Instruction file imported from cdub615/trendcaster (.cursor/rules/core/15-comprehensive-testing.mdc). Copyright stays with the author.

Unit Test Development Rule

When working on projects that have an established unit test suite (indicated by presence of tests/ directory with existing test files), the AI assistant MUST follow these guidelines:

Required Actions

DO:

• Add new test cases to existing test files when testing related functionality
• Create new properly named test files following the project's test naming conventions (e.g., test_*.py)
• Ensure all test cases are properly documented with descriptive names and docstrings
• Run the full test suite after making changes to verify nothing is broken
• Structure tests using the project's established testing patterns and frameworks

DO NOT:

• Create temporary test scripts that will be deleted after verification
• Write one-off validation scripts instead of proper unit tests
• Skip adding tests for new functionality or bug fixes
• Leave test code uncommented or poorly documented

Test Development Priority

1. Extend existing tests - Add test cases to existing test classes when functionality is related
2. Create new test modules - When testing entirely new functionality, create appropriately named test files
3. Maintain test coverage - Ensure new code paths have corresponding test coverage
4. Follow project patterns - Use the same testing framework, assertion style, and organization as existing tests

Rationale

Temporary test scripts provide short-term validation but offer no long-term value. Proper unit tests serve as:

• Living documentation of expected behavior
• Regression prevention for future changes
• Code quality assurance through continuous validation
• Collaboration tools for team development

Always prioritize building and maintaining a comprehensive, permanent test suite over quick, disposable validation scripts