Introduction
Software is continuously evolving. Each time a new version is published, a new feature is introduced, or a bug is fixed, something that worked perfectly fine before becomes affected.
This is why teams depend on regression testing, a practice that allows developers to achieve software stability despite continuous changes.
Let’s explore what regression testing is in software, why it’s important, and how it fits into the software development process.
What is Regression Testing in Software?
Regression testing is the act of re-running existing test cases in the software to confirm that recent changes to the code have not broken any existing functionality.
In other terms, regression testing checks that the way the system operated before remains the same after any code has changed anytime there was an update, fix, or “improvement” introduced. The term used in software development for either a feature or functionality that once worked but now fails is called a ‘regression’.
The primary purpose of regression testing is to maintain the stability of software as it goes through the development lifecycle. When developers change the code, even changing or altering one small thing in the code could lead to multi-level ripple effects down the line in other areas. Regression testing determines if those effects were achieved before it gets to the end users.
For example, if the new payment feature causes the login to fail, regression testing would indicate that.
What is regression testing in software development?
Regression testing is the process of validating that software changes do not introduce new faults. It is a statement of commitment to code quality across releases. It is also a means for teams to build trust in their deployment process.
The meaning here includes much more than just identifying faults. Regression testing represents that due diligence is exercised in the approach to software development. It represents collective ownership by the team of stable experiences for the users of the software product.
Why does regression testing matter?
When you change software, even a small change can cause big problems. Regression testing confirms that the new changes do not degrade the experience of something that was working today.
It is an assurance of product stability, as well as an assurance of risk and quality of the software.
Users expect their applications to work consistently with every update. Regression testing helps maintain this consistency by validating existing functionality. Maintaining a consistent and expected user experience builds user confidence and protects the brand reputation.
When should Regression testing be performed?
You should perform regression testing every time you make changes to the code that can affect the behavior of the system.
New features, user interface changes, bug fixes, or changes to integrations are all code changes that require regression testing.
In an Agile, continuous integration and continuous delivery (CI/CD) regression testing is performed frequently, many times automatically after each build.
The Regression Testing Process
Below is a typical regression testing process:
- Identify the areas of your application that are affected by the new changes.
- Select the relevant test cases from the test suite.
- Execute your tests using either manual regression testing or automated testing tools.
- Compare your test results against the previous baseline you have identified.
- Fix the issues and rerun your tests to validate continued stability of code.
Continue the process until your application behaves as expected.
Types of Regression Testing
There are multiple types of regression testing, each with a specific purpose:
1. Unit Regression Testing
This type tests one module after it has been changed. Developers use regular unit regression testing to verify the correct execution of small units of code.
2. Partial Regression Testing
Partial regression testing focuses on only the modules directly impacted by the latest code changes.
3. Complete Regression Testing
When there have been major code changes, you will run the full test suite, called complete regression testing, to validate the full application works.
4. Selective Regression Testing
To avoid full application testing, selective regression testing runs only selected test cases that relate to the issue that was addressed.
5. Progressive Regression Testing
Validating both old functionality and newly added functionality to validate any new code when new features are added is called progressive regression testing.
Each type of testing will strategically help manage time based on the size of the project and determination of urgency and manageability of functionality regression testing.
6 Best Practices for Regression Testing
To ensure a smooth and efficient regression testing process, it is important to adhere to these best practices:
- Ensure that test cases are simple and modular.
- Prioritize all the test cases so that you can run high-risk tests first.
- Maintain stable environments to ensure consistent test results.
- Integrate regression testing early in your development process.
- Leverage existing test cases when applicable.
- Use a combination of manual testing and automation testing for better coverage.
Applying these best practices for regression testing will result in more reliable applications.
How to Execute Efficient Regression Testing?
Performing efficient regression testing is very time- and money-saving for a company. Following are the ways to execute regression testing.
1. Efficient test execution always executes critical test cases first. This means it detects major issues super fast and then will also detect minor issues.
2. When possible, use parallel testing in your infrastructure. It allows for multiple tests to run at the same time which in turn significantly cuts down on total time executed. This encourages faster feedback and frequent testing cycles.
3. In addition, observe test results closely and review failure patterns in full. Determine root causes instead of symptoms of failures presenting. Fix tests that fail for the wrong reasons immediately.
Regression Testing Tools
Modern teams leverage tools to enable regression testing to be done quicker and more accurately. Some of the more commonly used tools include:
- Selenium: Widely used in web automation.
- Cypress: Modern and rapid testing suited for web applications.
- TestGrid: Cloud-based, enabling web application testing alongside mobile.
- BrowserStack: Excellent for testing in parallel across several browsers.
- Applitools: Made for visual regression testing.
These tools ensure testers can run a regression test efficiently while catching visual or functional bugs before releasing.
