What is regression testing?

Regression testing is a process that ensures that software still performs as expected, even after a change.

A regression is a specific type of bug or issue that occurs when new code changes, like software enhancements, patches, or configuration changes, introduce unintended side effects or break existing functionality that was working correctly before. This can happen when new code conflicts with existing code. Regression testing helps identify and fix these bugs and issues so that the reliability of the software and the quality of the product can be maintained.

Understanding regression testing

Some software development teams may skip regular regression tests, instead relying on one-time checks for essential functions. This approach may seem efficient, but it often misses unexpected issues that can arise from small code changes. Regression testing is crucial because even minor alterations can unexpectedly impact seemingly unrelated functions in a program.

Regression testing ensures that modifications not only behave as intended but also avoid unintended consequences in previously functional areas. Building a robust regression test suite from existing functional, unit, integration, and build verification tests developed throughout a project can help engineers catch unforeseen issues, and automated testing tools can help them efficiently execute these tests, even on complex projects with thousands of test cases. Using regression testing to retest relevant components after each source code modification is crucial for ensuring ongoing software stability.

Why is regression testing important?

Regression testing plays a pivotal role in the software development process for several reasons:

• Detecting regressions: Regression testing helps identify unintentional changes in the software that affect functionality.

• Ensuring software stability: By retesting the unchanged parts of the software, regression testing ensures that the existing functionalities are still working as expected.

• Facilitating continuous integration: In a CI/CD environment, where code changes are frequent and deployments rapid, regression testing plays a critical role in ensuring new features and fixes don't unintentionally break existing functionality, enabling confident and reliable releases.

• Increasing productivity: Coupled with developer productivity resources like GitHub Copilot, efficient regression testing can help fix problems faster, accelerating the pace of software development.

• Preventing unintended consequences: Regression testing goes beyond catching bugs and regressions; it also helps unearth unforeseen consequences and side effects introduced by modifications, like security and compatibility issues. This allows for early detection and mitigation of issues before they become potential complications.

• Maintaining user confidence: Consistent software behavior builds user confidence, and regression testing helps maintain this consistency.

• Supporting agile development: In agile development, where changes are frequent, regression testing ensures that these changes don't negatively impact the software.

• Reducing debugging costs: Early detection of bugs through regression testing can significantly reduce the cost of debugging.

How to perform regression testing

Software testers, and sometimes developers, perform regression testing. This step-by-step guide shows how to perform regression testing:

1. Identify test cases: Identify the test cases that need to be executed. These could be functional, integration, or system tests that have been executed previously.

2. Execute test cases: Run the selected test cases. This can be done manually or using automated testing tools, depending on the complexity of the test cases and the resources available.

3. Analyze test results: Once the test cases have been executed, the results need to be analyzed to identify any failures or discrepancies.

4. Fix failures: If any test case fails, the issue needs to be fixed. This could involve debugging the code, making necessary changes, and retesting.

5. Document results: Finally, document the results of the regression testing. This includes the test cases executed, their results, any issues identified and fixed, and any observations or recommendations for future testing.

Automating Regression Testing with CI/CD Tools

CI/CD tools offer a seamless way to automate regression testing, making it more efficient and effective.

CI/CD tools allow developers to integrate their changes into a shared repository several times a day. Each integration is then automatically tested, which includes regression tests, to detect problems early. If a test fails, the CI/CD pipeline breaks, and developers are alerted to fix the issue immediately. This ensures that the software is always in a releasable state.

Automating regression testing with CI/CD tools not only saves time but also ensures consistency and accuracy during the enterprise application development process. It eliminates the risk of human error and allows for more frequent testing, leading to early detection of bugs and regressions.

GitHub is one popular platform that offers a native CI/CD tool called GitHub Actions. Actions provides robust features for automating regression testing within its CI/CD environment. By utilizing these tools, teams can set up automated regression testing workflows that run whenever code is pushed to the repository, ensuring that any regressions are caught and addressed promptly.

Types of regression testing techniques

Regression testing is a critical part of the software development lifecycle (SDLC), and it comes in various forms, each serving a specific purpose. For example:

• Unit regression testing: Retesting a specific unit of code (like a function or method) after modifications have been made to ensure it still works as expected.

• Partial regression testing: Testing certain parts of the system that have been changed, along with any directly related components.

• Complete regression testing: Retesting the entire system. This is typically more time-consuming and is often used when a significant change has been made to the system.

• Progressive regression testing: Testing new features while ensuring that old features still work as expected.

• Selective regression testing: Selecting specific test cases from the test suite that are likely to be affected by the change, rather than running the entire test suite.

