What is Regression Testing? Testing Types, Tools

Regression testing is a type of software testing that plays a crucial role in ensuring the stability and functionality of an application after changes have been made. This comprehensive testing approach includes functional testing, where test scripts are executed to verify that new code does not adversely affect existing features. The regression testing process can be carried out using both manual tests and automation tests, depending on the specific needs and resources of the testing team. Automation tools and automated testing tools significantly enhance efficiency by executing repetitive test scenarios swiftly. Visual regression testing is another critical component, focusing on identifying unintended visual changes in the user interface. A well-structured regression suite, including corrective regression testing and full regression testing, ensures that the application maintains its integrity and performance. Adopting an effective testing strategy and a robust testing approach, regression testing ensures high-quality software delivery and customer satisfaction. Let's dive into the ins and outs of regression tests.

What is Regression Testing?

Regression testing is a software testing method that aims to investigate and locate any possible flaws or bugs in software that has already been fully developed. Regression Testing is performed to find out whether your software has regressed (surprise, surprise) as you continue introducing new updates and bug fixes. Whenever a piece of software is changed in any way, new bugs might emerge and some of the older ones re-emerge.

Regression Testing Process

Regression testing is often performed immediately after introducing a new update, but it isn’t the only factor that might call for the test. If any software or hardware-related factor has changed, regression testing should be committed to find out whether everything performs as it has before the change.

This can include any sort of bug fixes and software changes, but regression might also be caused by hardware configuration changes and electronic component degradation over time. Regression testing isn’t easy – it requires cooperation and diligence out of all of the team members, which makes it perfect for agile software development practices.

Regression Testing Techniques

Regression testing is a vital process in software quality assurance, ensuring that recent changes or updates do not adversely affect existing functionalities. Here are some of the key techniques used in regression testing:

Regression Test Selection

This technique selects a subset of the test suite to execute, focusing on the parts of the application most likely affected by the recent changes.

Pros:

• Saves time and resources
• Faster feedback

Cons:

• May miss defects in non-selected areas

Best Use: Ideal for large projects with limited testing time, where specific parts of the application are more prone to regression.

Prioritization of Test Cases

Test cases are prioritized based on their criticality and the likelihood of defects in the related areas. High-priority test cases are executed first.

Pros:

• Focuses on high-risk areas
• Efficient use of testing resources

Cons:

• Lower-priority test cases might miss defects

Best Use: Effective in projects with tight deadlines, ensuring that critical functionalities are tested first.

Automated Regression Testing

Automating regression tests is highly recommended to increase efficiency and accuracy. Automated regression testing tools, such as Selenium, facilitate the execution of repetitive test cases without manual intervention, allowing for faster and more reliable test results. Automation in regression testing can be categorized into:

• Automate Regression Testing: Using automated tools to execute regression test cases.
• Test Automation: Implementing a broader strategy for automating various testing processes within the software development lifecycle.
• Automated Regression Testing Tools: Utilizing specific tools designed for automating regression tests, improving test coverage and reducing manual effort.

Hybrid Approach

Combines different regression testing techniques to leverage their strengths. For example, critical test cases are automated, while other parts of the application use test selection or prioritization.

Pros:

• Balanced approach
• Maximizes coverage with available resources

Cons:

• Requires careful planning and coordination

Best Use: Best for complex projects that require a mix of manual and automated testing, providing comprehensive coverage and efficient use of resources.

Progressive Regression Testing

This technique involves testing new features and their integration with existing functionalities to ensure that they do not introduce new defects.

Pros:

• Ensures new features are tested in context
• Identifies integration issues early

Cons:

• May require additional effort to design new test cases

Best Use: Suitable for iterative development environments where new features are added regularly.

Complete Regression Testing

Conducts thorough testing of the entire application after significant changes or at major milestones.

Pros:

• Ensures overall software integrity
• High confidence in release quality

Cons:

• Very time-consuming
• Requires extensive resources

Best Use: Typically used before major releases or after substantial code changes.

Check also our guide on Smoke Testing vs Regression Testing.

