Deterministic tests > Written instructions
Anything that should be checked automatically should have a test case:
- Checking behavior → Unit and integration tests
- Checking formatting → Formatters and linters
- Checking types → Static type checkers
- Checking API contracts → Schema validation
- Checking edge cases → Targeted tests
- Checking regressions → Regression tests
- Checking security → Static analysis and security scans
Don't waste tokens telling an agent to follow rules you could enforce with deterministic tests.