Effective Strategies for Handling Flaky Tests in Automated UI Testing

Effective Strategies for Handling Flaky Tests in Automated UI Testing

16 July 2024 Stephan Petzl Leave a comment QA

Flaky tests, which sometimes fail and sometimes pass without any consistent reason, can be a significant source of frustration. They slow down the development and testing process, produce false positives, and often lead to disabling tests to move forward. Here, we provide a structured approach to address flaky tests efficiently.

Identifying Flaky Tests

To manage flaky tests effectively, it’s crucial to identify them accurately. One method is to move suspected tests into quarantine. Repeat these tests multiple times under the same conditions to determine which ones produce inconsistent results. This process helps in isolating truly unstable tests.

Fixing Bad Test Code

Once flaky tests are identified, the next step is to fix the underlying issues in the test code. Common problems include:

  • Lack of isolation
  • Asynchronous behaviors
  • Remote service dependencies
  • Time issues
  • Resource leaks
  • Global states

Addressing these issues involves ensuring proper test isolation, managing asynchronous operations correctly, and avoiding dependencies on external services. For more detailed analysis and solutions, refer to Martin Fowler’s article on Eradicating Non-Determinism in Tests and the academic paper An Empirical Analysis of Flaky Tests.

Improving Test Design

Test design plays a significant role in the stability of tests. Anti-patterns such as relying heavily on end-to-end tests can increase flakiness. Instead, focus on a balanced test pyramid with a mix of unit, integration, and end-to-end tests. End-to-end tests, while good for finding bugs, are more prone to flakiness and should be minimized.

Using Flaky Tests for Bug Discovery

Flaky tests can still be valuable for bug discovery. They help identify issues that might not be apparent through stable tests. However, it’s essential to treat the results of flaky tests with caution and perform thorough analysis to distinguish true bugs from false positives.

Implementing a Re-Run Strategy

A practical approach to managing flaky tests is to implement a re-run strategy. Rerun any tests that fail up to three times. If a test fails consistently, it indicates a real issue. This strategy helps filter out false positives caused by transient issues such as network or timing problems.

Minimizing End-to-End Tests

End-to-end tests are more likely to be flaky due to their complexity and the number of components involved. Minimizing their use and focusing more on unit and integration tests can lead to more stable and reliable test suites.

Leveraging Automation Tools

For those using Protractor/WebDriverJS for end-to-end browser automated UI testing, tools like protractor-flake can help manage flaky tests by automatically rerunning failed tests.

Conclusion

Dealing with flaky tests requires a multifaceted approach, including identifying unstable tests, fixing underlying issues, improving test design, and implementing re-run strategies. By addressing these areas, you can significantly reduce the flakiness of your test suite and enhance the overall reliability of your automated tests.

For teams looking for a robust solution to manage flaky tests, tools like Repeato can be invaluable. Repeato is a no-code test automation tool for iOS and Android that leverages computer vision and AI to create, run, and maintain automated tests quickly and efficiently. Its ease of setup and use makes it an excellent choice for quality assurance, ensuring your apps are thoroughly tested with minimal hassle. Learn more about Repeato on our about page.

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