Merge pull request 'feat: Add multiply and divide to the calculator' (#3) from typosaurus/2-add-multiply-and-divide-to-the-calculator into main

Reviewed-on: #3

Makefile

@@ -1,2 +1,2 @@
 verify:
-	@python3 -m compileall -q src && echo "verification passed"
+	@python3 -m compileall -q src tests && python3 -m unittest discover -s tests -q && echo "verification passed"

src/calculator.py

@@ -6,3 +6,13 @@ def add(left: int, right: int) -> int:
 
 def subtract(left: int, right: int) -> int:
     return left - right
+
+
+def multiply(left: int, right: int) -> int:
+    return left * right
+
+
+def divide(left: int, right: int) -> int:
+    if right == 0:
+        raise ValueError('division by zero')
+    return left // right

tests/test_calculator.py

@@ -0,0 +1,58 @@
+# retoor <retoor@molodetz.nl>
+
+import unittest
+
+from src.calculator import add, subtract, multiply, divide
+
+
+class TestCalculator(unittest.TestCase):
+
+    def test_add(self) -> None:
+        self.assertEqual(add(2, 3), 5)
+
+    def test_subtract(self) -> None:
+        self.assertEqual(subtract(5, 3), 2)
+
+    def test_multiply_positive(self) -> None:
+        self.assertEqual(multiply(2, 3), 6)
+
+    def test_multiply_negative_left(self) -> None:
+        self.assertEqual(multiply(-2, 3), -6)
+
+    def test_multiply_negative_right(self) -> None:
+        self.assertEqual(multiply(2, -3), -6)
+
+    def test_multiply_both_negative(self) -> None:
+        self.assertEqual(multiply(-2, -3), 6)
+
+    def test_multiply_zero_left(self) -> None:
+        self.assertEqual(multiply(0, 5), 0)
+
+    def test_multiply_zero_right(self) -> None:
+        self.assertEqual(multiply(5, 0), 0)
+
+    def test_multiply_both_zero(self) -> None:
+        self.assertEqual(multiply(0, 0), 0)
+
+    def test_divide_positive(self) -> None:
+        self.assertEqual(divide(6, 3), 2)
+
+    def test_divide_negative_left(self) -> None:
+        self.assertEqual(divide(-6, 3), -2)
+
+    def test_divide_negative_right(self) -> None:
+        self.assertEqual(divide(6, -3), -2)
+
+    def test_divide_both_negative(self) -> None:
+        self.assertEqual(divide(-6, -3), 2)
+
+    def test_divide_floor(self) -> None:
+        self.assertEqual(divide(7, 3), 2)
+
+    def test_divide_zero_numerator(self) -> None:
+        self.assertEqual(divide(0, 5), 0)
+
+    def test_divide_by_zero(self) -> None:
+        with self.assertRaises(ValueError) as cm:
+            divide(5, 0)
+        self.assertEqual(str(cm.exception), 'division by zero')