Among the various types and forms of software testing, regression testing is often surrounded by misunderstandings and uncertainties in its proper application. It is common for upper management not to pay enough attention to it, as they believe that retesting already tested features is unnecessary and overly cautious. Nonetheless, it is undeniable that regression testing serves as a fundamental checkpoint. This form of testing ensures that previously functioning features continue to work as expected, and that new developments do not introduce new problems. Thus, regression testing is essential to ensure that the software ultimately becomes truly valuable to users and that the entire quality assurance process remains reliable and effective.
Due to the complexity and size of the application code, it is often difficult to predict how minor updates or bug fixes will affect the entire system. Such modifications can cause unexpected side effects that negatively impact existing functionality and the software’s stability. In this context, regression testing becomes key. This type of testing is designed to identify and eliminate any negative effects indirectly caused by newly introduced features or changes. Ideally, regression testing should begin early in the software’s implementation phase and be performed regularly throughout the process to ensure software quality and reliability despite later developments, fixes, and updates.
What is the difference between regression testing and retesting?
Regression testing and retesting are two terms often mixed up in software testing. Although they may sound similar at first, they differ significantly in meaning and purpose.
Regression Testing
Regression testing is a type of testing intended to ensure that new code changes—such as updates, bug fixes, or feature additions—do not cause unintended side effects in existing, previously working functionalities. This testing method is critical for maintaining software stability and reliability. During regression testing, testers run extensive test cases covering not only the new code changes but also the entire application. Frequently repeating such tests helps identify potential regression bugs and ensures that new features do not degrade existing functionality. Regression testing is often repeated throughout development cycles, especially after significant code changes, to minimize risks in the software.
Retesting
Retesting, in contrast, is a specific testing process focused on verifying that previously reported and fixed bugs have indeed been resolved. The goal of retesting is solely to validate the bug fix. When a defect is identified and corrected, testers rerun the test cases related to that defect to ensure the issue has been resolved. In retesting, testers run only those test cases directly related to the fixed bugs, making the process specific and targeted. It is performed after each bug fix to confirm its completion.In summary, regression testing checks overall application stability after changes, while retesting focuses only on the corrected bugs. Regression testing is broader and recurring; retesting is specific and carried out after fixes. Both are important but serve different purposes and are applied differently.
How to define entry and exit criteria for regression testing?
The entry and exit criteria for regression testing play an essential role in the testing process, as they determine when regression testing can start and when it can be considered complete. Defining these criteria maintains consistency, ensures the software meets the prerequisites for testing, and clearly signals when testing is finished. It also helps manage resources effectively by allocating time and effort based on these criteria.
Entry Criteria
The conditions that must be met before regression testing can begin:
- Development cycle complete: new features or bug fixes are finished.
- Build stability: the new build is stable and testable.
- Availability of adequate resources and environment: time, personnel, infrastructure, test environment set-up, and necessary tools.
- Focused code scope: regression testing should target modules that have undergone recent code changes. Unaffected modules may be excluded.
- Test cases available: all necessary test scenarios, test cases, and automated tests are ready.
- Test data ready: all needed data is available to testers.
- Access to historical results: prior test cases, plans, and results must be accessible for comparison.
- Clearly defined scope: due to possibly limited resources, prioritize issues by importance and reproducibility to define the regression scope.
Exit Criteria
The conditions that must be fulfilled for regression testing to be considered complete. Defined before testing begins, they may include:
- All test cases executed: every planned scenario and test case has been successfully executed; retesting done if defects were found.
- Zero critical or high-priority defects outstanding; fixes have been validated.
- Test reports completed: results documented and reports prepared.
- Risks addressed: all identified risks and issues handled—for example, prioritizing tests for popular user-facing features.
Regression Testing and Automation
The key to cost-effective and efficient regression testing is finding the right balance between manual and automated methods.
As the project scales, automating regression testing becomes logical—manually running thousands of tests and comparing outputs (spanning thousands of pages) can be overwhelming.
Test automation improves accuracy, reduces human error, and allows continuous 24/7 testing. It saves time and enables testers to focus on critical, high-value testing tasks.
Advantages of automated testing:
- Broader test coverage through increased cases and scenario depth.
- Time savings: repetitive tests run in parallel, giving quick feedback and accelerating the process.
- Better allocation of tester effort: focus on creativity and analysis, not routine execution.
Disadvantages of automation:
- Upfront investment: requires tools and infrastructure.
- Complexity: especially for large and sophisticated systems.
- Maintenance overhead: test scripts need constant care and updates.
Supporting Effective Regression Testing
- Include testers from early development: have them attend code reviews—even without advanced coding knowledge. This keeps them informed and helps expand test suites for affected functionality.
- Focus on targeted test planning: fewer but more effective test cases are better than many unnecessary ones.
- Ensure repeatable processes: run regression tests consistently on the same functionality to ensure reliable results, allowing only minimal variation.
- Continuously improve: regularly evaluate and refine the regression process using test results and feedback.
- Integrate with CI/CT: embed regression testing into Continuous Integration and Continuous Testing pipelines for automatic execution on code changes.
- Add regression to CD pipelines: include automated regression tests in Continuous Delivery test suites to catch deployment-phase errors. Use both short (fast feedback) and long (full coverage) test suites based on priority.
How Regression Testing Can Help Your Business
Maintaining Quality and Customer Satisfaction
Thorough regression testing ensures your software product remains stable and bug-free, boosting user satisfaction and building trust in your brand.
Saving Time and Money
Detecting and fixing bugs early in development is faster and cheaper than addressing issues later in production. Early regression testing improves efficiency and reduces costs.
Regression testing complements ongoing functional testing—it doesn’t replace it. Best practice is to design and execute tests alongside feature specification, then continuously expand regression coverage.
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