The Complete Guide to Regression Testing

What Is Regression Testing? Examples, Types, Tools, and Challenges

In the fast-paced world of software development, ensuring the stability and quality of applications is paramount. A small code change or a new feature addition can introduce bugs or cause existing functionalities to break. To tackle this challenge head-on, software teams employ a powerful weapon in their testing arsenal, which is regression testing.

Regression testing helps detect regression bugs, system malfunctions, and disruptions caused by recent changes in the software.

In this guide, we will explore various aspects of regression testing, including its pros, cons, examples, popular tools, challenges, and more.

What is Regression Testing ?

Regression testing is a software testing process that aims to verify that the existing features and functionalities of the software still work as expected after any code changes, bug fixes, or system enhancements. It involves retesting previously tested functionalities to ensure that they still function after changes have been made.

It involves re-executing test cases that have been previously executed to check if any defects have been introduced or if the changes made to the system have affected its stability or functionality. It helps ensure that the software system remains stable and reliable throughout the development or maintenance process.

Why Regression Testing ?

Regression testing is a critical testing practice or method that helps maintain software stability, minimize risks, and ensure that changes made to the codebase do not negatively impact existing functionalities.

It plays a vital role in delivering high-quality software that meets user expectations and business requirements.

Example of Regression Testing

Let's say a software team is working on developing an e-commerce website. After the development phase is completed, the testing team (QAs) will test the website. To do so, they will create test cases and check every aspect of the application, like speed, functionality, stability, performance, etc.

Let's say the testers create 1000 test cases to test the entire website. After the testing is done, the team releases the website to the production environment. Imagine, a few weeks later, the software team adds more features or updates to the website's codebase. Now, to ensure that the recent changes have not introduced any new bugs or caused any unintended issues, the QA team will have to perform regression testing.

To do so, they will create new test cases, let's say 100 more test cases, to test the newly introduced functionalities of the website. And it doesn't stop there. QAs will have to re-execute the previously run 1000 test cases along with the 100 new test cases to ensure the website works as intended.

Regression testing helps ensure that the recent code changes and bug fixes did not introduce regression bugs into the application. By re-testing critical functionalities, the team can maintain the quality and stability of the software throughout its development lifecycle.

Regression Testing Techniques

There are several regression testing techniques that can be applied based on the nature of the software and the changes being made. Here are some commonly used regression testing techniques,

• 1. Regression Test Selection

  • In this method, we select specific test cases from the test suite for the feature that has to be retested based on the changes made to the code.

  • The test cases are categorized as reusable and obsolete. Reusable test cases can be used again in future regression cycles, while obsolete test cases are no longer used in upcoming regression cycles.

• 2. Test Case Prioritization

  • Instead of re-testing all test cases, this technique focuses on identifying and prioritizing the most critical test cases.

• 3. Re-test All

  • This technique involves re-testing the entire set of existing test cases.

• 4. Hybrid

  • This is a combination of Regression Test Selection and Test Case Prioritization methods. That is, instead of selecting the entire test suite, we only select the test cases that are re-executed based on their priority.

• 5. Corrective Regression Testing

  • It helps ensure the existing code works correctly and checks if the current test cases are usable. When the test results turn positive, QAs can be confident that the test cases are effective and up-to-date. It also allows QA to proceed with test planning and prioritization while incorporating new code changes into the testing process.

• 6. Progressive Regression Testing

  • It is a testing approach where QAs recognize that code changes may require changes to the test suites. So, they will work on updating the test scripts to align with the new requirements. This method is used when a change affects the product vision.

• 7. Selective Regression Testing

  • Selective regression testing is performed to observe how the code behaves when new code is added to the program. Here, a subset of test cases is selected based on the impacted areas of the software that have been modified.

• 8. Partial Regression Testing

  • Partial regression testing helps identify issues that may arise when newly written code is integrated into existing code. It ensures that the application's performance has not been impacted because of new code.

Learn more about the types of regression testing.

