Test writer for untested legacy code

An agent reads an untested module, writes characterization tests that lock in current behavior, and runs them until they pass.

Tools

• Cursor
• Claude Code

How to set it up

1. 1Pick one module with no tests.
2. 2Ask the agent to write tests describing what the code does today, not what it should do.
3. 3Have it run the test suite and fix the tests (not the code) until green.
4. 4Review the tests, commit them, then refactor with a safety net.