Troubleshooting Flaky and Hanging Serenity BDD Tests at Scale

Details: Category: Testing Frameworks; By Mindful Chase; 24.Jul; Hits: 6

Serenity BDD is a robust testing framework that facilitates automated acceptance and regression testing for enterprise-level applications. Despite its powerful reporting and integration capabilities with Cucumber, JUnit, and Selenium, teams often encounter nuanced problems when scaling test suites. One particularly elusive issue is the inconsistent execution or hanging of tests in CI/CD environments—especially when running large feature sets in parallel or integrating with containerized pipelines. These problems not only slow down feedback loops but can also undermine confidence in automated quality gates.

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Serenity BDD Overview in Enterprise Testing

Key Features of Serenity BDD

Serenity BDD provides living documentation, seamless BDD support, and advanced WebDriver management. It integrates with popular test runners like JUnit 5, Cucumber, and RestAssured. The framework emphasizes clean separation between business-readable requirements and executable specifications.

Enterprise Adoption Challenges

In large codebases, Serenity tests can become brittle due to:

Improper use of PageObjects or step definitions
Parallel test interference in Selenium sessions
Incorrect lifecycle management across multiple story files

Root Cause of Intermittent Test Failures

Thread Contention in Parallel Test Execution

Serenity uses a shared WebDriver session unless explicitly configured otherwise. When tests run in parallel (e.g., via Maven Surefire or Gradle), race conditions or session clobbering can occur, leading to random failures or hangs.

serenity.driver.reuse.policy=never
serenity.parallel.threads=4
serenity.parallel.execution.enabled=true

Incorrect WebDriver Lifecycle Handling

Tests that do not close or reset browser sessions can cause stale element references or memory leaks. This is amplified in long-running CI/CD pipelines where garbage collection is not aggressive enough to reclaim idle sessions.

Diagnosing Serenity BDD Failures

Logging and Debug Configuration

Enable debug mode in Serenity to capture verbose logs:

serenity.logging=VERBOSE
serenity.verbose.steps=true
serenity.dry.run=false

Also configure your test runner to include thread info in logs. In Gradle:

testLogging {
  showStandardStreams = true
  events "passed", "failed"
}

Analyzing HTML Reports

Serenity reports generate detailed breakdowns of execution flow. Review the timing of each step and capture screenshots to detect anomalies. Pay attention to flaky steps with erratic durations.

Fixing Common Serenity BDD Issues

Issue: Tests Hanging on Jenkins or GitHub Actions

This usually stems from headless browser misconfigurations or shared WebDriver states. Fix by enforcing headless Chrome with proper flags:

chrome.switches=--no-sandbox,--headless,--disable-gpu,--window-size=1920,1080

Issue: WebDriver is Null or Closed Unexpectedly

This typically occurs when tests execute across multiple threads without isolation. Set WebDriver to create a new session per test:

webdriver.driver=reuse.policy=never

Stabilizing CI/CD Execution

Set JVM heap size explicitly: -Xmx2g -Xms512m
Use container-based browsers (e.g., via Selenium Grid or Selenoid)
Avoid mixing JUnit and Cucumber runners in the same module

Best Practices for Large Serenity BDD Suites

Keep step definitions atomic and stateless
Split test execution across categories or tags using Maven profiles
Use Serenity Screenplay for better abstraction in complex flows
Use the @WithTag annotation for modular test orchestration
Enable reporting only in one parallel thread to avoid I/O conflicts

Conclusion

Serenity BDD is highly extensible, but when used at scale without strict architectural discipline, it can lead to flaky or non-deterministic test behavior. By isolating WebDriver usage, structuring tests for parallel execution, and tuning Serenity configurations, teams can dramatically improve reliability and execution time in CI environments. For long-term success, treat Serenity not just as a test tool—but as part of your application delivery architecture.

FAQs

1. Why do Serenity BDD tests fail only in CI but pass locally?

Differences in environment variables, headless browser settings, or parallel execution setup can introduce timing issues or race conditions that do not manifest locally.

2. How can I safely run Serenity tests in parallel?

Ensure that WebDriver sessions are not shared, use isolated test data, and configure serenity.parallel.execution.enabled=true with unique browser contexts.

3. What's the benefit of the Screenplay pattern in Serenity?

Screenplay promotes reusable, composable interactions over rigid PageObjects, making test flows more maintainable and easier to debug at scale.

4. How can I manage test flakiness in Serenity?

Use retry logic for known flaky steps, monitor step durations, and validate WebDriver cleanup between tests. Also tag unstable tests for exclusion in critical pipelines.

5. Can I integrate Serenity BDD with REST APIs?

Yes, Serenity integrates natively with RestAssured, allowing you to test API flows with the same reporting and assertion capabilities as UI tests.

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