• Automated regression testing: Using automated testing tools to run regression tests, which can save time and resources, especially for large systems.

• Manual regression testing: Manually running the regression tests. This testing can be more time-consuming but is sometimes necessary for complex scenarios that require human judgment.

• Non-functional regression testing: Testing non-functional aspects of the system like performance and usability after changes have been made.

Regression testing vs. smoke testing

Regression testing and smoke testing are two distinct types of software testing, each serving a unique purpose in the SDLC.

Developers and software testers perform regression testing to ensure that software which has been developed and tested can still meet performance expectations after modifications or changes. It involves re-running functional and non-functional tests to ensure that the existing functionalities have not been affected by the recent changes.

On the other hand, smoke testing is a high-level type of software testing where the most crucial functions of a program are tested to ensure they work correctly. It is usually performed to determine if the most important software application is working properly.

While regression testing is about ensuring that changes don't break existing functionality, smoke testing focuses on verifying that the critical functionalities of a system are working as expected.

Regression testing vs. unit testing

While both regression testing and unit testing are important aspects of the software development process, they differ in their scope and purpose.

While regression testing focuses on unintended side effects resulting from changes, unit testing focuses on validating individual units or components of a software application in isolation. Conducted during the coding phase by developers, unit tests ensure the correctness of functions, methods, or classes. These tests are isolated and typically involve checking input, output, and internal logic. Unit testing helps catch errors at the smallest level, providing confidence in the behavior of individual code units.

Best practices for regression testing

Here are some best practices to follow when performing regression testing:

• Maintain an organized test suite: Keep your test cases structured and categorized to facilitate easy navigation and updates.

• Prioritize test cases: Rank test cases based on risk and importance. High-risk areas should be tested first.

• Automate repetitive tests: Automation can save time and resources, especially for repetitive regression tests.

• Incorporate testing into your CI/CD pipeline: Integrate regression testing into your continuous integration/continuous deployment pipeline to catch issues early.

• Use version control: Use version control systems to facilitate collaboration and track changes.

• Collaborate with developers: Foster a collaborative DevOps environment between testers and developers to ensure comprehensive coverage.

• Practice effective defect tracking and reporting: Use a robust defect tracking system to document, track, and resolve issues.

• Conduct thorough test case reviews: Regularly review and update test cases to ensure they remain relevant.

• Monitor regression testing metrics: Track key metrics to assess the effectiveness of your regression testing.

• Use exploratory testing: For complex scenarios, exploratory testing can uncover issues missed by automated tests.

• Partner with experts: Work with trusted organizations that prioritize security, compliance, and transparency in all facets of the software development process. Explore the GitHub Copilot Trust Center to learn more.

Challenges and considerations for regression testing

Regression testing, while crucial, presents several challenges:

• Time consumption: Regression testing can be time-consuming, especially for large systems.

• Resources needed: It requires significant resources, both in terms of personnel and infrastructure.

• Selecting the right test cases: Identifying the most effective test cases to include in the regression suite can be difficult.

• Balancing cost and coverage: Striking a balance between the cost of testing and the need for comprehensive coverage is challenging.

• Integrating with CI/CD pipelines: Incorporating regression testing into CI/CD pipelines requires careful planning and coordination.

• Managing test data: Ensuring the availability of appropriate and up-to-date test data is often a hurdle.

• Safeguarding security: Vulnerabilities can derail progress. Adopt effective security measures like using GitHub security tools, designed to find and fix vulnerabilities to help secure the supply chain.

Addressing these challenges during the development of an enterprise application is key to ensuring the effectiveness of regression testing efforts. Team members can create review processes that improve code quality and fit neatly into workflows with resources like GitHub code review tools.

Align regression tests with the SDLC

Aligning regression tests with the software development life cycle (SLDC) is crucial for preventing regressions, maintaining software stability, and delivering high-quality products. It ensures that any modifications, enhancements, or bug fixes in the software do not inadvertently introduce new errors or re-introduce previously fixed errors.

As part of the SDLC process, application security testing (AST) ensures that applications are more resilient to security threats. AST helps identify weaknesses and vulnerabilities in source code. Furthermore, dynamic application security testing (DAST)is an application security program. DAST assists developers during the SDLC by helping them catch vulnerabilities caused by malicious attacks.

GitHub offers a range of products and solutions that support this alignment. For instance, GitHub Actions allows you to automate your regression tests and integrate them into your CI/CD pipeline. This ensures that regression tests are run consistently, and results are reported in real time, enabling teams to maintain high software quality throughout the SDLC.