Test-Driven Development

I want to implement {{featureDescription}} using TDD.

**Tech:** {{testFramework}} for testing, {{language}} codebase

**Step 1 — Write tests first:**
- Create test file at {{testFilePath}}
- Write tests for these behaviors:
  {{expectedBehaviors}}
- Include edge cases: {{edgeCases}}
- Use descriptive test names: "should {{behavior}} when {{condition}}"
- All tests should FAIL initially (red phase)

**Step 2 — Run the tests:**
- Execute {{testCommand}} and confirm they all fail for the right reasons
- Show me the output

**Step 3 — Implement the minimum code to pass:**
- Write the implementation at {{implFilePath}}
- Write only enough code to make the tests pass — no extra features
- Run tests again to confirm they all pass (green phase)

**Step 4 — Refactor if needed:**
- Clean up the implementation while keeping all tests green
- Run the full test suite to check for regressions

Do each step sequentially. Show me the test output after each phase.