An unstable test, sometimes referred to as a Selenium test “flaky test case” or “unstable test,” is a test that, even in cases where the code being tested remains unchanged, yields inconsistent or unpredictable results after several test runs. These tests may pass intermittently, causing confusion and making it difficult to trust the test results. They often fail for seemingly random reasons, even though the underlying code or environment has not changed.
Assume you have a Selenium test that functions well in the majority of cases. However, it fails for one or more particular causes 10% of the time.
This can happen due to various factors such as timing issues, resource limitations, or external dependencies, leading to unpredictable behavior. These flaky tests can slow down the development process, as they require additional time and resources to investigate, potentially masking real issues and reducing the effectiveness of the testing effort.
Your CI/CD process will suffer if your tests are erratic since it may hinder the deployment of new code. We’ll offer some guidance below on how to avoid and correct faulty tests. Check out the Selenium automation testing course to learn more about the concepts of Selenium testing and what flaky selenium tests imply.
What can cause flaky Selenium test?
Flaky tests can occur for a number of causes; the most frequent ones are listed below.
- Timing Problems: Tests that rely on particular timing circumstances, like network delay or UI element loading, may pass or fail sporadically due to minute timing fluctuations.
- Concurrency and Parallelism: When tests are run in parallel, improper isolation or synchronisation might cause them to interfere with one another, producing erratic or inconsistent results.
- External Dependencies: If external services or resources, like databases or APIs, are unavailable or act unexpectedly, tests that rely on them may not pass. For instance, a database might be operating slower than usual, an HTTP call might time out, or there might be TCP problems or delays.
- Race Conditions: Race conditions can happen when numerous threads or processes interact with shared resources or when many tests are running concurrently. When more than one executor attempts to access the same resource, a race condition occurs. This could cause your tests to stall, produce inaccurate findings, or have other issues.
- Data Fluctuations: Tests that employ dynamically generated data, like timestamps or random numbers, may yield varying outcomes across runs, which may lead to the failure of tests or programs that depend on a particular format.
We’ll look at ways to address the reasons for flaky tests in the next section. Combining best practices with technical solutions is necessary to address flaky testing.
Here are some steps for fixing flaky Selenium testing. In addition to offering advice on how to improve performance and dependability, these are best practices for developing and managing Selenium tests.
- Timing and Waits in your Selenium tests
There have been experiments where an implicit or explicit wait was replaced with a sleep function. Using a sleep schedule is not a good idea:
- There’s a chance that your test will wait too long, adding unwarranted time to the entire test.
- It is possible that your test will fail because it does not wait long enough.
Using implicit or explicit waits is a better approach to wait for an element to appear or an action to complete. You can use these routines to set a timeout for a particular event. Instead of requiring a set amount of time to sleep, you must provide a prerequisite that must be satisfied in order for the test to proceed.
- Use Stable Locators
Make sure you use the most robust locator approach for locating DOM elements in your test. Use an identification that is the least likely to change, for instance, if you have a website and you want to interact with a particular piece on the page.
Some websites generate DOM element IDs randomly or dynamically. It is a surefire way to have a flaky test if you use these in yours. Use a more reliable locator instead, like an xpath or css locator.
- Add retry mechanisms
Retry mechanisms are included by default in certain Selenium test frameworks. Should your test framework not facilitate this, you could want to incorporate a retry mechanism within your code. If there was a mistake or an inaccurate outcome, you could want to try the logic again.
This method is more akin to applying a Band-Aid because it doesn’t address the root cause. As a last option, we advise employing this strategy.
- Use Selenium Grid and Parallelism
A local Selenium Grid or a cloud-based Selenium Grid can be used to run several tests concurrently on different browsers. By doing this, tests that fail due to an excessive load on the testing system will be prevented. The likelihood of faulty tests will be decreased by running several tests on multiple machines, ensuring that each test runs in isolation with minimal interference from system resource limitations.
This distributed testing approach not only improves test efficiency but also provides better coverage across different environments, ultimately leading to more reliable results and faster feedback during the development cycle.
Conclusion
To learn more about Selenium testing and gain an in-depth understanding of flaky tests, their causes, and effective ways to manage them, consider exploring a Selenium online course. Flaky tests, which sometimes pass and sometimes fail without any changes to the code, are a common challenge in test automation. They can lead to unreliable results and can make it difficult to assess the true quality of your application.
An online course focused on Selenium testing can teach you the skills needed to identify and fix flaky tests, ensuring your automated testing suite is consistent and dependable. You’ll also learn the best practices for structuring tests to reduce flakiness and maintain stability across different test environments.
In addition to flaky test management, a Selenium online course typically covers essential topics, such as Selenium WebDriver setup, handling different browsers, and integrating with CI/CD tools.
By working through hands-on exercises and real-world examples, you can build expertise in setting up robust and scalable test automation frameworks. Moreover, you’ll learn advanced techniques, such as data-driven testing, cross-browser testing, and effective reporting. This comprehensive training will not only enhance your technical skills but also improve your ability to deliver reliable and efficient automated tests, making you a valuable asset in any QA or development team.
Call to Action
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