Best Practices of Regression Testing: A Comprehensive Handbook

An engineer working on his computer

When it comes to the various types and forms of software testing, regression testing tends to be surrounded by a cloud of misunderstanding and misapplication. Often, it lacks attention from top-level management, who may think of testing already tested features as unnecessary paranoia. Still, it is indisputable that this process serves as a crucial double-check, ensuring the delivery of valuable software to users.

The complexity and size of application code often make it difficult to foresee the impact of minor updates or bug fixes. This is where regression testing comes in; ideally, it should start as early as possible in your project. Regression testing can be compared to the cement that binds the bricks of your application, ensuring its structural integrity. Just as cement keeps each brick in place, regression testing ensures that new additions to your application integrate seamlessly, reinforcing its stability and preventing any potential collapse when new components are introduced.

What is the difference between Regression Testing and Retesting?

Regression testing and retesting are two terms that are often confused in the world of software testing. While they may sound similar, they have distinct meanings and purposes.


Retesting is performed to validate that a previously reported defect has been fixed correctly after it has been resolved by the development team. It focuses on retesting the specific test cases that initially uncovered the defect to confirm that the issue no longer exists. Retesting is also known as confirmation testing.

Regression testing

On the other hand, regression testing is performed to ensure that modifications or additions to an existing software application have not introduced new defects or negatively impacted the existing functionality. The primary goal of regression testing is to identify any unintended side effects caused by the changes.

Regression testing is a broader concept that involves retesting both modified and unchanged parts of the software to ensure overall stability. Retesting focuses on verifying the resolution of a specific reported defect.

How do you decide the entry and exit criteria for regression testing?

Deciding the entry and exit criteria for Regression Testing helps maintain consistency in the testing process, ensures that the software meets the necessary prerequisites for testing, and provides a clear indication of when testing is finished. It also can help in managing resources effectively, as you can allocate time and effort based on the established criteria.

Entry criteria establish the conditions that must be met before starting regression testing:

  • Adequate resources and infrastructure: regression testing relies on the availability of resources, including time, team members, and necessary infrastructure.
  • Impactful code changes: focus on regression testing for modules that have been impacted by recent code changes. If a particular module remains unaffected, there is no need to include it in the regression testing process.
  • Availability of test data and results: regression testing requires access to previously executed test cases or plans and their corresponding results. Having this historical data allows for a meaningful comparison to assess the current behavior of the system.
  • Aim for resolving issues: when there is no goal to fix the problems identified during regression testing, the investment in this testing approach may not yield significant benefits.

In determining the exit criteria, you need to strike a fine balance between what you can cover as part of the Regression Testing and some calculated risk.

The risk calculation is done by considering both the technical aspects and the business knowledge of the product, such as:

  • Prioritizing testing the features that are popular among users: technical areas of the product that have stood the test of time and have been known to be good on the quality reports are the ones you can choose to live with some risk.
  • Bugs reported by customers and internal teams in the past can also provide valuable insights.
Code on the computer screen

Regression and Automation Testing

The key to cost-effective, productive regression testing is finding the right balance between the manual and automated approaches that deal with different issues.

As your project expands, it becomes more logical to automate regression testing because it can be challenging to manually conduct thousands of tests and compare the results, which could generate thousands of pages of output.

Test automation helps increase precision, minimize human errors, and allows uninterrupted 24/7 testing. This approach helps save a lot of time, allowing testers to concentrate on critical areas that require their full attention.

Benefits of Automated testing

  • Increased test coverage: allows for a wider scope of testing by executing a larger number of test cases and scenarios.
  • Time savings: automated testing significantly reduces the time required to execute repetitive and time-consuming test cases. Through the power of automation, tests may be done concurrently, executing numerous test cases at the same time and generating quick results, accelerating the whole testing process.

Automating regression testing allows testers to focus their mental energy on tasks that demand critical thinking and creativity.

Disadvantages of Automated testing

  • Initial investments: requires an initial investment in specialized software and equipment.
  • Complexity: can be complex and difficult to set up, especially for large and complex systems.
  • Maintenance: requires regular maintenance and updating of the test scripts.

Ways to support Regression testing

  • Include testers: Testers should actively participate in code review meetings, even if they have limited coding knowledge. Involvement in code reviews helps testers stay informed about code changes and enables them to concentrate on those changes during regression testing. Collaboration and communication among the development, testing, and business teams are vital for successful regression testing. Regular meetings, clear documentation, and sharing of test results and insights help in aligning everyone involved and addressing any issues or concerns.
  • Focus on Efficient Test Design: In many cases, having a smaller number of meaningful tests can be more efficient than having a large volume of potentially redundant tests. To improve test case efficiency, it is necessary to utilize advanced test design techniques that aim to maximize test coverage while the number of tests required.
  • Establish repeatable processes: Achieving a high level of repeatability is challenging, if not impossible, without a comprehensive and consistently repeatable testing process. When performing and comparing two regression tests for the same function, it is essential to conduct them as closely as possible to ensure accurate results. While some variations may arise due to changes in new versions, the goal is to maintain consistency throughout the testing process.
  • Continuous Improvement: Regularly evaluate and refine your regression testing process. Analyze test results, collect feedback, and identify areas for improvement to enhance the efficiency and effectiveness of your regression testing efforts.
  • Continuous Integration and Continuous Testing (sometimes called Continuous Quality): Integrating regression testing into a continuous integration and continuous testing (CI/CT) pipeline ensures that tests are executed regularly and automatically whenever changes are made to the software.

The addition of automated regression to Continuous Delivery (CD) test suites can help catch application failures during the deployment stage. While it requires additional time, it proves to be beneficial. Therefore, it is necessary to prioritize and potentially have multiple test suites: a shorter one for quick feedback and a longer one for extensive coverage.

Benefits of incorporating regression testing into your software development process

  • Make future changes with confidence: Regression testing enables you to identify the specific past changes that may have impacted certain features of your software. With this knowledge, you can identify prospective problems and effectively address them, having the confidence to make future changes without the fear of unintended consequences.
  • Proactively fix issues: Regression testing allows you to identify and address issues proactively before they become major problems. By catching and resolving issues early on, you save time, effort, and costs associated with extensive bug fixing and additional development work. This proactive approach helps you maintain a stable and reliable software product. With regression testing, you can confidently adapt your software, maximize its value, and prevent potential issues, ultimately saving time and resources for your development team.

How can Regression Testing help your business?

Maintaining Quality, Stability, and Enhancing Customer Satisfaction

By conducting thorough regression testing, you can maintain the quality and stability of your software product. Regression testing ensures that your software remains stable and bug-free and contributes to overall customer satisfaction. It helps to build trust in your product and brand, as customers can rely on consistent performance and a positive user experience.

Saving Time and Costs

Identifying and fixing defects early in the development cycle is generally less time-consuming and costly than dealing with issues that are discovered later in production or by end users.

Even though it looks from first sight like you're doing the job twice, by catching and fixing issues early on, you can stop them from becoming bigger problems during production or deployment. Addressing these issues early helps you avoid delays and extra work caused by problems that show up later in the development process or after the software is released. Investment in regression testing gives your organization greater control and confidence in the quality and stability of your product.

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