Types of Regression Testing

Regression testing can be categorized into several types, each serving a specific purpose in ensuring software stability:

1. Unit Regression Testing: Focuses on individual units or components of the software to verify that changes do not affect their functionality.
2. Partial Regression Testing: Involves testing only the modified parts of the software along with related components to ensure that recent changes have not disrupted existing functionality.
3. Complete Regression Testing: A thorough testing process that covers the entire application to ensure that recent updates or fixes have not introduced new defects anywhere in the software.
4. Selective Regression Testing: Targets specific parts of the software that are most likely affected by recent changes, optimizing the testing process by reducing scope while maintaining effectiveness.
5. Progressive Regression Testing: Applied when new test cases are created for new functionalities, ensuring that these additions do not impact existing features.

Visual Regression Testing

Visual regression testing is essential for ensuring that software updates do not unintentionally alter the user interface, preserving the consistent visual experience expected by users. It helps identify discrepancies in design elements, such as layout, color, and font changes, which might not be caught by functional tests alone. By automating visual checks, development teams can quickly pinpoint and address visual bugs, improving overall efficiency and reducing manual inspection effort. This type of testing is particularly crucial for applications where the user interface is a key component of user satisfaction and brand identity. Implementing visual regression testing as part of the regression testing process ensures a polished and professional appearance, enhancing user trust and engagement.

Check out detailed guide on the best Visual Regression Testing Tools.

When to Perform Regression Testing?

While regression testing is most commonly conducted immediately after a new update is introduced, it is not limited to this scenario. Any change in software or hardware-related factors should prompt a regression test to ensure consistent performance. This includes not only bug fixes and software modifications but also changes in hardware configurations and the natural degradation of electronic components over time.

Regression testing requires meticulous cooperation and diligence from all team members, making it well-suited for agile software development practices. Agile methodologies emphasize continuous integration and continuous delivery, where regression testing plays a vital role in maintaining software quality throughout the development lifecycle.

Learn how to set up regression testing with BugBug.

Best Practices for Regression Testing

1. Develop a Comprehensive Test Plan: Ensure you have a detailed test plan that outlines the scope, objectives, and approach for regression testing. This plan should be integrated into your overall software testing process and include both automated and manual regression testing strategies.
2. Identify and Prioritize Test Cases: Focus on identifying and prioritizing test cases for regression testing. Include high-priority functionalities and areas that are frequently modified. This helps in optimizing the testing effort and ensures that critical parts of the application are tested thoroughly.
3. Automate Regression Test Cases: Automated regression test cases are crucial for efficiency. Automation helps in reducing the time and effort required for testing, ensuring that regression tests are run consistently with each new release. Utilize tools and frameworks to automate repetitive and time-consuming test cases.
4. Maintain a Regression Test Suite: Regularly update and maintain a regression test suite to include new test cases and remove obsolete ones. This ensures that the test suite remains relevant and effective in identifying defects.
5. Use Version Control: Implement version control for your test scripts and test cases. This helps in tracking changes, maintaining consistency, and facilitating collaboration among team members.
6. Set Up Reliable Test Environments: Ensure that your test environments closely mimic the production environment. Reliable test environments are essential for accurate regression testing as they help in replicating real-world scenarios.
7. Implement Continuous Integration (CI): Integrate regression testing into your CI pipeline. This enables you to run regression tests automatically whenever code changes are made, ensuring that defects are detected early in the development cycle.
8. Focus on Effective Regression Testing: Effective regression testing verifies that recent code changes have not adversely affected existing functionality. It helps in maintaining software quality over time.
9. Test Plan for the Regression Cycle: Clearly define the regression cycle within your project timelines. This includes scheduling regular regression tests to catch defects early and ensure stability.
10. Combine Unit Testing with Regression Testing: Use unit testing to validate individual components of the software. Combining unit testing with regression testing helps in ensuring that the entire application works as expected after changes are made.
11. Adopt a Regression Testing Approach: Define a clear regression testing approach that includes methodologies, tools, and techniques to be used. This approach should align with your overall testing strategy.
12. Run Regression Tests Regularly: Regularly run regression tests to identify any unintended consequences of recent changes. This proactive approach helps in maintaining software quality and reliability.
13. Use a Test Case Template for Consistency: Utilize a standardized template for documenting regression test cases and results. This ensures consistency and helps in maintaining clear records of the testing process.
14. Test the Entire Application: While it's important to focus on critical areas, make sure to test the entire application periodically to uncover any hidden defects.
15. Monitor and Analyze Test Results: Monitor the results of regression tests and analyze the data to identify patterns and areas of frequent failure. This helps in refining the testing process and improving overall software quality.
16. Capitalize on CapEx: Leverage capital expenditures (CapEx) for investing in advanced testing tools and infrastructure. This investment can significantly enhance the efficiency and effectiveness of your regression testing efforts.
17. Engage in Manual Regression Testing: While automation is crucial, manual regression testing still plays an important role. Manual testing helps in uncovering defects that automation might miss, particularly in areas requiring human judgment and exploratory testing.
18. Implement Regression Testing Strategies: Develop and implement various regression testing strategies tailored to your project needs. This includes selective, progressive, and complete regression testing approaches.
19. Test the New and the Modified: Ensure that you test both new functionalities and any modifications made to the existing code. This comprehensive approach helps in ensuring that new changes do not introduce defects.
20. Regression Testing is One: Remember that regression testing is one of the most critical aspects of maintaining software quality. It ensures that your software remains functional and stable over time.
21. Service-Oriented Regression Testing: For service-oriented architectures, ensure that regression testing includes validating the interactions and integrations between different services. This helps in maintaining the integrity of the overall system.
22. Use Count and Non-Count Metrics: Utilize both count (e.g., number of defects found) and non-count (e.g., user satisfaction) metrics to evaluate the effectiveness of your regression testing efforts.
23. Testing Helps Maintain Quality: Overall, regression testing helps in maintaining the quality of the software by ensuring that changes do not adversely affect existing functionality.

