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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.
Run Summary with 1 flaky test detected

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

Use our top-flaky-tests Insights to see the tests with the highest flakiness rate.
Flaky Tests Insights

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 😛