
+        "public class Test {\n"
+        "    public static int add() {\n"
+        "        int a = 10;\n"
+        "        int b = 20;\n"
+        "        int result = a + b;\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n",
+        "Test", "add", 30)) {
+        passed++;
+    }
+
+    total++;
+    if (run_test("Multiple Operations",
+        "public class Test {\n"
+        "    public static int compute() {\n"
+        "        int a = 5;\n"
+        "        int b = 3;\n"
+        "        int sum = a + b;\n"
+        "        int product = a * b;\n"
+        "        int result = sum + product;\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n",
+        "Test", "compute", 23)) {
+        passed++;
+    }
+
+    total++;
+    if (run_test("Conditional (True Branch)",
+        "public class Test {\n"
+        "    public static int conditional() {\n"
+        "        int x = 10;\n"
+        "        int result = 0;\n"
+        "        if (x > 5) {\n"
+        "            result = 100;\n"
+        "        }\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n",
+        "Test", "conditional", 100)) {
+        passed++;
+    }
+
+    total++;
+    if (run_test("Conditional (False Branch)",
+        "public class Test {\n"
+        "    public static int conditional() {\n"
+        "        int x = 3;\n"
+        "        int result = 0;\n"
+        "        if (x > 5) {\n"
+        "            result = 100;\n"
+        "        }\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n",
+        "Test", "conditional", 0)) {
+        passed++;
+    }
+
+    total++;
+    if (run_test("Factorial (Recursive)",
+        "public class Test {\n"
+        "    public static int factorial(int n) {\n"
+        "        if (n <= 1) {\n"
+        "            return 1;\n"
+        "        }\n"
+        "        return n * factorial(n - 1);\n"
+        "    }\n"
+        "}\n",
+        "Test", "factorial", 1)) {
+        passed++;
+    }
+
+    printf("\n================================================================================\n");
+    printf("TEST SUMMARY\n");
+    printf("================================================================================\n");
+    printf("Passed: %d/%d\n", passed, total);
+    printf("Failed: %d/%d\n", total - passed, total);
+
+    if (passed == total) {
+        printf("\n🎉 ALL TESTS PASSED! The Rava interpreter is executing Java code!\n");
+    } else {
+        printf("\n⚠️  Some tests failed.\n");
+    }
+
+    return (passed == total) ? 0 : 1;
+}
diff --git a/tests/test_runtime.o b/tests/test_runtime.o
new file mode 100644
index 0000000..66875fc
Binary files /dev/null and b/tests/test_runtime.o differ
diff --git a/tests/test_semantic.c b/tests/test_semantic.c
new file mode 100644
index 0000000..2bf912a
--- /dev/null
+++ b/tests/test_semantic.c
@@ -0,0 +1,74 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+int main() {
+    const char *source =
+        "public class Test {\n"
+        "    public static int calculate(int x, int y) {\n"
+        "        int sum = x + y;\n"
+        "        int product = x * y;\n"
+        "        boolean isPositive = sum > 0;\n"
+        "        if (isPositive) {\n"
+        "            return sum;\n"
+        "        }\n"
+        "        return product;\n"
+        "    }\n"
+        "\n"
+        "    public static void main(int argc) {\n"
+        "        int result = calculate(10, 20);\n"
+        "        int doubled = result * 2;\n"
+        "    }\n"
+        "}\n";
+
+    printf("Source code:\n%s\n", source);
+    printf("\nSemantic Analysis:\n");
+    printf("================================================================================\n\n");
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message ? parser->error_message : "Unknown error");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return 1;
+    }
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+
+    bool success = rava_semantic_analyze(analyzer, ast);
+
+    if (success) {
+        printf("✓ Semantic analysis passed successfully!\n\n");
+        printf("Symbol table contains:\n");
+        printf("- Class: Test\n");
+        printf("  - Method: calculate (returns int)\n");
+        printf("    - Parameter: x (int)\n");
+        printf("    - Parameter: y (int)\n");
+        printf("    - Variable: sum (int)\n");
+        printf("    - Variable: product (int)\n");
+        printf("    - Variable: isPositive (boolean)\n");
+        printf("  - Method: main (returns void)\n");
+        printf("    - Parameter: argc (int)\n");
+        printf("    - Variable: result (int)\n");
+        printf("    - Variable: doubled (int)\n");
+    } else {
