superpowers-tdd_skill

Overview

This skill enforces a tests-first discipline (red → green → refactor) for Python projects to reduce regressions and make change safer. I guide you to add focused unit tests or minimal verification when full tests are impractical. The goal is predictable, test-protected changes when implementing features, fixing bugs, or refactoring.

How this skill works

I inspect the target change and recommend a concrete test or verification that captures the desired behavior before implementing code. I prioritize small, behavior-driven tests that fail first, then show the minimal implementation to pass them, followed by refactoring while keeping tests green. When unit tests are impossible, I suggest reproducible verification scripts, integration checks, or manual reproduction steps.

When to use it

• Implementing a new feature that can be covered by unit tests
• Fixing a bug — add a regression test whenever practical
• Refactoring code to preserve behavior with tests first
• When preparing critical code paths for deployment
• When introducing logic that could break existing behavior

Best practices

• Follow red → green → refactor for every change
• Keep tests focused: one behavior per test and behavioral names
• If unit tests are hard, provide a minimal verification script or integration test
• Document what tests were added/changed, how to run them, and exactly what they prove
• Run the relevant test subset and linters as part of your change validation

Example use cases

• Add a unit test that reproduces a reported bug, implement the fix, and keep the test as a regression guard
• Write a failing unit test for a new API response shape, implement minimal code to pass, then refactor for clarity
• Refactor a legacy module: write tests covering current behavior, refactor with confidence, remove no tests without replacement
• Create a small script that reproduces an intermittent integration failure when unit tests cannot simulate the environment
• Add end-to-end checks for a critical workflow and include them in CI as smoke tests