Automated Regression Testing: A Complete Guide

Imagine this: You’ve just rolled out a small update to your application, but suddenly a core feature stops working. Sound familiar? That’s where automated regression testing comes to the rescue.

When you automate your regression tests to run on schedule, it's like having a diligent, tireless assistant that constantly checks your software for unintended side effects every time you make a change.

Let’s dive into how automated regression testing can transform your software development process, saving you time, money, and effort.

What is automated regression testing?

Regression testing vs. retesting

Regression testing checks whether recent code changes have affected existing features, while retesting verifies that a specific defect has been successfully fixed.

Regression testing is broad, covering all related functionalities; retesting is narrow, focusing only on the failed test case.

Regression tests are often automated and run frequently; retesting is usually manual and run after a bug fix.

Here's a brief comparison of regression testing vs retesting:

Why automate regression testing?

1. Faster feedback loops

Automation testing in general gives you instant feedback on new changes, helping you detect and fix bugs before they become bigger issues. Instead of waiting for manual testers to sift through test cases, automated tests run swiftly after each code update. This means problems are identified early, reducing the back-and-forth between developers and testers, and ultimately speeding up your development cycles​. 
 

2. Cost and time efficiency

Manual testing is not only repetitive but also time-consuming and expensive. By automating regression tests, you drastically cut down on the hours spent manually re-running the same tests. Think of it as an upfront investment that pays off with faster releases and more efficient use of your team’s time. No more tedious manual work, just set it up, and let the tests run themselves​.

Some may counter this point with the argument that automation is costly. Indeed, it requires resources to set up, but automated regression testing saves significant time and effort in the long run.

3. Improved test coverage

Automated regression testing allows you to cover more ground, running thousands of test cases in the time it would take a manual tester to complete just a few. This means you can test more scenarios, edge cases, and environments without overwhelming your team, ensuring that every part of your software is thoroughly checked after each update​.

4. Consistency

Unlike humans, automated tests don’t get tired or overlook things. They run the same tests, in the same way, every single time. This level of consistency means you can trust the results and catch any regressions reliably, no matter how complex the environment. Whether you're testing on different browsers, operating systems, or devices, automation ensures that your software performs as expected across the board.

How to automate regression testing?

Step 1. Evaluate your regression testing needs

Start by identifying which parts of the application are most vulnerable to breakage. These are usually the areas that have been around for a while, have undergone multiple changes, or are used frequently by users. Ask yourself:

1. Which features are essential to the user experience?
2. Where do I often see bugs cropping up after updates?

These are the areas that need regression testing the most. If your software is complex, prioritization becomes even more important. Start with the most critical functionalities that users depend on daily. For example, in an e-commerce application, the checkout process is non-negotiable. It must be thoroughly tested each time.

From a technical standpoint, the process of evaluating your regression testing needs begins by auditing the existing test coverage. Use code coverage tools to identify which parts of your codebase have been tested and which haven't. However, don’t rely on code coverage alone; it’s not always a perfect indicator of quality. Instead, analyze historical defect data to pinpoint areas where bugs have historically emerged.

 Regression testing is typically performed in the following scenarios:

• A new requirement is introduced to an existing feature
• A new feature or functionality is implemented
• Defects in the codebase are fixed
• The code is optimized for better performance
• Patch fixes are applied
• A new software version is released
• Modifications are made to the User Interface (UI)
• Configuration changes are implemented
• Integration of a new third-party system with the existing system
   

Step 2. Choose the right test cases to automate

We know what tests to run. However, not all tests should be automated. 100% automation testing is a myth.

Why is that? Because some test cases are just not suitable for automation. Either they are too complex or too dynamic to automate efficiently. Imagine automating the a test case for your E-commerce homepage, which changes everyday, sometimes every minute. You're going to have to spend a LOT of time updating the test to reflect those changes.

Instead, what you should do is focus on stable, repetitive test cases that yield consistent results across multiple runs. For example, test scenarios like form submissions, login processes, and backend calculations are typically stable and ideal for automation.
 

