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How Frequently Should You Run Your Regression Tests?

Maria Homann

Maria Homann

Deciding how often to run your regression tests can be a challenge. Particularly when you've automated your regression suite, and you are more free to decide the frequency. In this blog, we provide an overview of which events or circumstances should trigger regression testing.

Regression testing is a crucial component of software testing. 

Regression testing should be integrated into your software development and maintenance cycle at several stages to ensure the continued performance, functionality, and stability of your applications.

Here are the primary scenarios when regression testing is essential:

  1. After every major code change: Any significant modification to the codebase, whether it’s adding new features, fixing bugs, or making performance enhancements, can introduce unforeseen issues in other parts of the application. Regression testing after these changes helps ensure that the new code integrates well with the existing code without causing disruptions.

  2. Before releases: Before any software release, including major launches, minor updates, or patches, regression testing is crucial to ensure that the changes made during the development cycle haven't adversely affected the application. This practice helps in identifying critical issues before they impact the end-user.

  3. After bug fixes: Once a bug has been identified and fixed, regression testing should be conducted to ensure that the fix hasn’t introduced new bugs or affected the functionality of unrelated features. This is especially important for complex software systems where different components are tightly interconnected.

  4. When integrating third-party tools or APIs: Adding or updating third-party tools, libraries, or APIs can lead to compatibility issues with the existing system. Regression testing ensures that these integrations do not disrupt the application’s operations or user experience.

  5. After environment changes: Changes in the underlying environment, such as updates to the operating system, changes in configurations, or hardware upgrades, can impact the software’s performance or functionality. Regression testing in these scenarios verifies that the application remains stable across different environments.

  6. During Continuous Integration/Continuous Deployment (CI/CD) processes: In CI/CD environments, where code changes are frequent and incremental, regression testing should be automated and run as part of the continuous integration pipeline. This allows for immediate feedback and quick identification of issues introduced by recent changes.

  7. Periodically for legacy systems: For applications that are in maintenance mode or not actively developed, periodic regression testing is advisable, especially when these systems interact with other software that is frequently updated. This proactive approach helps in ensuring that legacy systems remain compatible and functional over time.

As a rule of thumb, you should run your regression tests as often as possible.

The picture below might be a useful analogy: Every time you let a bug out the door, you’ll want to make sure you haven’t let a swarm of new bugs in the door.

regression testing

In other words, your regression suite should ideally be run whenever a change is made to the code. If your software system is large and complex, this is only possible to do with automation.

P.S. regression testing shouldn't be confused with retesting - here's the differences between retesting vs regression testing.

This goes particularly for agile testing teams, where the goal is to get new updates and features tested and released as fast as possible.

There are two ways of ensuring that your tests are run at the desired frequency: You can either run them on-demand or on a schedule. Scheduled tests are ideal because they ensure consistent feedback on contributed code, and won’t be forgotten or overlooked as a result of other priorities.

Related reading: Regression testing best practices

If, however, your test automation tool does not provide you with the option to schedule tests, you should as a minimum run your regression suite in connection with major releases, emergency fixes and incremental code changes.

But remember that regressions don’t just occur when you submit a change. They can occur in connection with database or system updates, new browser versions, and other changes that are outside your knowledge, and perhaps also out of your hands.

This is why finding a tool that allows you to schedule your tests is ideal.

To learn more about what to look for in a regression test automation tool, see our checklist for evaluating regression testing tools or download our whitepaper below to learn everything you need to know about regression testing in agile teams.

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