Selecting Test Cases For Regression Testing

Selecting the right test cases for regression testing can be a challenging task that requires skill and expertise. You can select the regression test cases based on the below criteria,

• Test cases that have frequent defects

• Test cases that validate the core product features

• Functionalities that are more visible to the end-users

• Test cases related to the product functionalities that underwent more frequent changes

• All complex test cases

• All integration test cases

• Boundary value test cases

• Sample of both successful and failed test cases

Why is Regression Testing Important in Agile and CI/CD?

CI/CD involves a series of automated tests that enable continuous testing while continuously pushing or integrating new code. This approach allows for frequent releases, resulting in faster feedback loops and avoiding the chance of broken code near the production date.

Even small changes in the software can have a big impact on its key functions. Regression testing helps align with the Agile testing methodology, here and tests for the impact of the new code.

Also, regression testing goes beyond just checking the core product functionality. It can also involve analyzing the software for optimization and improving the user experience (UX). For example, it can identify defects and suggest ways to enhance the UX.

Besides functional testing, visual regression testing helps detect even the slightest UI bugs that may occur due to code changes. For example, it helps identify issues such as non-clickable buttons, alignment issues, font size issues, and more.

Rather than manually reviewing each UI element across various devices and browsers, automated regression testing can quickly locate these visual bugs.

Simply put, regression testing helps maintain the integrity and reliability of the software throughout the development process. It ensures that the existing functionalities remain intact, bugs are caught early, and the software is continuously deployable, supporting the rapid delivery of high-quality software.

Regression Testing and Configuration Management

Configuration management is crucial during regression testing in Agile environments, where code is continuously modified. To ensure your regression tests are effective, follow the below guidelines,

• The code that is being tested must be managed by a configuration management tool. It helps ensure proper version control and helps maintain a record of changes made.

• Avoid making any changes to the code during the regression test phase. It helps maintain the integrity of the tests.

• Isolate the database used for regression testing. It helps ensure consistent and reliable test results.

Disadvantages Of Regression Testing

While regression testing offers several advantages, it also has some potential disadvantages, like,

• Regression testing has to be done even for small code changes, as they might affect the existing functionality.

• It is time-consuming and resource-intensive, especially when executed manually. Running many test cases, particularly in complex systems, can increase the required effort and time.

• The regression test suite must be constantly updated and maintained as the software evolves and new features are added.

• It can be challenging to achieve complete test coverage in regression testing, especially when changes affect a wide range of functionalities or modules.

• While regression testing helps identify regressions, it does not guarantee the absence of all defects.

• Over time, as the software evolves and new test cases are added, there may be redundancy in the test suite.

Challenges in Regression Testing

The challenges in regression testing are as follows,

• As regression testing progresses, test suites tend to grow in size. However, due to limitations in time and budget, it becomes difficult to execute the entire test suite.

• Determining the frequency of regression tests, such as after every modification, build update, or bug fix, poses a challenge and requires careful planning.

• Finding a balance between minimizing the test suite while ensuring maximum test coverage is a challenge.

Top Regression Testing Tools

There are several regression testing tools available in the market, each with its own set of features and capabilities. Here are some of the top regression testing tools widely used in the industry,

• 1. Testsigma

  Testsigma is a powerful AI-driven cloud-based test automation tool that you can use for regression testing. It is a one-stop solution for testing your web, desktop, and mobile apps and APIs from the same place.

  

  Let's take a look at the top benefits it offers to end-users,

  • It supports both code-based and codeless test automation, allowing testers to create regression test cases without the need for coding. This makes it a perfect tool for both technical and non-technical users.

  • It supports NLPs, which allows testers to write test cases and test steps in plain English language.

  • With Testsigma, regression tests can be executed on various browsers and platforms. It supports over 3000+ real devices/tablets and 1000+ browser/OS combos.

  • It includes in-built test review management and self-healing capabilities.

  • It supports CI/CD workflows with third-party applications like Jenkins, Slack, Jira, etc.

  • It supports parallel testing across different test environments.

  • It is available as both open-source and Enterprise ready.

