test(sveta): Write tests for median function

Outcome: done

Changed: tests/test_calculator.py:3, tests/test_calculator.py:68-90

Verified by: make verify — exit code 0, 22 tests passed, verification passed.

Findings:
- tests/test_calculator.py:3 — `median` imported alongside `clamp`.
- tests/test_calculator.py:68-90 — `TestMedianFunction` class added with 6 tests: odd-length returns middle element, even-length returns float average, single-element returns that element, empty list raises ValueError, unsorted odd-length sorts correctly, unsorted even-length sorts and returns float average.
- All 6 acceptance criteria addressed: odd-length, even-length (float), single-element, empty (ValueError), unsorted sorting, and existing conventions (retoor header, unittest.TestCase, full type annotations).

Open: none

Confidence: high — verification passed with all 22 tests, coverage confirmed against every acceptance criterion.

Typosaurus-Run: 529efb295dd94e799a5e47a9ef0c6c16
Typosaurus-Node: 341a13e1a6b04e838cc1ff6d643aab85
Typosaurus-Agent: @sveta
Refs: #13

tests/test_calculator.py

@@ -3,7 +3,7 @@
 import math
 import unittest
 
-from src.calculator import clamp
+from src.calculator import clamp, median
 
 
 class TestClampFunction(unittest.TestCase):
@@ -61,3 +61,29 @@ class TestClampFunction(unittest.TestCase):
     def test_nan_returns_nan(self) -> None:
         result = clamp(math.nan, 0, 10)
         self.assertTrue(math.isnan(result))
+
+
+class TestMedianFunction(unittest.TestCase):
+
+    def test_odd_length_returns_middle_element(self) -> None:
+        self.assertEqual(median([1, 3, 5]), 3)
+
+    def test_even_length_returns_float_average_of_two_middle_values(self) -> None:
+        result = median([1, 2, 3, 4])
+        self.assertIsInstance(result, float)
+        self.assertEqual(result, 2.5)
+
+    def test_single_element_returns_that_element(self) -> None:
+        self.assertEqual(median([7]), 7)
+
+    def test_empty_list_raises_value_error(self) -> None:
+        with self.assertRaises(ValueError):
+            median([])
+
+    def test_unsorted_input_sorts_correctly(self) -> None:
+        self.assertEqual(median([3, 1, 2]), 2)
+
+    def test_unsorted_even_length_returns_float_average(self) -> None:
+        result = median([10, 30, 20, 40])
+        self.assertIsInstance(result, float)
+        self.assertEqual(result, 25.0)