+        printf("✗ Semantic analysis failed!\n");
+        if (analyzer->error_message) {
+            printf("Error: %s\n", analyzer->error_message);
+        }
+        printf("Total errors: %d\n", analyzer->error_count);
+    }
+
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+
+    printf("\nSemantic test completed!\n");
+    return success ? 0 : 1;
+}
diff --git a/tests/test_semantic.o b/tests/test_semantic.o
new file mode 100644
index 0000000..3a02b27
Binary files /dev/null and b/tests/test_semantic.o differ
diff --git a/tests/test_shortcircuit.c b/tests/test_shortcircuit.c
new file mode 100644
index 0000000..8a5feab
--- /dev/null
+++ b/tests/test_shortcircuit.c
@@ -0,0 +1,165 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test_int(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error: %s\n", name, parser->error_message ? parser->error_message : "unknown");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error: %s\n", name, vm->error_message ? vm->error_message : "unknown");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== Short-Circuit Evaluation Tests ===\n\n");
+
+    run_test_int("AND true && true",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        if (true && true) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 1);
+
+    run_test_int("AND true && false",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        if (true && false) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test_int("AND false && true",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        if (false && true) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test_int("OR false || true",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        if (false || true) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 1);
+
+    run_test_int("OR true || false",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        if (true || false) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 1);
+
+    run_test_int("OR false || false",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        if (false || false) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test_int("short-circuit AND skips second",
+        "public class Test {\n"
+        "    public static int x = 0;\n"
+        "    public static boolean incAndReturn() {\n"
+        "        x = x + 1;\n"
+        "        return true;\n"
+        "    }\n"
+        "    public static int main() {\n"
+        "        if (false && incAndReturn()) { }\n"
+        "        return x;\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test_int("short-circuit OR skips second",
+        "public class Test {\n"
+        "    public static int x = 0;\n"
+        "    public static boolean incAndReturn() {\n"
+        "        x = x + 1;\n"
+        "        return false;\n"
+        "    }\n"
+        "    public static int main() {\n"
+        "        if (true || incAndReturn()) { }\n"
+        "        return x;\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test_int("AND with comparison",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 5;\n"
+        "        if (x > 0 && x < 10) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 1);
+
+    run_test_int("OR with comparison",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 15;\n"
+        "        if (x < 0 || x > 10) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 1);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_shortcircuit.o b/tests/test_shortcircuit.o
new file mode 100644
index 0000000..6fb9637
Binary files /dev/null and b/tests/test_shortcircuit.o differ
diff --git a/tests/test_static.c b/tests/test_static.c
new file mode 100644
index 0000000..8276cc8
--- /dev/null
+++ b/tests/test_static.c
@@ -0,0 +1,135 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test_int(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error: %s\n", name, parser->error_message ? parser->error_message : "unknown");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error: %s\n", name, vm->error_message ? vm->error_message : "unknown");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== Static Field Tests ===\n\n");
+
+    run_test_int("static field basic read/write",
+        "class Counter {\n"
+        "    static int count;\n"
+        "}\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        Counter.count = 42;\n"
+        "        return Counter.count;\n"
+        "    }\n"
+        "}\n", 42);
+
+    run_test_int("static field increment",
+        "class Counter {\n"
+        "    static int count;\n"
+        "}\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        Counter.count = 10;\n"
+        "        Counter.count = Counter.count + 5;\n"
+        "        return Counter.count;\n"
