Common Causes of Flaky Tests
- Asynchronous operations not handled properly
- Timing issues and race conditions
- Dependency on external systems or shared test data
- Unstable test environments or network conditions
- Improper cleanup between test runs
- UI element timing and rendering delays
Detection Techniques
- Run tests multiple times in isolation to identify inconsistent behavior
- Use test rerun plugins to detect patterns of flakiness
- Analyze CI logs and failure trends
- Tag and quarantine flaky tests for further investigation
Tools for Identifying Flaky Tests
- Jenkins Flaky Test Handler Plugin
- TestNG IRetryAnalyzer
- JUnit RetryRule
- Cypress flaky test detection
- Allure TestOps for test history analysis
Code Snippets for Handling Flaky Tests
Example. Retry logic in TestNG (Java):
public class RetryAnalyzer implements IRetryAnalyzer {
private int count = 0;
private static final int maxTry = 3;
public boolean retry(ITestResult result) {
if (count < maxTry) {
count++;
return true;
}
return false;
}
}
Best Practices for Resolving Flaky Tests
- Use explicit waits instead of static sleeps
- Isolate test data and avoid shared state
- Mock external dependencies where possible
- Ensure proper setup and teardown of test environments
- Run tests in clean environments (e.g., containers)
- Maintain detailed logs and screenshots for debugging
Conclusion
Flaky tests should be treated as high-priority issues. By identifying root causes, using the right tools, and following best practices, teams can significantly improve the reliability and trustworthiness of their automated test suites.