Regression Testing Techniques
Below are the four regression testing techniques-
Retest All Technique
The retest all technique involves executing all the tests in the regression suite again. The benefit is that it offers complete coverage of the system’s functionality. The downside is that it requires an enormous amount of time to implement. This strategy is best for major releases and critical applications.
Test Selection Technique
The test selection technique focuses on running only tests that involve the code that was changed. It looks for tests that matter based on code and identifies tests that are associated with modified sections of code. The test selection approach can save a substantial amount of testing time while maintaining an adequate level of coverage.
Test Case Prioritization Technique
The test case prioritization technique runs the test cases that are high risk or involve the functionality that is the most critical in the application first. The purpose of this testing strategy is to validate the functionality that is most important early in the testing cycle.
This allows the practitioners to get a quicker identification of critical issues that need to be addressed in an application.
Hybrid Technique
The hybrid technique combines the two techniques of test selection and prioritisation for the greatest benefit. The hybrid technique will select qualifying tests based on the changed code and then further classify each test by prioritizing the tests by their importance. While the hybrid will be time-saving, it will still afford coverage of functionality from the regression suite.
Regression Testing and Automation
Automation is crucial for effective regression testing. Additional tests can run on repeat with little fresh effort required, which saves time and money.
Automation also allows for continuous regression testing, which ensures that you can validate every change before it is deployed.
Most QA teams build automated regression testing into their build pipelines to discover defects sooner and shorten their release cycles.
Benefits of Regression Testing
Regression testing has benefits beyond just catching bugs. Here are four key advantages:
1. Ensures product stability
It confirms that software updates haven’t broken your existing features.
2. Improves the quality of your software
Testing continuously leads to higher-quality software that performs to a reliable standard.
3. Saves time and effort
Automation means you can reduce the amount of manual retesting.
4. Improve customer satisfaction
A stable software product earns your users’ trust.
Disadvantages of Regression Testing
There are a few disadvantages to regression testing, despite its significance:
1. Regression testing can be time-consuming until automated.
2. Human error can be made during manual regression testing.
3. Over time, it can become troublesome to manage large regression test suites.
4. Test prioritization must be performed to avoid delaying releases if it isn’t done.
In order to mitigate these disadvantages, use regression testing tools and strategies on when to run certain tests.
5 Reasons Why Regression Testing is Important for Quality Assurance
Below are the 5 key reasons why regression testing is significant for quality assurance:
1. Regression testing enables software to be stable over the long run.
2.Regression testing allows a new feature to be implemented without breaking existing features. The value of regression testing becomes clear when we consider the uncertainties of any update.
3. Regression testing ensures end users are given predictable behaviour. After fixing a defect, the development team will always want to verify that their solution actually worked, but they will also want to verify that their change did not introduce a new malfunction.
4. Automated regression testing makes this verification happen much faster than manually running the tests.
5. An automated regression testing tool will quickly run many tests much faster than it could be done manually. This will allow for more frequent testing without slowing down the overall development work process.
Continuous Regression Testing
The term “continuous regression testing” refers to the automated regression testing conducted when a new build is released. This practice focuses on maintaining software quality assurance in real time.
This method works best with the DevOps methodology, as it produces a steady state with builds being deployed quickly and efficiently.
Automated Regression Testing
Automated regression testing employs the use of software tools to automatically run test cases without needing manual intervention. The scripts will perform the same validation steps in the same order each time they run, eliminating the potential for human error and minimizing the amount of time spent on the testing process.
Automation tools interact with the application in exactly the same way as a human user by entering data, clicking buttons, and verifying that expected outcomes occurred. The tools produce documents and detailed reports identifying test cases that passed in addition to the test cases that failed.
When to Automate Regression Tests
Automating regression tests that run often and rarely change is beneficial. Stable test scenarios will return the best value on your investment in automation. Tests associated with core functionality should also be automated to ensure regular validation of your critical functionality.
Data-driven tests, which require multiple input combinations, are good candidates for automation. Automated tests can often run hundreds of tests quickly with varying data. This allows for complete testing without taking any time away from a test analyst or tester.
It is not advisable to automate tests that change frequently or require human judgement to complete. UI tests that require visual assessment may not make sense to automate. You want your automation efforts to yield the housing for which you invest in automation.
Automation and CI/CD integration
In today’s world of software development, automated regression testing is now part of all continuous integration (CI) pipelines. Automated testing tools run pre-established scripts each time developers push code to detect failures as quickly as possible.
This mechanism keeps the development cycle moving quickly while guaranteeing that no defects have slipped through.
Regression Testing in Agile and CI/CD
The Agile way of working means that new features are introduced regularly. In this way, regression testing in Agile will ensure the stability and bug-freeness of each sprint release.
Automation becomes very important here since you’re going to be testing very frequently, after each sprint iteration. It is not uncommon for an Agile team to initiate their regression tests nightly using CI/CD tools.
In Agile, changes are rapid. Teams will do regression testing promptly after a sprint or commit.
