test-implement-constructor-validation

Automatically generate comprehensive constructor validation tests for service classes that follow the fail-fast principle. This skill ensures every required parameter has a corresponding test that validates the service raises ValueError when that parameter is None.

Fixture Exclusion Pattern: Each validation test excludes the fixture for the parameter being tested:

For a complex service with 5 parameters, follow the same pattern as Example 1 above. Create a test class with fixtures for each parameter, a success case test, and one validation failure test for each required parameter. See references/reference.md for detailed pattern analysis and edge cases.

Auto-generate constructor validation tests from service class signatures. Use when creating tests for new services, validating fail-fast principle, ensuring constructor validation, or testing required parameters. Analyzes service __init__ methods and generates pytest.raises(ValueError) tests for each required parameter. Works with Python service classes following dependency injection pattern. High automation opportunity (100+ test classes use this pattern). Source: dawiddutoit/custom-claude.