tdd
Test-Driven Development
Philosophy
Core principle: Tests should verify behavior through public interfaces, not implementation details. Code can change entirely; tests shouldn't.
Good tests are integration-style: they exercise real code paths through public APIs. They describe what the system does, not how it does it. A good test reads like a specification - "user can checkout with valid cart" tells you exactly what capability exists. These tests survive refactors because they don't care about internal structure.
Bad tests are coupled to implementation. They mock internal collaborators, test private methods, or verify through external means (like querying a database directly instead of using the interface). The warning sign: your test breaks when you refactor, but behavior hasn't changed. If you rename an internal function and tests fail, those tests were testing implementation, not behavior.
See tests.md for examples and mocking.md for mocking guidelines.
Anti-Pattern: Horizontal Slices
DO NOT write all tests first, then all implementation. This is "horizontal slicing" - treating RED as "write all tests" and GREEN as "write all code."
This produces crap tests:
- Tests written in bulk test imagined behavior, not actual behavior
More from rockclaver/systemcraft
refactor-codebase
Incrementally refactor and rearchitect a codebase toward a scalable structure using a phased plan. Use when the user wants to restructure code, improve architecture, reduce coupling, reorganize modules, or migrate toward a cleaner design without breaking the working system.
16code-graph
Builds and maintains a `.claude/codegraph.md` index of a codebase — a structured map of every module with purpose, key exports, and dependencies — so the agent can navigate any repo by reading one file instead of scanning dozens. Use when starting work on an unfamiliar codebase, when asked to index a repo, when context costs are high from repeated scans, or at the start of any task that will touch multiple files.
15find-code
Locate files and code using grep and shell scripts — never by AI scanning. Returns exact file paths and line numbers so the agent can jump directly to the location. Use whenever the agent needs to find a function, class, variable, import, file, or any pattern in the codebase. Code and file discovery must always be a tool call, never an AI guess.
15dockerize-and-deploy
Dockerize a repository and produce production-grade deployment scripts, a docker-compose setup with properly configured volumes, and a pre-flight validation shell script. Use when the user wants to containerize an app, add Docker support, write a deployment pipeline, set up docker-compose, configure volumes, or deploy to production with Docker.
15grill-me
Interview the user relentlessly about a plan or design until reaching shared understanding, resolving each branch of the decision tree. Use when user wants to stress-test a plan, get grilled on their design, or mentions "grill me".
14prd-to-plan
Turn a PRD into a multi-phase implementation plan using tracer-bullet vertical slices, saved as a local Markdown file in ./plans/. Use when user wants to break down a PRD, create an implementation plan, plan phases from a PRD, or mentions "tracer bullets".
14