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

Regression testing is crucial in Agile and CI/CD because it ensures that new code changes do not break existing functionality, maintaining software stability and quality. In Agile, frequent iterations and continuous delivery of new features require constant verification that previous features remain unaffected. CI/CD pipelines automate this process, enabling quick and efficient regression testing with every code integration, catching defects early. This reduces the risk of defects reaching production, ensuring a seamless user experience. Ultimately, regression testing supports the Agile principle of delivering incremental updates while maintaining a high standard of quality and reliability.

Check more about Regression Testing in Agile in our guide.

How To Build Your Regression Test Suite?

Building an effective regression test suite involves several key steps:

1. Identify Test Cases: Start by identifying test cases that cover critical functionalities of your application. This includes areas that are frequently modified, have a history of defects, or are business-critical. Focus on both positive and negative test scenarios to ensure comprehensive coverage.
2. Prioritize Test Cases: Prioritize the test cases based on their importance and impact on the application. High-priority test cases should be included in every regression cycle, while lower-priority ones can be run less frequently or only when specific modules are affected.
3. Automate Where Possible: Automate test cases that are repetitive, time-consuming, and require frequent execution. Use automation tools and frameworks that integrate well with your development environment and CI/CD pipeline. Automation increases efficiency and consistency in testing.
4. Maintain and Update the Suite: Regularly review and update your regression test suite. Add new test cases for new features and remove or modify obsolete ones. This ensures that the suite remains relevant and effective in detecting defects.
5. Organize Test Cases: Organize your test cases in a logical structure, grouping them by modules, functionalities, or other relevant criteria. This helps in managing and executing the tests efficiently.
6. Set Up Test Environments: Ensure that you have reliable and consistent test environments that mimic production settings. This includes proper configuration of databases, servers, and other dependencies to ensure accurate test results.
7. Define Clear Entry and Exit Criteria: Establish clear criteria for when regression testing should start (entry criteria) and when it can be considered complete (exit criteria). This helps in setting expectations and ensuring thorough testing.
8. Integrate with CI/CD Pipelines: Integrate your regression test suite with your CI/CD pipelines to enable automatic execution of tests with every code change. This helps in early detection of defects and ensures continuous quality.
9. Monitor and Analyze Test Results: Continuously monitor and analyze the results of your regression tests. Identify patterns, recurring issues, and areas that require improvement. Use this data to refine your test cases and improve the overall effectiveness of your regression suite.
10. Collaborate and Communicate: Ensure collaboration between development, testing, and operations teams. Regular communication helps in understanding changes, identifying potential risks, and ensuring that the regression test suite remains aligned with the project goals and requirements.

