What is Regression Testing? Definition, Tools, Best Practices, and More

Regression testing is a type of software testing that checks and validates that recent changes, such as bug fixes, enhancements, or configuration changes, have not negatively impacted the existing functionality of the software. It is used to achieve the required software quality characteristics in the software product.

When a new feature is added or a bug is fixed, there’s always a risk that the change may introduce new issues or break existing functionality. Regression testing mitigates this risk by re-executing previously completed test cases, comparing the outcomes with the expected results, and confirming that the software behaves as intended.

However, regression testing is not a one-off activity but rather an ongoing process in the software development lifecycle. Every time the codebase is modified, a new round of regression testing is conducted to confirm that everything still functions as expected. The frequency and scope of regression testing depend on the project’s nature, with complex projects requiring extensive and frequent testing.

Also Read: Different Types of Software Testing

Why is Regression Testing Important?

Regression testing is important because it validates that software changes do not disrupt existing functionality. Software evolves through updates and modifications and each change introduces a risk of unintentionally breaking previously working components. Without regression testing, these risks can lead to critical issues in the production environment. As a key process that safeguards the stability and reliability of the software throughout its lifecycle, regression testing:

Protects the Software Against Unintended Consequences: Every code change, no matter how small, has the potential to impact other parts of the software. Regression testing helps identify these unintended consequences early, before they escalate into major issues.
Maintains Software Stability: Stability is a key factor in user satisfaction. Regression testing helps maintain application stability by preventing new changes from introducing instability in the application.
Supports Continuous Integration and Deployment: In software development practices like Continuous Integration (CI) and Continuous Deployment (CD), regression testing plays a vital role. As it keeps frequent code changes from introducing new defects, it allows teams to confidently deploy updates.
Saves Time and Resources: Catching issues early in the development process is far more cost-effective than fixing them after the software has been released, which is made possible by regression testing as it identifies issues before they reach the production stage.

Benefits of Regression Testing

Following are the important benefits of regression testing:

Early defect detection
Improved Software Stability
Enhanced Confidence in the codebase
Cost efficiency
Continuous Integration

We discuss them in detail below:

1. Early Detection of Defects

By regularly re-testing existing functionality, regression testing helps identify issues that might have been introduced by recent changes before they become critical.

2. Improved Software Stability

Regression testing helps maintain the stability by ensuring that the software continues to function correctly after each change. Maintaining the stability of the software is crucial, especially as new features are added or existing features are updated.

3. Enhanced Confidence in the Codebase

Knowing that the software has undergone thorough regression testing gives developers and stakeholders confidence that the recent changes have not introduced new issues. Being confident about your database is important especially in large-scale projects with complex codebases, where the risk of introducing defects is higher.

4. Cost Efficiency

Regression testing helps reduce the overall cost of development by identifying and fixing issues before they reach the production stage. In any case, catching defects early in the development process is far more cost-effective than addressing them later.

5. Supports Continuous Integration

In modern software development practices like Continuous Integration (CI), regression testing is an essential component. Regression testing performs the important task of non-introduction of new defects when the code undergoes changes, and code update process can be carried out uninterruptedly.

Challenges in Regression Testing

Despite its many benefits, regression testing also presents several challenges such as:

Time Requirement
Resource Requirement
Test Maintenance Complexity
Risk of Missing Critical Defects
False Positives and Negatives

These challenges can make it difficult to implement regression testing effectively. Let’s explore them in detail, below:

1. Time-Consuming Nature

Regression testing can be extremely time-consuming, especially in large projects with complex codebases. Running a comprehensive regression test suite can take hours or even days, depending on the size and complexity of the software. By incorporating automated testing tools and parallel test execution, you can significantly speed up the process and get faster feedback on changes, allowing for more efficient use of testing time.

2. Resource-Intensive Process

Regression testing requires significant resources, including time, personnel, and infrastructure. Automated regression testing tools can help mitigate this, but they also require significant upfront investment in terms of time and resources to set up and maintain. The solution lies in leveraging cloud-based testing platforms or pre-built automation frameworks. Through this approach, organizations can optimize resource usage and reduce the need for heavy infrastructure, thereby balancing both costs and efficiency.

3. Difficulty in Test Case Maintenance

As the software evolves, test cases need to be updated to reflect the changes. Maintaining a large and complex test suite is a tough task, especially as the software grows and changes over time. Test cases that are not regularly updated can become obsolete and lead to inaccurate test results. odular and reusable test case designs, along with continuous integration practices offer an answer here. They can streamline the maintenance process, ensuring that tests remain relevant and easy to update as the software evolves.

4. Risk of Missing Critical Defects

Even with a comprehensive regression test suite, there is always a risk of missing critical defects. This can happen if the test cases do not cover all possible scenarios or if the tests are not executed correctly. The complexity of modern software makes it difficult to achieve 100% test coverage, which means that some defects may go undetected. To mitigate the risk, implementing risk-based testing and continuously reviewing and updating test cases to reflect new features or changes increases coverage and helps identify critical defects early.