📝 Read More: Top Test Cases For Login Page To Consider

Of course, there are certain scenarios where human intuition, creativity, and judgment are irreplaceable. Exploratory testing is a good example. Only after doing exploratory testing can you start test automation.

Step 3. Choose the right tools and frameworks

When it comes to automation testing in general (not just automated regression testing), you have 2 approaches to choose from:

1. Either you build a test automation framework
2. Or you leverage out-of-the-box test automation tools from vendor

There’s no right or wrong answer, really. It all depends on your team’s needs and anticipated growth rate.

Step 4. Run tests and review results

With your test cases ready, it’s time for execution!

With automated regression testing, there are several execution strategies:

• Batch Execution: You can group multiple test cases and execute them simultaneously, saving time and resources. These groups are known as "test suites," typically containing test cases with similar characteristics.
• Scheduled Execution: Once you have a test case management system in place, you can schedule tests to run at specific times. This is especially helpful for regression testing, allowing tests to run automatically at set intervals.
• CI Integration: Test cases can be set to automatically run within the CI/CD pipeline. Whenever a new build is generated, it triggers the test execution, immediately identifying any new bugs, reducing the need for manual oversight.

📚 Read More: How To Build a Good Regression Test Suite?

So we know what to execute and how to execute. Now we need to figure out where to execute:

The challenge here is that you may want to test on so many environments, but the company resources may not be able to accommodate all of that. Usually QA teams have 2 options when it comes to configuring test environments:

1. Option 1: Invest in real physical devices. This offers the highest level of realism, particularly useful for device-specific tests like battery performance and real-world usage. However, it can be quite expensive, given the number of devices QA teams need to cover for adequate test coverage.
2. Option 2: Start testing in the cloud. There are numerous cloud-hosted testing environments available on-demand for QA teams. These solutions enable testing across any browser, device, or OS, while scaling as needed, without the ongoing burden of maintaining physical infrastructure. Katalon TestCloud is a good example of a cloud-based testing tool.

📚 Read More: Emulator vs Simulator vs Real Device: A Comparison

Step 5. Maintain and update test suites

Here's a quick webinar to show you Self-healing can solve your test maintenance challenges:
 

FAQs on Automated regression testing

1. Why is it called regression testing?

It’s called regression testing because it checks for regressions, meaning it ensures new code changes don’t break existing features. It's like making sure you don’t accidentally go backward after fixing something or adding new functionality.

2. How to automate regression testing?

To automate, choose an automation tool like Selenium or Katalon Studio, and identify key test cases. Write automated scripts, integrate them into a CI/CD pipeline, and the tests will run automatically after each code update, ensuring the app stays bug-free.

3. How to reduce regression testing time?

You can reduce time by prioritizing critical test cases, running tests in parallel, automating repetitive tests, and removing redundant test cases. This helps streamline the process without sacrificing quality.

📚 Read More: How to reduce regression testing time?

4. What is the difference between retesting and regression testing?

Retesting focuses on checking whether specific bug fixes worked, while regression testing checks that the new code didn’t break anything else in the system.

5. How long should regression testing take?

It depends on the project size, but it can take hours or days. Automation speeds up the process, ideally fitting into your development cycle without causing delays. The faster, the better!

6. What tools support AI-powered regression test selection?

AI-powered regression test selection is supported by tools like Mabl, AutonomIQ, and Katalon TrueTest. These tools use machine learning to prioritize and select the most relevant test cases based on code changes, historical data, or failure trends, reducing test execution time and focusing on high-impact areas.

Katalon TrueTest is an especially new way to do automated regression testing. It approaches regression testing by analyze real user behavior, then use AI to turn those real user insights into regression test suites. Read more about TrueTest here.

7. How often should I update my regression test suite?

You should update your regression test suite after every major feature release, bug fix, or refactor. Frequent updates ensure your tests reflect the current functionality of the application and help avoid false positives or missing coverage for new features.

📚 Read More: How to build an effective regression test suite?

8. What’s the difference between sanity tests and regression tests?

Sanity tests are quick checks to verify that a specific bug fix or change hasn’t broken core functionality, often run before deeper testing. Regression tests are broader, ensuring that recent code changes haven't negatively affected any existing features throughout the application.