Two focused testing skills:
/tdd— Test-first development. Write tests before the implementation exists; tests drive the design through a strict Red → Green → Refactor cycle./retrofit-tests— Coverage for existing code. Systematically add unit tests to a source file you've already written, one unit at a time.
# Session-only (for testing)
claude --plugin-dir ./plugins/programming-tools
# Permanent install — via this repo's marketplace (run from the repo root)
claude plugin marketplace add .
claude plugin install programming-tools@local # then restart Claude Code/tdd <description of what to implement>
/retrofit-tests <source-file>
testing/
├── .claude-plugin/
│ └── plugin.json
├── references/ # shared language references
│ ├── python.md
│ ├── javascript.md
│ ├── typescript.md
│ ├── rust.md
│ ├── r.md
│ └── c_cpp.md
└── skills/
├── tdd/
│ └── SKILL.md
└── retrofit-tests/
└── SKILL.md