5. False Positives and Negatives

A false positive occurs when a test case fails even though the software is functioning correctly, while a false negative occurs when a test case passes even though the software has a defect. When encountered, these issues result in waste of time and effort as testers investigate non-existent problems or miss real issues. Here, it is essential to regularly review and fine-tune test scripts, using techniques such as mutation testing or advanced debugging tools, to minimize errors in test results and increase the accuracy of the testing process.

Regression Testing Tools and Frameworks

Several tools and frameworks such as Selenium, JUnit, Apache JMeter, Jenkins, and Appium etc. have been developed to streamline the regression testing process. Each tool has its strengths and is suited to different types of projects or testing environments. The choice of tool often depends on the specific needs of the project, such as the programming language used, the complexity of the application, and the need for automation. We look at some of the commonly used tools in regression testing.

1. Selenium

It is one of the most-used automated testing tools in regression testing and is also one of the essential tools for Java development. Since it supports multiple browsers and operating systems, it is a versatile choice for regression testing. Selenium WebDriver allows testers to write test scripts in several programming languages, including Java, C#, and Python, which work on different browsers.

2. JUnit and TestNG

These are testing frameworks primarily used for unit testing in Java. They are also used for regression testing, particularly in projects where unit tests are part of the regression test suite. JUnit is simple and effective for small to medium-sized projects, while TestNG provides more advanced features, such as parallel execution, which is useful in large projects.

3. Apache JMeter

Apache JMeter is a performance testing tool that is used for regression testing. Especially suited to applications that need to handle high loads, it allows testers to simulate a heavy load on a server, group of servers, or network, to test its strength and analyze overall performance under different load types.

4. QTP/UFT (Quick Test Professional/Unified Functional Testing)

QTP, now known as UFT, is a commercial tool developed by Micro Focus for automated functional and regression testing. It supports a wide range of applications, including web, desktop, and mobile applications. UFT provides a sophisticated IDE that integrates with other testing tools, making it suitable for large-scale regression testing.

5. Cypress

A newer tool that is rapidly gaining popularity for end-to-end testing of web applications, Cypress is known for its ease of use, especially when testing modern JavaScript frameworks like React and Angular. It offers automatic waiting and eliminates the need for manual waits and timeouts, something that makes it a reliable choice for regression testing.

6. Jenkins

Jenkins is a continuous integration tool that helps automate the regression testing process. It integrates with various testing tools like Selenium, JUnit, and others to trigger regression tests automatically whenever code changes are pushed to the repository. Using Jenkins, teams can set up pipelines that run regression tests automatically, and provide immediate feedback on the health of the codebase.

7. IBM Rational Functional Tester (RFT)

IBM RFT is another commercial tool that supports automated regression testing. Offering features like data-driven testing, it is designed for testing complex applications, and supports a wide range of applications, including web, desktop, and mobile.

8. Appium

Appium is an open-source tool for automating mobile applications. It supports both Android and iOS platforms. Using Appium, testers are able to perform regression testing on mobile apps to confirm that new changes have not impacted existing functionality.

How to Perform Regression Testing: Examining the Workflow

The workflow for conducting regression testing can be broken down into several key steps, which we see below:

1. Identification of the Scope of Testing

Before starting the regression testing process, it is important to determine the scope of testing. Not every part of the application needs to be tested; only those areas that are affected by the recent changes should be included in the regression test suite. Testers should conduct impact analysis to identify which modules or components of the software are most likely to be affected by the changes, and proceed accordingly.

2. Update Test Cases

Requisite test cases from previous testing cycles will need to be updated to reflect the recent changes in the code. If new features have been added, new test cases must be created. If existing functionality has been modified, the corresponding test cases must be updated to reflect these modifications.

3. Prioritize Test Cases

Not all test cases are of equal importance. Some are critical for the core functionality of the software, while others are less critical. Prioritize test cases by focusing on the most important ones first, so that the core functionality is thoroughly tested before moving on to less critical areas.

4. Test Execution

Once the regression test cases are prepared and prioritized, the next step is to execute them. Depending on the project’s needs, this can be done manually or through automated tools. Automated testing is preferred for regression testing, as it allows for faster and more reliable test execution, especially in large and complex projects.

5. Analyze Results

After the tests have been executed, the results need to be analyzed to identify any issues or bugs. Test results should be thoroughly reviewed, and any discrepancies should be investigated to determine whether they are due to issues in the software or in the test cases themselves.

6. Reporting and Documentation

Finally, all findings from the regression testing process should be documented and reported to the relevant stakeholders. The report should include details on which test cases were executed, what issues were found, and recommendations for addressing these issues. Documentation serves as a knowledge reference for future regression testing cycles, as it helps in tracking the history of testing and understanding the evolution of the software.

