A passing test suite is supposed to mean "safe to ship." But plenty of teams have a wall of green checks and still ship regressions every week. The tests aren't lying on purpose — they're just testing the wrong things, or nothing at all.
Green doesn't mean covered
The most common trap is coverage as a vanity metric. Ninety percent line coverage sounds great until you notice most of it comes from tests that assert almost nothing — they execute code without checking the outcome. Coverage measures what ran, not what was verified.
Ask a sharper question: if this feature broke, would a test fail? If you can't answer yes for your critical paths, your suite is decorative.
Flaky tests train you to ignore failures
A suite that fails randomly is worse than no suite. Once "just re-run it" becomes the team reflex, real failures get waved through alongside the noise. Flakiness isn't a minor annoyance — it quietly destroys the entire point of automation.
Stability is a feature. Fix flaky tests the moment they appear:
- Replace arbitrary waits with explicit conditions
- Isolate tests so they don't share state
- Control time, randomness, and network
What actually works
- Test behavior, not implementation. Assert what the user experiences, so refactors don't break tests and real bugs do.
- Cover the critical paths first. The signup, the checkout, the thing that makes you money.
- Keep it fast and stable. A suite developers trust is one they'll actually keep green.
Automation is only as good as the confidence it earns. Build the suite that fails loudly when it should — and stays silent when it shouldn't.