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What is Regression Testing? Definition, Vantages, and Top Tools

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In the software development world, Regression Testing is a term that is heard quite often. But what does it actually mean? Regression testing is the process of testing a software product after changes have been made to ensure that no new bugs have been introduced as a result of the changes. This type of testing is critical for delivering a high-quality software product. In this blog post, we will discuss regression testing in more detail and provide an overview of some of the top tools available for regression testing.

What is Regression Testing?

Regression Testing is typically a type of software testing that is used when confirming that the most-recent program or code-related changes have not affected the existing features in an adverse manner. During regression testing, it is determined that the software or application works fine in regard to the new changes and bug fixes. Regression testing is majorly about re-executing the already executed test cases in order to confirm if the application is working appropriately.

Why do we need to perform regression testing?

There are several reasons why one should perform regression testing. The main aim of regression testing is to ensure that the application works fine when a change is made in the code. We have to test if the modified code affects the other parts of the application or not. If not, great! But if it does, changes must be made accordingly. This results in improved product quality and confirmation that the issues fixed won’t happen again. 

Some advantages of performing regression testing include:

  • Verifies that any code change does not negatively impact other features.
  • Ensure that recurring problems are not repeated.
  • During testing, it serves as a risk management technique.
  • It is simple to learn, understand, and evaluate.

What are the side effects of regression testing?

Where there are several advantages of performing regression testing, there are some disadvantages as well. 

  • Regression testing must be performed even on the smallest changes in the application to analyze the impact of the change. This can be quite frustrating sometimes. 
  • In case automation is not used in the project, it can get very tedious to execute a single test case again and again. 

Challenges when Performing Regression Testing

Regression testing helps identify bugs while adding new features or updates to an existing codebase, as well as mitigating app crashes and performance bottlenecks. When performing a Regression test, however, a tester faces several challenges.

Some of the major challenges faced by testers include:

  • Upfront Cost and Time: When new features are introduced, a regression test suite must be continuously optimized. As a result, the number of test cases varies, and existing tests must be rerun alongside new tests, which take a long time to finish. Parallel testing may be beneficial since it permits you to execute test cases in parallel across numerous browsers and operating systems, saving multiple weeks of lead time.
  • Complexity: The number of test cases and their complexity increases as the project or application grows more complicated. As a result, it takes a long time to implement and maintain.
  • Maintenance: As an application expands, the number of test cases in Regression test suites increases. As a result, maintaining the complexity and running time is critical.
  • Greater-Scope: The quality of regression testing is determined by the type of test case suite you have created. The regression suite must be updated every time there is a build or release. Now, testers would find it difficult to remember each change, and regression testing is impossible without that. That’s the only way to cover all of these elements. As a result, the enormous breadth is a significant problem.
  • Testing Approach: Selecting the best regression testing approach is critical for success. You may have access to excellent resources and tools, but if you don’t have a solid strategy in place for when and how to perform regression testing, you’ll struggle. 

Types of Regression Testing

If we want to perform regression testing, we must find the bugs in the code first. When the bugs are identified, appropriate measures are taken to fix them. After that, relevant test cases are selected from the test suite that covers both the modified and the affected parts of the code. The seven different types of regression testing include:

  • Re-test All – One way of performing regression testing is re-executing the whole test suite. This is actually an expensive process as it requires more time, resources, and efforts to re-execute the entire test suite. The failures detected in this process are reported forward to be fixed. 
  • Corrective Regression Testing – Corrective Regression testing is one of the simpler forms of Regression testing requiring minimal effort. Corrective Regression testing involves no changes to the existing codebase and adding new functionality to the application. You simply need to test the existing functionality and the test cases that go with it rather than creating new ones.
  • Unit Regression Testing – Unit Regression testing is an integral part of Regression testing in which the code is tested in isolation. All other interactions, integration, and dependencies are disabled while performing unit Regression testing, and the emphasis is on single unit code. Typically, this testing is done during low traffic and off-peak hours.
  • Selective Regression Testing – Selective Regression testing analyzes the impact of existing code and the effect of both new and existing code. Common elements like variables and functions are incorporated into the application to identify quick results without affecting the process.
  • Progressive Regression Testing – Test cases are created based on the requirements of a progressive regression test. When there are only minor product improvements, the new test cases are designed without affecting the existing code of a product.
  • Complete Regression Testing – Some minor or significant changes might have a massive impact on the product. Complete Regression testing is used in this instance when there are significant modifications to the current code. It aids in the repair of any modifications made during the testing process.
  • Partial Regression Testing – When new code is added to an existing codebase, partial Regression testing is conducted. This aids in the discovery of critical bugs in existing code and allows them to be tested without affecting the system.