Types of Regression Testing

The 6 main types of regression testing are:

Corrective Regression Testing
Progressive Regression Testing
Retest-all Regression Testing
Selective Regression Testing
Partial Regression Testing
Complete Regression Testing

Regression testing can be classified into several types, each suited to different testing scenarios and project needs, as we discuss.

1. Corrective Regression Testing

Corrective regression testing is performed when no changes are made to the existing codebase. It focuses on testing the existing functionality to confirm that it remains unaffected and is used when the code is stable, and the development team is confident that no major changes have been introduced.

2. Progressive Regression Testing

It is used when changes are made to the codebase, such as when new features are added or existing ones are updated. It is more comprehensive than corrective regression testing, as it covers both the new changes and the existing functionality.

3. Retest-All Regression Testing

As the name suggests, retest-all regression testing ensures that the entire application is retested after a change has been made. The significance of this regression test procedure lies in the fact that even a small change can affect the application functionality and so it is important to test all features again. Due to its “test-everything-again” nature, it is the most time-consuming and resource-intensive type of regression testing, but on the flip-side a test that provides the most comprehensive coverage.

4. Selective Regression Testing

It focuses on testing only the parts of the application that are most likely to be affected by recent changes. A condition that goes with this test is that the development team must have a good understanding of the impact of the changes and can accurately identify which areas of the software need to be tested.

5. Partial Regression Testing

Partial regression testing is similar to selective regression testing but the only difference is that it focuses on testing a smaller subset of the application. It is used when the changes are limited to a specific module or component of the software, and the development team is confident that the impact of the changes will be minimal.

6. Complete Regression Testing

In complete regression testing, all the functional and non-functional dimensions of the application are tested again. As against the retest-all approach, here testing extends to performance, compatibility, and security. This regression testing methodology is used when major changes have been made to the codebase and checking all aspects becomes essential.

What are Important Regression Testing Techniques to Follow

These are the key techniques that expert QA professionals implement when conducting regression testing so as to derive effective outcomes:

Retest All: Retest the entire application after changes have been made, so that there is no scope for defects at all.
Select Required Test Cases: Instead of retesting everything, test only the parts of the application that are most likely affected by the recent changes. Here, test cases are categorized into reusable (for future regression cycles) and obsolete (no longer needed).
Prioritize Test Cases: In this method, test cases are prioritized based on their importance, impact on the application, and the likelihood of finding defects. High-priority tests are executed first to catch critical issues early.
Adopt a Hybrid Approach: It is a testing approach that combines regression test selection and test case prioritization. It selectively retests the application while prioritizing test cases to optimize both coverage and efficiency.

What are The Best Practices to Follow in Regression Testing

Following are the best practices that must be considered and applied to implementing regression testing. They will allow you to get the most out of the testing process and effectively keep defects at bay.

1. Prioritize Test Cases

Not all test cases are equally important, so prioritize test cases that concern the most critical parts of the application. Test them first and reduce the risk of critical defects slipping through the cracks.

2. Automate Where Possible

Automating regression testing saves time and resources. Identify all opportunities for automation, so that you save time on testing. Automated tests can be executed quickly and consistently, and provide immediate feedback on the health of the codebase.

3. Regularly Update Test Cases

Test cases should be regularly updated to reflect changes in the software, which means that new test cases are added for new features, existing test cases are updated to reflect changes in functionality, and obsolete test cases are done away with.

4. Maintain a Comprehensive Test Suite

A comprehensive regression test suite should cover all critical areas of the application, including edge cases and boundary conditions. Through the approach all possible scenarios are tested and defects are caught early in the development process.

5. Perform Regression Testing Early and Often

Regression testing should be performed early and often in the development process, which is important to catch defects before they become critical.

Example of Regression Testing

For financial businesses, a portfolio management system processes different investment types, including stocks, bonds, mutual funds, and alternative assets. Additionally, it offers features like real-time portfolio tracking, performance analysis, risk assessment, and client reporting.

Now, regression testing comes into picture when new functionalities, such as risk modeling algorithms or client reporting templates, are added to the system. An update might introduce a bug in the calculation logic; without regression testing, this error could go unnoticed and reports will be incorrect. In any case, the inaccuracy will invite penalties.

Additionally, since the system integrates with real-time market data feeds, trading platforms, CRMs, and accounting systems, it means that even minor updates can have far-reaching consequences.

In another scenario, regression testing will detect that a change in the API interaction with the trading platform unintentionally disrupted trade order execution, which could otherwise lead to missed trading opportunities or financial losses. By identifying and rectifying such issues early, regression testing prevents operational disruptions and saves costs.

Conclusion

The application of regression testing may be the difference between a software product that functions seamlessly and one riddled with issues, which makes it the task of experts.

Finoit’s professional software development services offer the required expertise and experience in software quality assurance needed to execute regression testing effectively.

We prioritize critical test cases, apply automation at the right places, and perform regression testing early and often. By following this approach, our teams identify and fix issues before they reach the production stage, thereby contributing to the overall success and stability of the software.