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 😛

Fail on Flaky Tests

failOnFlakyTests property is available in Playwright v1.52+, and in @currents/playwright starting from v1.12.3.

Starting with Playwright v1.52, the runner can be configured to exit with an error if any test has been marked as flaky see the official docs. This is particularly useful on CI systems where the presence of flaky tests should block the pipeline.

Configuration

In your playwright.config.ts, enable the option by setting failOnFlakyTests to true (for example, based on the CI environment variable):

import { defineConfig } from '@playwright/test';

export default defineConfig({
  // Exit with an error if any test is marked flaky.
  failOnFlakyTests: Boolean(process.env.CI),
});

Command-Line Option

Alternatively, the same behavior can be enabled via the CLI flag:

# Using Playwright test command
npx playwright test --fail-on-flaky-tests

# Using the Playwright wrapper
npx pwc --fail-on-flaky-tests

# Using the orchestration
npx pwc-p --fail-on-flaky-tests

When this flag is present, the test run will exit with a non-zero status if any tests are detected as flaky, ensuring flaky tests block your CI pipeline.