How to perform Regression Testing?

Generally, there is no fixed pattern for implementing regression testing. However, there are some popular regression testing methods that a QA analyst should keep in mind.

Step 1: Regression Test Selection

Selecting here means choosing the test instances that need to be re-tested. You won’t test the entire test suite, and the list of selected tests will be influenced by the source code change in each module.

Finally, you split the test cases into two categories: Reusable Test Cases and Obsolete Test Cases. The subsequent testing cycles will not use Obsolete ones, as they are obsolete.

Below are some common characteristics of re-usable test cases:

  • Highly error-prone
  • Can verify the functionality of the application
  • Have successfully been conducted in the past
  • Failed in earlier test stages
  • Are usually related to integration and boundary-value

Step 2: Determine the Time for Executing Test Cases

Next, you must calculate how long it will take to execute the chosen test cases. The creation of test data, QA team regression testing planning, and the evaluation of all test cases are a few factors that affect execution time. 

Step 3: Identify the Test Cases that can be Automated

In this phase, the QA team can determine which test cases they may automate after analyzing the findings of exploratory testing. Automated test cases are quicker than manual testing and allow you to reuse the same script again and again. So, identify two groups of test cases: (a) manual test cases and (b) automated test cases.

Step 4: Test Cases Prioritization

Here, you combine all of the test cases and rank them. For example, high-priority test cases are those that have a far higher probability of failure. You’ll start with the high-priority tests and work your way down to low-priority ones. The priority will be determined by the product’s functionality as well as user engagement.

Below is the waterfall structure of priorities: 

  • Priority 0: The most critical test cases include all the core functionalities.
  • Priority 1: Essential features, but not a part of core functionality.
  • Priority 2: Test cases related to technical debt. 

Step 5: Executing Test Cases

Finally, it’s time to execute each test case one by one to see whether the product is performing as expected or not. You may either do manual testing or automated according to the need. Using functional tools like Selenium, QTP, Watir, and others allows you to conduct regression testing more quickly.

When to perform Regression Testing?

Regression testing is necessary after new capabilities or improvements are implemented to a current codebase or application. It ensures that any new functionality or modification to an existing application is successful and free of bugs and faults. Developers and testers frequently have trouble finding all of the code threads, with a high risk of software incompatibility problems. As a result, performing regression tests on their codebase (or application) allows them to discover flaws sooner and deliver apps with smaller risks.

When a deployment takes longer than expected, regression testing is useful. In this instance, the tester should execute Regression tests on a daily basis. It’s also preferable to conduct Regression tests after functional testing for weekly releases.

Regression testing is more important when some features are updated. Regression testing may jeopardize the present functionality of the codebase. Furthermore, correcting one problem may lead to another. In this scenario, you might use a combination of debugging and regression testing to ensure that everything performs properly.

