Write Tests

Generate tests that catch real bugs and survive refactors. Every test should answer: what behavior breaks if this test fails?

Step 1: Read the Code

Before writing any test, understand the code under test. If the user provides a file or function, read it first.

What to identify	Why it matters	Watch out for
Inputs	These become your test parameters	Assuming only happy-path inputs
Outputs / return values	These are your assertions	Testing internal state instead of outputs
Side effects	These need mocking or verification	Missing async side effects, event emissions
Edge cases	These are where bugs hide	null, undefined, empty arrays, boundary values, concurrent calls
Error paths	These need explicit test coverage	Only testing success cases

Match the code to the right kind of test.