In CI/CD, it is now part of continuous integration—ensuring that every build is stable.
This fits with test automation and facilitates quick and safe delivery.
How to Perform Regression Testing?
To conduct regression testing, the QA team determines which core modules are affected by the latest release. The QA team will select relevant test cases from the regression testing suite and validate the results.
Automation assists in accomplishing these tasks quickly in stable test environments.
Regression Testing vs Retesting
| Aspect | Regression Testing | Retesting |
| Purpose | Verifies that existing functionality still works after code changes | Confirms that specific defects have been fixed correctly |
| Focus | Checks for unintended side effects in unchanged areas | Focuses on the exact scenarios where bugs occurred |
| Scope | Broad coverage of existing functionality across the application | Narrow scope limited to previously failed test cases |
| Test Cases | Runs passed test cases to ensure they still pass | Runs failed test cases to verify they now pass |
| Timing | Performed throughout the development lifecycle after any code modification | Performed specifically after developers fix a reported defect |
| Frequency | Continuous and repetitive with every software change | One-time activity between bug identification and closure |
| Automation | Highly suitable for automation due to repetitive nature | Difficult to automate as it often requires human judgment |
| Test Selection | Includes test cases unrelated to recent changes | Only covers the specific functionality that was broken |
| Goal | Ensuring overall application stability and consistency | Validating the effectiveness of bug fixes |
| Priority | Lower priority compared to retesting in specific instances | Higher priority as it directly addresses known defects |
| Execution | Can run in parallel with other testing activities | Must be completed before the bug can be marked as resolved |
| Coverage Growth | Expands as the application grows with new features | Remains focused on fixed defects only |
Key Considerations
Regression testing and retesting are complementary testing processes for the evaluation of quality in software. Regression testing enables the testing team to ensure broad coverage when concern exists of the unintended impact of change. Retesting serves to confirm focus with verification that concerns have been fixed.
Due to the effectiveness of regression tests, teams should leverage, where possible, the ability to automate them to increase speed and consistency of execution. Retesting often involves more manual execution with careful verification of fixes. Both testing strategies are necessary experiences for a full quality assurance plan.
Measuring Regression Test Results
- You should analyze the results after each test run.
- In other words, note how many tests passed, failed, or were skipped.
- You should also maintain a record of the tests that continually fail, which may suggest underlying issues.
These observations provide you with valuable information to enhance software quality and keep the same bugs from happening again.
Challenges of Regression Testing
Though regression testing is an efficient automated testing strategy, there are several challenges:
1. Identification of the appropriate test cases: Determining which tests to run again is difficult.
2. Time Requirements: Many organizations are deploying buildings frequently and, in some situations, have to compress testing timeframes.
3. Tool Compatibility: Automation tools must work within the project’s tech stack.
4. Data Management: Test data must remain the same across environments.
Implementing a comprehensive regression testing strategy will help successfully address these challenges.
Real-World Example of Regression Testing
For instance, an e-commerce site that implements a new discount feature. Once the application is deployed, the checkout process must also function correctly.
Regression test cases help validate new discount logic while ensuring that existing payment and cart modules have not malfunctioned.
This demonstrates the benefit of regression testing for user reassurance and uninterrupted activities within a production application.
The Future of Regression Testing
With AI and machine learning, the future of regression testing is bright. Intelligent testing tools can now identify risky areas of code and can even automatically create test cases aimed at risk areas.
Tools incorporating AI, such as TestGrid AI and BrowserStack Smart Testing, are reported to reduce testing time frames based on analyzed historical regression information.
The next evolution of software testing will feature automation, analytics, and intelligence to achieve even quicker software releases.
Conclusion
In conclusion, regression testing is a key practice to ensure software stability and quality during the development life cycle. It prevents code changes from adversely impacting any existing functionality while giving teams the confidence to ship changes.
Effective practices for regression testing must implement the right blend of strategy, tools, and degree of automation to achieve the best combination of comprehensiveness and efficiency.
Frequently Asked Questions
1. What is regression testing in simple terms?
It is verifying that your software still functions correctly after you make any new changes or fixes to the software.
2. When should regression testing be done?
It should be done after any changes, whether large or small, are made in the code or the functionality of the software.
3. What are the best tools to use for regression testing?
Tools like Selenium, TestGrid, Cypress, and BrowserStack are good tools that many organizations use.
4. Does regression testing require coding?
Most automated regression tests, such as Selenium or Cucumber, require some basic coding skills. Although, there are a number of low-code or no-code testing tools that do not require any coding to perform regression tests.
5. What is regression testing vs retesting?
Retesting is basically confirming that a specific bug fix works, while regression testing simply confirms that it did not break anything else that was working.
6. What are the main types of regression testing?
Unit Testing, Partial Regression Testing, Complete Regression Testing, Selective Regression Testing, and Progressive Regression Testing.