+        "    }\n"
+        "}\n", 15);
+
+    run_test_int("static field in same class",
+        "public class Test {\n"
+        "    static int value;\n"
+        "    public static int main() {\n"
+        "        Test.value = 100;\n"
+        "        return Test.value;\n"
+        "    }\n"
+        "}\n", 100);
+
+    run_test_int("multiple static fields",
+        "class Data {\n"
+        "    static int a;\n"
+        "    static int b;\n"
+        "    static int c;\n"
+        "}\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        Data.a = 10;\n"
+        "        Data.b = 20;\n"
+        "        Data.c = 30;\n"
+        "        return Data.a + Data.b + Data.c;\n"
+        "    }\n"
+        "}\n", 60);
+
+    run_test_int("static field across classes",
+        "class ClassA {\n"
+        "    static int val;\n"
+        "}\n"
+        "class ClassB {\n"
+        "    static int val;\n"
+        "}\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        ClassA.val = 100;\n"
+        "        ClassB.val = 200;\n"
+        "        return ClassA.val + ClassB.val;\n"
+        "    }\n"
+        "}\n", 300);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_static.o b/tests/test_static.o
new file mode 100644
index 0000000..cd62a7f
Binary files /dev/null and b/tests/test_static.o differ
diff --git a/tests/test_static_field_parse.c b/tests/test_static_field_parse.c
new file mode 100644
index 0000000..c686e1a
--- /dev/null
+++ b/tests/test_static_field_parse.c
@@ -0,0 +1,40 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+static char* read_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (!file) return NULL;
+    fseek(file, 0, SEEK_END);
+    long size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    char *content = malloc(size + 1);
+    size_t read_bytes = fread(content, 1, size, file); (void)read_bytes;
+    content[size] = '\0';
+    fclose(file);
+    return content;
+}
+
+int main() {
+    char *source = read_file("examples/11_TowerOfHanoiStatic.java");
+    if (!source) {
+        printf("Failed to read file\n");
+        return 1;
+    }
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Parsed successfully!\n");
+
+    free(source);
+    return 0;
+}
diff --git a/tests/test_static_init.c b/tests/test_static_init.c
new file mode 100644
index 0000000..4886403
--- /dev/null
+++ b/tests/test_static_init.c
@@ -0,0 +1,134 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test_int(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error: %s\n", name, parser->error_message ? parser->error_message : "unknown");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error: %s\n", name, vm->error_message ? vm->error_message : "unknown");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== Static Field Initializer Tests ===\n\n");
+
+    run_test_int("static field with literal initializer",
+        "public class Test {\n"
+        "    static int v = 42;\n"
+        "    public static int main() {\n"
+        "        return Test.v;\n"
+        "    }\n"
+        "}\n", 42);
+
+    run_test_int("static field with expression initializer",
+        "public class Test {\n"
+        "    static int v = 10 + 32;\n"
+        "    public static int main() {\n"
+        "        return Test.v;\n"
+        "    }\n"
+        "}\n", 42);
+
+    run_test_int("multiple static fields with initializers",
+        "public class Test {\n"
+        "    static int a = 10;\n"
+        "    static int b = 20;\n"
+        "    static int c = 12;\n"
+        "    public static int main() {\n"
+        "        return Test.a + Test.b + Test.c;\n"
+        "    }\n"
+        "}\n", 42);
+
+    run_test_int("static field initializer can be overwritten",
+        "public class Test {\n"
+        "    static int v = 10;\n"
+        "    public static int main() {\n"
+        "        Test.v = 42;\n"
+        "        return Test.v;\n"
+        "    }\n"
+        "}\n", 42);
+
+    run_test_int("static field used in expression",
+        "public class Test {\n"
+        "    static int base = 40;\n"
+        "    public static int main() {\n"
+        "        return Test.base + 2;\n"
+        "    }\n"
+        "}\n", 42);
+
+    run_test_int("static field in different class",
+        "class Data {\n"
+        "    static int value = 42;\n"
+        "}\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return Data.value;\n"
+        "    }\n"
+        "}\n", 42);
+
+    run_test_int("static field with negative initializer",
+        "public class Test {\n"
+        "    static int v = 100 - 58;\n"
+        "    public static int main() {\n"
+        "        return Test.v;\n"
+        "    }\n"
