test-driven-development

# Test Driven Development ## When to Use Me Use me when: - write production code - add feature - implement - TDD - new function - create endpoint - add method - implement this - write code for Do not use me for: - debug - investigate - analyze error - refactor without changing behavior - documentation - configuration - setup - explore - spike - general programming questions - installation or troubleshooting - framework-agnostic code help - bug investigation (use systematic-debugging first) ## Workflow 1. Identify behavior to implement 2. Write failing test (RED) - one behavior, clear name, real code 3. Verify test fails correctly - MANDATORY, never skip 4. Write minimal code to pass (GREEN) - simplest possible 5. Verify all tests pass - MANDATORY, check other tests too 6. Refactor while staying green (REFACTOR) - clean up only 7. Repeat for next behavior ## Error Handling - Code written before test exists: STOP, request deletion, restart with test - Test passes immediately: Verify test tests the right thing, not existing behavior - Multiple behaviors in one test: Ask to split into separate tests - Refactoring with failing tests: STOP, require green tests first - I'll test after: STOP, TDD requires test first - no exceptions - Keeping code as reference: STOP, delete means delete ## Tools The following tools are available to enforce TDD: - `check-test-exists` - Verify test file exists before writing implementation - `validate-tdd-cycle` - Check if TDD cycle was followed via git history - `analyze-git-order` - Analyze commit order to verify test-first approach Use these tools to validate TDD compliance automatically. ## Quick Tests Should trigger: - Create a new API endpoint - Add user authentication - Implement a new endpoint with tests first - Implement payment processing - Write a login function Should not trigger: - Debug this error - Investigate why tests fail - Refactor this function (no behavior change) - Update the documentation - Configure the server Functional: - Write test before implementing login feature - Follow TDD for new endpoint ## References - `references/workflow-playbook.mdx` - RED-GREEN-REFACTOR cycle details - `references/anti-patterns.mdx` - Testing anti-patterns to avoid ## The Iron Law ``` NO PRODUCTION CODE WITHOUT A FAILING TEST FIRST ``` Write code before the test? Delete it. Start over. ## Verification Checklist Before marking work complete: - [ ] Every new function/method has a test - [ ] Watched each test fail before implementing - [ ] Each test failed for expected reason - [ ] Wrote minimal code to pass each test - [ ] All tests pass - [ ] No errors or warnings in output - [ ] Edge cases covered