test-driven-development

Write tests first for complex logic. Test fails before code is written.

• Test-Driven Development (TDD) for complex logic
• Write test first, watch it fail, then write minimal code to pass
• Ensures tests verify real behavior, not implementation

• WHEN WRITING TESTS: NO CODE WITHOUT A FAILING TEST FIRST
• Core principle: If you didn't watch the test fail, you don't know if it tests the right thing
• Red-Green-Refactor cycle: fail → verify → pass → refactor
• Tests must be minimal, clear, and show intent
• Mandatory failure verification before green
• No adding features beyond test requirement
• Refactor only after test passes and remains green
• Manual testing or typecheck/lint only when skipping TDD

1. 1.Write failing test first (RED)
2. 2.Verify test fails correctly (MANDATORY)
3. 3.Write minimal code to pass (GREEN)
4. 4.Verify test passes and no other tests break (MANDATORY)
5. 5.Refactor only after green (clean up, no new behavior)
6. 6.Repeat for next feature