🎯 𝐋𝐞𝐭’𝐬 𝐭𝐚𝐥𝐤 𝐚𝐛𝐨𝐮𝐭 𝐅𝐥𝐚𝐤𝐲 𝐓𝐞𝐬𝐭𝐬 – 𝐭𝐡𝐞 𝐬𝐢𝐥𝐞𝐧𝐭 𝐩𝐫𝐨𝐝𝐮𝐜𝐭𝐢𝐯𝐢𝐭𝐲 𝐤𝐢𝐥𝐥𝐞𝐫 𝐢𝐧 𝐭𝐞𝐬𝐭 𝐚𝐮𝐭𝐨𝐦𝐚𝐭𝐢𝐨𝐧.

You know the ones:
🔁 They pass.
❌ Then they fail.
✅ Then magically pass again.
All without a code change.

🤯 Why are they so dangerous?

They break trust in your test suite
Waste hours of debugging
Block CI/CD pipelines
Lead to “Ignore this test, it always fails 😒”

🛠 Real-world causes I’ve seen:

Timing issues Example: wait_for_element() didn’t wait long enough in slow environments
Data dependency A test passes locally but fails in CI because shared data is already modified
3rd-party services API mock wasn’t stable, external service had rate-limiting
Environment drift Works on Chrome vX, fails on vX+1
Bad Locator Find several web elements (not unique)
Fails only when run in parallel

✅ How to fight flakiness:
🔹 Use explicit waits, not hard sleeps
🔹 Reset or isolate test data
🔹 Add retries ONLY where absolutely needed (@flaky, rerunfailures) - here need to be very carefully
🔹 Log and analyze fail patterns over time
🔹 Isolate flaky tests and flag them for review
🔹 Use mocks to simulate unstable services
🔹 Run tests in consistent, clean environments (Docker, CI agents)

💬 A flaky test is worse than no test at all - because it lies to you.