Flaky-test exercise (Module 15)

flaky.test.js is deliberately flaky: it passes sometimes and fails sometimes, with no change to the code or the page. fixed.test.js is the same test, fixed. Neither runs in npm test or CI.

Both open slow-status.html, a tiny local page, so the exercise needs no network.

1. Run the flaky test 20 times and count the failures. Mocha has no repeat option, so use a loop:

   for i in $(seq 1 20); do npx mocha tests/flaky/flaky.test.js > /dev/null 2>&1 && echo pass || echo FAIL; done
   

2. Look at a failure: the message, and the screenshot, page source, and console log that the failure hook saves in test-results/.

3. Write down the root cause: timing, shared state, test data, or environment.

4. Fix it without reading fixed.test.js, then compare.

5. Run your fix 50 times with the same loop (seq 1 50) to show it is reliable.

The evidence for Evidence 15 is your written root cause, your fix, and the two runs.

Never "fix" a flaky test by adding retries or a longer sleep. That hides the variation instead of removing it. Wait explicitly for the condition the test needs.

View this document on GitHub practice-repo/tests/flaky/README.md