Tdd London Chicago

What it does

This skill, "Tdd London Chicago," provides guidance and a framework for implementing Test-Driven Development (TDD) using two distinct approaches: the Chicago ("Classicist") and London ("Mockist") schools of thought. It helps AI agents select an appropriate testing style based on the code being developed – favoring real objects and state verification in Chicago, and mocks and interaction verification in London. The skill also suggests agent coordination for test generation, implementation, and refactoring.

When to use it

• When starting a new feature using a test-first approach.
• During refactoring of existing code where increased test coverage is desired.
• To guide teams learning or reinforcing TDD practices.
• When deciding between mocking external dependencies versus testing with real objects.

Key capabilities

• Style Selection: Guides the AI agent in choosing between Chicago (state-based) and London (interaction-based) TDD styles based on code type.
• TDD Cycle Guidance: Provides a structured approach to the Red-Green-Refactor cycle.
• School Comparison: Offers a comparison of the Chicago and London approaches, highlighting their differences in collaborators, verification methods, isolation levels, refactoring ease, and design feedback.
• Agent Coordination: Suggests using specific agent tools (qe-test-generator, qe-test-implementer, qe-test-refactorer) to automate different phases of the TDD process.

Example prompts

• "I'm starting a new feature for calculating shipping costs. Should I use Chicago or London style?"
• "Implement the 'Red' phase for testing this function."
• "Refactor this code while ensuring all tests remain green."

Tips & gotchas

• The skill emphasizes that tests should drive design, not just verify it.
• Always ensure tests fail initially to confirm they are actually testing something.
• Write the minimal amount of code necessary to pass each test – avoid adding unnecessary features during the "Green" phase.