Automated Regression Testing: A Complete Guide

Regression testing is crucial to any well-functioning CI/CD pipeline, but without some automation, it takes up a lot of time and effort.

When you automate your regression tests to run on schedule, it can constantly checks your software for unintended side effects every time you make a change, which saves a lot of resources.

Let’s explore how automated regression testing can transform your software development process.

What is automated regression testing?

Why automate 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. In other words:
• 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:

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

To automate regression tests, you have two approaches:

1. Build your own test automation framework

2. Use an automation testing tool

Building your own test automation framework means creating a customized system that defines how tests are structured, executed, reported, and maintained. Instead of relying on a vendor’s architecture, your team builds everything from the ground up, with your own libraries, utilities, helper functions, and the logic that powers your test suites.

You also manage environment setup and teardown, determine how tests run in CI/CD, implement reporting and logging, and choose the patterns that govern test design (such as POM, Screenplay, or BDD). As the product grows, the framework must evolve with it, so ongoing maintenance becomes part of the work.

Pros of building your own framework include:

• High levels of customization

• A workflow tailored to your domain and architecture

• Long-term flexibility and control

But the tradeoffs are real:

• Significant time and engineering investment

• Continuous maintenance requirements

• A slower path to initial value

This approach is ideal for teams with strong engineering capacity, a complex product, or long-term scalability needs.

The second path is adopting an out-of-the-box regression test automation tool. Vendor solutions come with core capabilities already built and optimized: test authoring interfaces, automated execution engines, reporting dashboards, pipeline integrations, and support for multiple testing types (UI, API, mobile, load, depending on the platform). Many also include low-code or record-and-playback features, and they typically offer built-in mechanisms to adapt to application changes, which reduces maintenance effort.

Advantages of this approach include:

• Faster onboarding and quicker time-to-value

• Lower engineering overhead

• Easier contributions from non-technical testers

• Ongoing updates, documentation, and vendor support

However, the limitations are worth noting:

• Less flexibility than a custom-built framework

• Potential fit issues for highly specialized use cases

• Licensing and scaling costs

• Limited extensibility in some tools

This route works best for teams that want immediate productivity, have fewer engineering resources, or need to empower manual testers to contribute quickly.

Step 4. Run tests and review results

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

Tools to automate regression testing

Many automated regression testing tools help teams design test cases, execute them across environments, integrate with CI/CD pipelines, and produce detailed reports. By supporting parallel execution, these platforms dramatically reduce testing time and improve overall efficiency.

Some widely used tools include:

• Katalon: A unified automation platform for web, API, mobile, and desktop testing. Katalon offers low-code scripting, built-in test management, powerful analytics dashboards, and seamless CI/CD integration. It’s ideal for teams that want fast automation adoption without heavy framework engineering.
• Playwright: A modern end-to-end testing framework from Microsoft that supports Chromium, Firefox, WebKit, and mobile emulation. It’s known for speed, reliability, auto-waiting, and strong support for parallel execution. Playwright’s cross-browser flexibility makes it a strong choice for UI regression testing.
• Cypress: A JavaScript-based testing tool built for modern web applications. Cypress runs directly in the browser, providing fast execution and rich debugging capabilities. It’s especially useful for frontend teams working with React, Vue, and Angular.
• JUnit / NUnit: Popular testing frameworks for Java and .NET applications. They’re often used to build robust backend regression suites, integrate with CI/CD systems, and support parameterized testing.
• Postman: While commonly used for API exploration, Postman is also powerful for automated API regression tests. Collections can be executed via command-line or CI pipelines, making API regression testing faster and more manageable.
• GitHub Actions / GitLab CI: Though not testing tools themselves, these CI/CD platforms play a critical role in scheduling and automating regression test execution across environments, ensuring tests run consistently with every commit.

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.