5 Best tools for Regression Testing:

There is a tool for almost everything in today’s market. Some tools that can help you with your regression testing cycle include:

  1. Selenium – This is one of the most known and powerful tools in the market for regression testing. It offers great flexibility and compatibility with various different browsers. Also, it supports numerous programming languages, frameworks, and libraries. 
  2. IBM Rational Functional Tester – This tool is the first love for automation testers across the globe. This commercial tool supports a large variety of applications and is capable of creating different types of scenarios quickly. 
  3. Micro Focus Unified Functional Testing (UFT) – Formerly known as Quick Test Professional, UFT is one of the most popular testing tools. It is majorly known for its activity recording feature which allows the users to record their activities and further convert them into scripts. 
  4. TestSigma – This is a regression testing tool that suggests relevant and/or affected test cases after a bug fix or code change. It is an easy scriptless testing tool that lets you run the test right after the first check-in within a sprint. 
  5. Sahi Pro – This is an ideal tool for automation regression testing. It offers various features like data-driven suites, email reports, and an inbuilt Excel framework. 

Regression Vs Re-Testing

Most people misunderstand the concepts of regression testing and re-testing to be the same. That is actually not true. They are two very different concepts. 

Regression TestingRe-Testing
Regression testing is performed to analyze the effect of the new code changes on the application.Re-testing is performed when a test case fails in order to confirm that it passes in the final execution.
Defect verification is not a part of regression testing. Defect verification is a part of re-testing.
You can also do automation testing while performing regression testing as manual testing can be quite expensive and time-consuming.You can not perform automation testing while performing re-testing. 
Regression testing is executed only if either the code or the working environment is modified.Re-Testing does not have anything to do with the modifications. It executes a defect under the same code and circumstances.
Regression Testing is also known as generic testing.Re-Testing is more of planned testing. 

Regression Testing and Agile Methodology

You’ve undoubtedly heard the term “agile software development” before. The agile method, as you know, is based on incremental and iterative techniques. Sprints are short iterations that result in the production of new software or products. Many sprints equal many iterations, and a change in source code might be an addition or an upgrade with new functionality at each stage. Regression testing is where this role comes into play. 

Agile teams should create a regression test suite from the start of the product development cycle and maintain it throughout. There are two ways for conducting regression testing in agile: 

  • Sprint Level Regression: This type of regression is used to assess the influence of any new functionality added or improved in the most recent sprint. To this end, you should pick test cases based on the product’s brand-new feature.
  • End-to-End Regression: You’ll want to go through each test case and execute it again, just to make sure all basic product functions are working as expected. 

Regression testing is essential when using the agile approach since it requires rapid development iterations. Regression testing must therefore be done on a regular basis, which makes it time-consuming for QA experts. Instead of that, regression testing in an agile style is aided by automation. It allows you to save time and discover frequent flaws.

Best Practices for Regression Testers

Regression testing is the process of testing your application after it’s completed to ensure that it’s free from any bugs. However, as your application becomes more complex, the number of test cases required will increase. As a result, you’ll need a cloud-based testing solution that can expand with your testing needs.

Some best practices for regression testers include:

  • Make detailed test case situations for regression testing.
  • Keep the test case file up to date with new situations and perform regression testing on it.
  • Create a standard procedure for repeating testing on a regular basis.
  • Identify the technological or functionalities at risk because of recent upgrades or modifications.
  • After each successful compilation of the new code, perform regression testing.
  • Based on the business model for the application’s software, design the regression testing approach.
  • Compare the actual response with the expected/previous response for validity.
  • Integrate automated regression testing into your continuous integration or delivery process; this will allow you to ensure that new code modifications do not break existing functionality and that any regressions are identified and fixed as soon as possible.
  • Create a regression testing procedure and make sure everyone on the project knows about it; this will assist you and your team in adequately testing all modifications.
  • Identify the modifications or enhancements to existing modules of the application that will have an effect on its capabilities; this will assist you in focusing your regression testing efforts in those areas.
  • Ensure that the changes or upgrades haven’t harmed functionalities by using manual and automated tests; this will help you detect any regression caused by the changes or upgrades.


Change is an inevitable part of the world. It is an impossible task to avoid them. But you can ensure that the change does not affect your developed application in an adverse way. Regression testing is a way of doing that. This ensures a better quality of your product and that your product works fine even after making some changes. There are many tools in the market that can help you make your work easy. So, choose wisely, and all the best!

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