What is Regression Testing

Regression testing is software testing conducted after a code update to ensure that the update introduced no new bugs. This is because new code may bring new logic that conflicts with the existing code, leading to defects. Usually, QA teams have a series of regression test cases for essential features that they will re-execute each time these code changes occur to save time and maximize test efficiency.

If the project has a version control system, locating the exact component that produces the bug can be more accessible. However, regression testing lets us know exactly where the bug comes from, enabling better troubleshooting. It is a periodic health checkup for the software. Due to its highly repetitive nature, regression testing is a great candidate for automation testing.

Regression testing focuses on verifying whether changes to a software application have introduced new defects or negatively impacted existing functionality.

  1. Purpose: Regression testing has several uses, but its primary function is testing software recently changed. It helps software developers determine whether or not a system can handle changes without compromising efficiency.
  2. Test Suites: Regression tests are typically derived from a set of test cases or test suites that cover the software’s critical and commonly used features. These test cases are run repeatedly to check for any deviations from expected behavior.
  3. Automation: Automated regression testing involves creating scripts or test cases that can be executed automatically during a code change. Automated testing tools can streamline this process and quickly identify issues.
  4. Continuous Integration (CI)/Continuous Deployment (CD): Continuous Integration is the practice of running the steps traditionally performed during Integration, and continuous deployment builds on the foundation of build and test automation established with constant Integration. This helps catch issues early in the development cycle.
  5. Scope: The scope of regression testing can vary depending on the project’s needs. It can involve testing the entire application, specific modules, or critical pathways through the software.
  6. Test Maintenance: As the software evolves, the regression test suite must be updated to reflect application functionality changes. This ensures that the tests remain relevant and practical.
  7. Bug Tracking: When regression testing uncovers issues, such as new defects or regressions, these are typically documented and prioritized for resolution. The goal is to fix any problems before they reach users.

Overall, regression testing is an essential quality assurance practice that helps maintain software reliability and stability throughout its lifecycle, even undergoing ongoing development and improvement.

Examples Of Regression Testing

Keep in mind that regression testing is a practice and method. There isn’t a testing tool for regression testing. Any test developed at the initial launch of a particular feature brought up to run at later releases is already a regression test. You can have regression tests by application attribute and type:

  • Attribute: visual, functional, performance, security
  • Application layer: UI and API
  • Application type: web, mobile, API, and desktop
  • Granularity: end-to-end, Integration, and unit tests (test pyramid)

To perform regular checkups on existing code, regression testing involves:

  • Testers writing and building automated test suites
  • Testers and business analysts filtering out release-specific tests to rerun on affected areas from new releases

Let’s consider a simple example. We have a community-type mobile application where users can share their insights through short posts for others to comment on and interact with. A software engineer wants to add a personalized post-recommendation feature based on the user’s interests and past activity to improve UX further.

After the new feature is written, regression testing ensures the new recommendation feature does not affect the existing part. The test plan might involve running manual or automated regression tests to check the functionality of the current code and if there are any conflicts between the two versions. If any bugs are discovered, they are fixed, and the regression test is rerun until all tests pass.

At a larger scale, companies whose business model revolves around their digital products need regression testing to check up on their core features frequently.