Review Test Quality

When reviewing tests in a PR:

1. Check that tests cover the actual behavior change, not just that code runs without errors.
2. Check test names: do they describe the expected behavior? Would a failing test name tell you what broke?
3. Check for missing edge cases: empty inputs, nulls, boundary values, error paths.
4. Check test independence: does each test set up its own state? Would tests pass in random order?
5. Check assertions: are they specific? “expect(result).toEqual({…})” is better than “expect(result).toBeTruthy()”.
6. Check for over-mocking: are internal modules mocked when they could be tested directly?
7. Verify tests aren’t just snapshots of current behavior disguised as meaningful assertions.