+        "}\n", 42);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_static_init.o b/tests/test_static_init.o
new file mode 100644
index 0000000..ece6599
Binary files /dev/null and b/tests/test_static_init.o differ
diff --git a/tests/test_string_methods.c b/tests/test_string_methods.c
new file mode 100644
index 0000000..49220fc
--- /dev/null
+++ b/tests/test_string_methods.c
@@ -0,0 +1,253 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test_int(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error: %s\n", name, parser->error_message ? parser->error_message : "unknown");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error: %s\n", name, vm->error_message ? vm->error_message : "unknown");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== String Methods Tests ===\n\n");
+
+    run_test_int("String.length",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String s = \"Hello\";\n"
+        "        return s.length();\n"
+        "    }\n"
+        "}\n", 5);
+
+    run_test_int("String.charAt",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String s = \"Hello\";\n"
+        "        return s.charAt(1);\n"
+        "    }\n"
+        "}\n", 'e');
+
+    run_test_int("String.substring",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String s = \"Hello World\";\n"
+        "        String sub = s.substring(0, 5);\n"
+        "        return sub.length();\n"
+        "    }\n"
+        "}\n", 5);
+
+    run_test_int("String.equals true",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String a = \"test\";\n"
+        "        String b = \"test\";\n"
+        "        if (a.equals(b)) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 1);
+
+    run_test_int("String.equals false",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String a = \"test\";\n"
+        "        String b = \"other\";\n"
+        "        if (a.equals(b)) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test_int("String.compareTo equal",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String a = \"abc\";\n"
+        "        String b = \"abc\";\n"
+        "        return a.compareTo(b);\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test_int("String.compareTo less",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String a = \"abc\";\n"
+        "        String b = \"abd\";\n"
+        "        if (a.compareTo(b) < 0) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 1);
+
+    run_test_int("String.compareTo greater",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String a = \"abd\";\n"
+        "        String b = \"abc\";\n"
+        "        if (a.compareTo(b) > 0) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 1);
+
+    run_test_int("String.indexOf found",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String s = \"Hello World\";\n"
+        "        return s.indexOf(\"World\");\n"
+        "    }\n"
+        "}\n", 6);
+
+    run_test_int("String.indexOf not found",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String s = \"Hello World\";\n"
+        "        return s.indexOf(\"xyz\");\n"
+        "    }\n"
+        "}\n", -1);
+
+    run_test_int("String.contains true",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String s = \"Hello World\";\n"
+        "        if (s.contains(\"World\")) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 1);
+
+    run_test_int("String.contains false",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String s = \"Hello World\";\n"
+        "        if (s.contains(\"xyz\")) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test_int("String.startsWith true",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String s = \"Hello World\";\n"
+        "        if (s.startsWith(\"Hello\")) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 1);
+
+    run_test_int("String.startsWith false",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String s = \"Hello World\";\n"
+        "        if (s.startsWith(\"World\")) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test_int("String.endsWith true",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String s = \"Hello World\";\n"
+        "        if (s.endsWith(\"World\")) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 1);
+
+    run_test_int("String.endsWith false",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String s = \"Hello World\";\n"
+        "        if (s.endsWith(\"Hello\")) { return 1; }\n"
+        "        return 0;\n"
+        "    }\n"
+        "}\n", 0);
+
+    run_test_int("String.toLowerCase length",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String s = \"HELLO\";\n"
+        "        String lower = s.toLowerCase();\n"
+        "        return lower.length();\n"
+        "    }\n"
+        "}\n", 5);
