Flaky Tests
Guide to Cypress and Playwright Flaky Tests
What is a flaky test?
A flaky test is a test that did not succeed on the first attempt. The build will fail only occasionally: One time it will pass, another time fail, and the next time pass again, without any changes to the build having been made. Flaky tests are marked with a special badge on the run, spec and individual test levels.
How to activate flaky test detection?
Flaky tests are automatically activated for all types of tests with retries enabled. When a test has retries enabled and doesn't pass on the first attempt, it will be marked as flaky.
Why are flaky tests bad?
A flaky test like this can block the continuous deployment pipeline, making feature delivery slower than it needs to be. Moreover, a flaky test is problematic because it is not deterministic anymore — making it useless. After all, you wouldn’t trust one any more than you would trust a liar.
Flaky tests are expensive to repair, often requiring hours or even days to debug.
In summary, flaky cypress tests are considered harmful because:
You cannot trust them - neither system / component under test nor the test itself is reliable
Even if flaky tests pass, your end users can experience intermittent issues
Flaky tests increase the duration of your test suite
Flaky tests are expensive to repair and maintain
How to get rid of flaky tests?
Your team is arguably the most important factor. As a first step, admit that you have a problem with flaky tests. Getting the whole team’s commitment is crucial! Then, as a team, you need to decide how to deal with flaky tests.
Identify flaky tests
Eliminate Flaky Tests
Examine the outcomes of your runs to see what tests are flaky and eliminate the source of flakiness.
Don't use fixed wait times
Optimize test structure - write smaller tests
Keep tests isolated - use fresh, clean data before each test
Give up and use retries 😛
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