fix: reject negative values in radix sort

.vscode/settings.json

@@ -1,5 +1,6 @@
 {
     "githubPullRequests.ignoredPullRequestBranches": [
         "master"
-    ]
+    ],
+    "python-envs.defaultEnvManager": "ms-python.python:system"
 }

sorts/radix_sort.py

@@ -22,6 +22,10 @@ def radix_sort(list_of_ints: list[int]) -> list[int]:
     >>> radix_sort([1,100,10,1000]) == sorted([1,100,10,1000])
     True
     """
+
+    if any(i < 0 for i in list_of_ints):
+        raise ValueError("radix_sort only supports non-negative integers")
+
     placement = 1
     max_digit = max(list_of_ints)
     while placement <= max_digit:

sorts/test_radix_sort.py

@@ -0,0 +1,55 @@
+import pytest
+
+from sorts.radix_sort import radix_sort
+
+
+def test_radix_sort_basic():
+    assert radix_sort([0, 5, 3, 2, 2]) == [0, 2, 2, 3, 5]
+
+
+def test_radix_sort_already_sorted():
+    values = [1, 2, 3, 4, 5]
+    assert radix_sort(values) == [1, 2, 3, 4, 5]
+
+
+def test_radix_sort_reverse_sorted():
+    values = [5, 4, 3, 2, 1]
+    assert radix_sort(values) == [1, 2, 3, 4, 5]
+
+
+def test_radix_sort_duplicates():
+    values = [4, 2, 4, 1, 2, 4]
+    assert radix_sort(values) == [1, 2, 2, 4, 4, 4]
+
+
+def test_radix_sort_zero():
+    assert radix_sort([0]) == [0]
+
+
+def test_radix_sort_multiple_zeros():
+    assert radix_sort([0, 5, 0, 2, 3]) == [0, 0, 2, 3, 5]
+
+
+def test_radix_sort_different_digit_lengths():
+    values = [1, 1000, 10, 100, 10000]
+    assert radix_sort(values) == [1, 10, 100, 1000, 10000]
+
+
+def test_radix_sort_large_numbers():
+    values = [999999, 123456, 1000000, 42]
+    assert radix_sort(values) == [42, 123456, 999999, 1000000]
+
+
+def test_radix_sort_negative_number():
+    with pytest.raises(ValueError):
+        radix_sort([-1, 5, 3])
+
+
+def test_radix_sort_multiple_negative_numbers():
+    with pytest.raises(ValueError):
+        radix_sort([-10, -5, 0, 5])
+
+
+def test_radix_sort_matches_sorted():
+    values = [170, 45, 75, 90, 802, 24, 2, 66]
+    assert radix_sort(values) == sorted(values)