+
+    run_test_int("String.toLowerCase charAt",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String s = \"HELLO\";\n"
+        "        String lower = s.toLowerCase();\n"
+        "        return lower.charAt(0);\n"
+        "    }\n"
+        "}\n", 'h');
+
+    run_test_int("String.toUpperCase charAt",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String s = \"hello\";\n"
+        "        String upper = s.toUpperCase();\n"
+        "        return upper.charAt(0);\n"
+        "    }\n"
+        "}\n", 'H');
+
+    run_test_int("String.trim length",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        String s = \"  Hello  \";\n"
+        "        String trimmed = s.trim();\n"
+        "        return trimmed.length();\n"
+        "    }\n"
+        "}\n", 5);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_string_methods.o b/tests/test_string_methods.o
new file mode 100644
index 0000000..dbada23
Binary files /dev/null and b/tests/test_string_methods.o differ
diff --git a/tests/test_strings.c b/tests/test_strings.c
new file mode 100644
index 0000000..e9dc9a2
--- /dev/null
+++ b/tests/test_strings.c
@@ -0,0 +1,77 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static char* read_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (!file) return NULL;
+    fseek(file, 0, SEEK_END);
+    long size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    char *content = malloc(size + 1);
+    size_t read_bytes = fread(content, 1, size, file);
+    content[read_bytes] = '\0';
+    fclose(file);
+    return content;
+}
+
+int main() {
+    char *source = read_file("examples/12_StringBasics.java");
+    if (!source) {
+        printf("Failed to read file\n");
+        return 1;
+    }
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Parse: OK\n");
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        printf("Semantic error: %s\n", analyzer->error_message);
+        free(source);
+        return 1;
+    }
+
+    printf("Semantic: OK\n");
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        printf("IR generation failed\n");
+        free(source);
+        return 1;
+    }
+
+    printf("IR Gen: OK\n");
+    printf("\nOutput:\n");
+
+    RavaVM_t *vm = rava_vm_create(program);
+    if (!rava_vm_execute(vm, "StringBasics", "main")) {
+        printf("Runtime error: %s\n", vm->error_message);
+        rava_vm_destroy(vm);
+        free(source);
+        return 1;
+    }
+
+    printf("\nExecution: OK\n");
+
+    rava_vm_destroy(vm);
+    free(source);
+    return 0;
+}
diff --git a/tests/test_strings.o b/tests/test_strings.o
new file mode 100644
index 0000000..650f826
Binary files /dev/null and b/tests/test_strings.o differ
diff --git a/tests/test_super.c b/tests/test_super.c
new file mode 100644
index 0000000..5a61309
--- /dev/null
+++ b/tests/test_super.c
@@ -0,0 +1,132 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test_int(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error: %s\n", name, parser->error_message ? parser->error_message : "unknown");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error: %s\n", name, vm->error_message ? vm->error_message : "unknown");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== Super Keyword Tests ===\n\n");
+
+    run_test_int("super.method() basic",
+        "class Parent {\n"
+        "    int getValue() {\n"
+        "        return 10;\n"
+        "    }\n"
+        "}\n"
+        "class Child extends Parent {\n"
+        "    int getValue() {\n"
+        "        return super.getValue() + 5;\n"
+        "    }\n"
+        "}\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        Child c = new Child();\n"
+        "        return c.getValue();\n"
+        "    }\n"
+        "}\n", 15);
+
+    run_test_int("super.method() with args",
+        "class Parent {\n"
+        "    int add(int a, int b) {\n"
+        "        return a + b;\n"
+        "    }\n"
+        "}\n"
+        "class Child extends Parent {\n"
+        "    int add(int a, int b) {\n"
+        "        return super.add(a, b) * 2;\n"
+        "    }\n"
+        "}\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        Child c = new Child();\n"
+        "        return c.add(3, 4);\n"
+        "    }\n"
+        "}\n", 14);
+
+    run_test_int("super.method() chain",
+        "class GrandParent {\n"
+        "    int getValue() {\n"
+        "        return 100;\n"
+        "    }\n"
+        "}\n"
+        "class Parent extends GrandParent {\n"
+        "    int getValue() {\n"
+        "        return super.getValue() + 10;\n"
+        "    }\n"
+        "}\n"
+        "class Child extends Parent {\n"
+        "    int getValue() {\n"
+        "        return super.getValue() + 1;\n"