  • It supports Java allowing users to write test scripts for certain scenarios that might require code.

  • Users can record user interactions and automate them as test cases on the cloud using the Record feature.

  • It offers 24x7 extended customer support to users via email, chat, community, and phone.

  • You have the freedom to create custom NLPs and make them either public or private to your organization.

  Testsigma's pro version, the Testsigma Cloud, is available to use for free as it offers a 21-day free trial where you can benefit from all the features. Also, it offers various pricing plans to cater to different business needs and requirements. It offers a forever free plan where testers can run automated tests for free, but mostly suitable only for small projects. Further, the Testsigma Enterprise plan is specially designed for larger organizations with complex testing needs and demands.

Automate your regression tests for web, mobile, desktop applications and APIs, 5x faster, with Testsigma

Try Testsigma

• 2. Selenium

  Selenium is a widely used open-source framework for automating tests on web browsers and supports regression testing of the same too.

  
  • You can create test scripts in various programming languages like Java, Javascript, PHP, Perl, Ruby, C#, and Python.

  • It supports different browsers like Chrome, Firefox, Safari, Edge, and Internet Explorer.

  • It supports different platforms like Mac, Windows, and Linux.

  • It allows parallel test execution.

  • Selenium can be integrated with test frameworks, such as TestNG, JUnit, or NUnit.

  While Selenium is a powerful tool for regression testing, it is essential to note that it supports only web-based testing. So, you should use other tools like Testsigma for desktop or mobile app testing.

• 3. Katalon Studio

  Katalon Studio is another popular test automation tool that you can use for regression testing.

  
  • Katalon supports programming languages, including Groovy and Java.

  • It offers integrations with various applications like Git, Jenkins, and JIRA.

  • It supports various platforms, browsers, and devices.

  • It easily integrates into your CI/CD pipeline.

  • It supports record-and-playback feature to record user actions as test cases.

• 4. Apache JMeter

  Apache JMeter is another top open-source automated regression testing tool mainly used for performance testing, load testing, stress testing, and functional testing of web applications. JMeter is written entirely in Java programming language. It supports different platforms like Linux, Windows, and Mac.

  

Automated Regression Testing Using Testsigma

Let's consider you are working on a website, and a new feature has been added to the login functionality. You want to ensure that this new feature does not introduce any regressions or impact the existing functionalities of the website.

Web Application URL - https://id.testsigma.com/ui/login

Regression Test Scenario - Consider that the login functionality of the application with email/password is tested successfully. Now, the software team has added a new functionality, "Forgot Password."

Now, QAs should test the new functionality along with the old test cases to ensure the overall login functionality works.

That is, if I had written 5 automation test cases to test Sign-in functionality, now I would create 4 more new test cases to test the Forgot Password and then the sign-in. And I would run the new test cases along with the old test cases to test the entire functionality.

Follow the below steps to test the Forgot Password feature along with the application's overall login functionality in Testsigma.

Note - Below image depicts the previously run test cases for testing the login functionality of the application. Now, we will add or update the test cases to test the overall login functionality of the application along with Forgot password.

Step 1 - Create a new test case using the Create button.

Step 2 - Now, start creating test cases using the NLPs. Also, you can easily record the elements from the webpage using the Record Element.

Note - Refer to the below gif to know better on how to use Record Element to create test cases.

Step 3 - Add the new test cases along with the old test cases. Here, I have created the new test cases for Forgot Password as follows,

Step 4 - Click on Run to execute the regression test cases.

Step 5 After the test is successful, you can analyze the test results in detail using the logs, screenshots, and video.

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Retesting vs Regression Testing

Retesting and regression testing are two distinct testing activities that serve different purposes in the software testing process.

Here is a detailed comparison between re-testing and regression testing,

Summary

Regression testing plays a vital role in the software development lifecycle, helping to ensure that changes to the software do not introduce unexpected regressions or break existing functionalities.

By embracing regression testing and leveraging automation testing tools, software teams can deliver high-quality software that meets user expectations and withstands the evolving demands of the market.