Read our guide on how to Create Test Suite and Test Cases with BugBug.

Tools for Regression Testing

Selenium

Description: Selenium is a popular open-source framework for automating web applications. It supports multiple programming languages like Java, C#, Python, and Ruby.

Key Features:

• Supports multiple browsers (Chrome, Firefox, Safari, IE).
• Can be integrated with CI/CD tools like Jenkins.
• Allows writing tests in various programming languages.
• Offers a robust set of APIs for different browsers.

Use Cases:

• Automating web application testing.
• Performing cross-browser testing.
• Regression testing of web-based applications.
• Continuous integration and delivery pipelines.

TestComplete

Description: TestComplete is an automated UI testing tool developed by SmartBear. It supports web, desktop, and mobile applications.

Key Features:

• Scripted and scriptless test creation.
• Supports a wide range of applications (web, desktop, mobile).
• Integration with CI/CD tools like Jenkins, Azure DevOps.
• Test recording and playback.
• Data-driven testing.

Use Cases:

• UI automation for web, desktop, and mobile applications.
• Regression testing of applications with frequent updates.
• Integration with continuous testing frameworks.

Katalon Studio

Description: Katalon Studio is an all-in-one test automation solution for web, API, mobile, and desktop applications.

Key Features:

• User-friendly interface with minimal coding required.
• Supports multiple platforms (web, API, mobile, desktop).
• Built-in keywords for common test actions.
• Integration with CI/CD tools like Jenkins and GitLab.
• Detailed test reports and analytics.

Use Cases:

• Regression testing for various application types.
• Functional and API testing.
• Automating end-to-end testing processes.

QTP (UFT One)

Description: Quick Test Professional (QTP), now known as Unified Functional Testing (UFT One), is a commercial automated testing tool by Micro Focus.

Key Features:

• Supports keyword-driven and scripted tests.
• Integrates with ALM/QC for test management.
• Supports a wide range of applications and protocols.
• Test recording and playback.
• Data-driven testing capabilities.

Use Cases:

• Functional and regression testing for desktop and web applications.
• Automated testing in complex enterprise environments.
• Integration with test management tools.

Appium

Description: Appium is an open-source tool for automating mobile applications. It supports both Android and iOS platforms.

Key Features:

• Supports native, hybrid, and mobile web applications.
• Cross-platform testing capabilities.
• Integration with CI/CD tools.
• Supports multiple programming languages.
• No need to modify the app for automation.

Use Cases:

• Regression testing of mobile applications.
• Automating mobile web testing.
• Cross-platform mobile application testing.

IBM Rational Functional Tester (RFT)

Description: IBM Rational Functional Tester is a commercial automated functional and regression testing tool. It supports a variety of applications including web, desktop, and mobile.

Key Features:

• ScriptAssure technology for resilient script execution.
• Data-driven testing capabilities.
• Integration with IBM's Rational Quality Manager.
• Supports multiple scripting languages (Java, VB.NET).
• Advanced reporting and logging features.

Use Cases:

• Regression testing for enterprise applications.
• Automating functional tests for diverse application types.
• Integration with IBM's software development lifecycle tools.

Read also our list of 5 best regression testing tools for web application testing.

Happy (automated) testing!

Regression Testing FAQ

What's the difference between integration testing vs regression testing?

Integration testing verifies the interactions between integrated software modules to ensure they work together correctly, typically conducted after unit testing and before system testing. It focuses on data flow and interfaces between modules. In contrast, regression testing ensures that recent code changes have not negatively impacted existing functionality, conducted throughout the software lifecycle after updates or bug fixes. While integration testing checks the combined functionality of integrated parts, regression testing revalidates the entire application or affected parts to catch new bugs introduced by recent changes.

What is the difference between sanity and regression testing?

Sanity Testing is a subset of regression testing, performed to quickly verify whether a particular function or bug fix works as intended. It focuses on validating specific functionalities after changes or fixes to ensure they are working without delving into detailed testing. Sanity tests are usually narrow and deep, checking only the critical parts of the application affected by recent changes.

Regression Testing, on the other hand, involves re-running previously conducted tests to ensure that recent code changes have not adversely affected the existing functionalities of the software. It is broader and more comprehensive, covering all major features and functions of the application to detect new bugs or issues introduced by the changes.