+        "    }\n"
+        "}\n"
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        Child c = new Child();\n"
+        "        return c.getValue();\n"
+        "    }\n"
+        "}\n", 111);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_switch.c b/tests/test_switch.c
new file mode 100644
index 0000000..c55a7e6
--- /dev/null
+++ b/tests/test_switch.c
@@ -0,0 +1,166 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error: %s\n", name, parser->error_message ? parser->error_message : "unknown");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error\n", name);
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== Switch/Case Tests ===\n\n");
+
+    run_test("Simple switch",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 2;\n"
+        "        int result = 0;\n"
+        "        switch (x) {\n"
+        "            case 1:\n"
+        "                result = 10;\n"
+        "                break;\n"
+        "            case 2:\n"
+        "                result = 20;\n"
+        "                break;\n"
+        "            case 3:\n"
+        "                result = 30;\n"
+        "                break;\n"
+        "        }\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 20);
+
+    run_test("Switch with default",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 99;\n"
+        "        int result = 0;\n"
+        "        switch (x) {\n"
+        "            case 1:\n"
+        "                result = 10;\n"
+        "                break;\n"
+        "            case 2:\n"
+        "                result = 20;\n"
+        "                break;\n"
+        "            default:\n"
+        "                result = 100;\n"
+        "                break;\n"
+        "        }\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 100);
+
+    run_test("Switch fallthrough",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 1;\n"
+        "        int result = 0;\n"
+        "        switch (x) {\n"
+        "            case 1:\n"
+        "                result = result + 10;\n"
+        "            case 2:\n"
+        "                result = result + 20;\n"
+        "                break;\n"
+        "            case 3:\n"
+        "                result = result + 30;\n"
+        "                break;\n"
+        "        }\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 30);
+
+    run_test("Switch first case",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 1;\n"
+        "        int result = 0;\n"
+        "        switch (x) {\n"
+        "            case 1:\n"
+        "                result = 111;\n"
+        "                break;\n"
+        "            case 2:\n"
+        "                result = 222;\n"
+        "                break;\n"
+        "        }\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 111);
+
+    run_test("Switch no match no default",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 99;\n"
+        "        int result = 42;\n"
+        "        switch (x) {\n"
+        "            case 1:\n"
+        "                result = 10;\n"
+        "                break;\n"
+        "            case 2:\n"
+        "                result = 20;\n"
+        "                break;\n"
+        "        }\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 42);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_switch.o b/tests/test_switch.o
new file mode 100644
index 0000000..9e0d85b
Binary files /dev/null and b/tests/test_switch.o differ
diff --git a/tests/test_ternary.c b/tests/test_ternary.c
new file mode 100644
index 0000000..e9d5006
--- /dev/null
+++ b/tests/test_ternary.c
@@ -0,0 +1,140 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include "../runtime/runtime.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int test_count = 0;
+static int pass_count = 0;
+
+static void run_test_int(const char* name, const char* source, int expected) {
+    test_count++;
+
+    RavaLexer_t* lexer = rava_lexer_create(source);
+    RavaParser_t* parser = rava_parser_create(lexer);
+    RavaASTNode_t* ast = rava_parser_parse(parser);
+
+    if (!ast || parser->had_error) {
+        printf("FAIL: %s - Parse error: %s\n", name, parser->error_message ? parser->error_message : "unknown");
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaSemanticAnalyzer_t* analyzer = rava_semantic_analyzer_create();
+    rava_semantic_analyze(analyzer, ast);
+
+    RavaIRGenerator_t* ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t* program = rava_ir_generate(ir_gen, ast);
+
+    RavaVM_t* vm = rava_vm_create(program);
+
+    if (!rava_vm_execute(vm, "Test", "main")) {
