test: add unit tests for _validate_lengths field length guard

testing/backend/unit/test_routes_validate_lengths.py

@@ -0,0 +1,61 @@
+import pytest
+from fastapi import HTTPException
+
+from backend.secuscan.routes import _validate_lengths
+
+
+def test_valid_name_under_255_chars_passes():
+    # Should not raise
+    _validate_lengths(name="a" * 100)
+
+
+def test_valid_description_and_notes_under_2000_chars_passes():
+    # Should not raise
+    _validate_lengths(description="d" * 500, notes="n" * 500)
+
+
+def test_name_exactly_255_chars_passes():
+    # Should not raise — boundary is inclusive
+    _validate_lengths(name="a" * 255)
+
+
+def test_name_over_255_chars_raises_with_detail_message():
+    with pytest.raises(HTTPException) as exc_info:
+        _validate_lengths(name="a" * 256)
+
+    assert exc_info.value.status_code == 400
+    assert exc_info.value.detail == "Resource name exceeds maximum length of 255 characters"
+
+
+def test_description_exactly_2000_chars_passes():
+    # Should not raise — boundary is inclusive
+    _validate_lengths(description="d" * 2000)
+
+
+def test_description_over_2000_chars_raises_http_exception():
+    with pytest.raises(HTTPException) as exc_info:
+        _validate_lengths(description="d" * 2001)
+
+    assert exc_info.value.status_code == 400
+    assert exc_info.value.detail == "Resource description exceeds maximum length of 2000 characters"
+
+
+def test_notes_over_2000_chars_raises_http_exception():
+    with pytest.raises(HTTPException) as exc_info:
+        _validate_lengths(notes="n" * 2001)
+
+    assert exc_info.value.status_code == 400
+    assert exc_info.value.detail == "Resource notes exceeds maximum length of 2000 characters"
+
+
+def test_custom_resource_type_reflected_in_error_message():
+    with pytest.raises(HTTPException) as exc_info:
+        _validate_lengths(name="a" * 256, resource_type="Target policy")
+
+    assert exc_info.value.detail == "Target policy name exceeds maximum length of 255 characters"
+
+
+def test_none_values_for_optional_fields_pass():
+    # All fields default to None — should not raise
+    _validate_lengths()
+    _validate_lengths(name=None, description=None, notes=None)