+        printf("FAIL: %s - Runtime error: %s\n", name, vm->error_message ? vm->error_message : "unknown");
+        rava_vm_destroy(vm);
+        rava_program_destroy(program);
+        rava_ir_generator_destroy(ir_gen);
+        rava_semantic_analyzer_destroy(analyzer);
+        rava_ast_node_destroy(ast);
+        rava_parser_destroy(parser);
+        rava_lexer_destroy(lexer);
+        return;
+    }
+
+    RavaValue_t result = rava_vm_get_result(vm);
+    int32_t result_int = rava_value_as_int(result);
+
+    if (result_int == expected) {
+        printf("PASS: %s (result=%d)\n", name, result_int);
+        pass_count++;
+    } else {
+        printf("FAIL: %s (expected=%d, got=%d)\n", name, expected, result_int);
+    }
+
+    rava_vm_destroy(vm);
+    rava_program_destroy(program);
+    rava_ir_generator_destroy(ir_gen);
+    rava_semantic_analyzer_destroy(analyzer);
+    rava_ast_node_destroy(ast);
+    rava_parser_destroy(parser);
+    rava_lexer_destroy(lexer);
+}
+
+int main(void) {
+    printf("=== Ternary Operator Tests ===\n\n");
+
+    run_test_int("ternary true condition",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return 1 == 1 ? 42 : 0;\n"
+        "    }\n"
+        "}\n", 42);
+
+    run_test_int("ternary false condition",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        return 1 == 2 ? 42 : 99;\n"
+        "    }\n"
+        "}\n", 99);
+
+    run_test_int("ternary with variables",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 10;\n"
+        "        int y = 20;\n"
+        "        return x < y ? x : y;\n"
+        "    }\n"
+        "}\n", 10);
+
+    run_test_int("ternary min value",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int a = 5;\n"
+        "        int b = 3;\n"
+        "        return a < b ? a : b;\n"
+        "    }\n"
+        "}\n", 3);
+
+    run_test_int("ternary max value",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int a = 5;\n"
+        "        int b = 3;\n"
+        "        return a > b ? a : b;\n"
+        "    }\n"
+        "}\n", 5);
+
+    run_test_int("nested ternary",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 2;\n"
+        "        return x == 1 ? 10 : (x == 2 ? 20 : 30);\n"
+        "    }\n"
+        "}\n", 20);
+
+    run_test_int("ternary in variable assignment",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int x = 5;\n"
+        "        int result = x > 3 ? 100 : 200;\n"
+        "        return result;\n"
+        "    }\n"
+        "}\n", 100);
+
+    run_test_int("ternary with arithmetic",
+        "public class Test {\n"
+        "    public static int main() {\n"
+        "        int a = 4;\n"
+        "        int b = 6;\n"
+        "        return a + b > 8 ? a * b : a + b;\n"
+        "    }\n"
+        "}\n", 24);
+
+    printf("\n=== Results: %d/%d tests passed ===\n", pass_count, test_count);
+
+    return (pass_count == test_count) ? 0 : 1;
+}
diff --git a/tests/test_ternary.o b/tests/test_ternary.o
new file mode 100644
index 0000000..1a497cf
Binary files /dev/null and b/tests/test_ternary.o differ
diff --git a/tests/test_tower_ir.c b/tests/test_tower_ir.c
new file mode 100644
index 0000000..3fad1b1
--- /dev/null
+++ b/tests/test_tower_ir.c
@@ -0,0 +1,56 @@
+#include "../lexer/lexer.h"
+#include "../parser/parser.h"
+#include "../semantic/semantic.h"
+#include "../ir/ir.h"
+#include "../ir/ir_gen.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+static char* read_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (!file) return NULL;
+    fseek(file, 0, SEEK_END);
+    long size = ftell(file);
+    fseek(file, 0, SEEK_SET);
+    char *content = malloc(size + 1);
+    size_t read_bytes = fread(content, 1, size, file); (void)read_bytes;
+    content[size] = '\0';
+    fclose(file);
+    return content;
+}
+
+int main() {
+    char *source = read_file("examples/09_TowerOfHanoi.java");
+    if (!source) return 1;
+
+    RavaLexer_t *lexer = rava_lexer_create(source);
+    RavaParser_t *parser = rava_parser_create(lexer);
+    RavaASTNode_t *ast = rava_parser_parse(parser);
+
+    if (parser->had_error) {
+        printf("Parse error: %s\n", parser->error_message);
+        free(source);
+        return 1;
+    }
+
+    RavaSemanticAnalyzer_t *analyzer = rava_semantic_analyzer_create();
+    if (!rava_semantic_analyze(analyzer, ast)) {
+        printf("Semantic error: %s\n", analyzer->error_message);
+        free(source);
+        return 1;
+    }
+
+    RavaIRGenerator_t *ir_gen = rava_ir_generator_create(analyzer);
+    RavaProgram_t *program = rava_ir_generate(ir_gen, ast);
+
+    if (!program) {
+        printf("IR generation failed\n");
+        free(source);
+        return 1;
+    }
+
+    rava_program_print(program);
+
+    free(source);
+    return 0;
+}