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When to Use Automated Regression Testing

What is Regression Testing?

Regression testing in software testing ensures changes and additions to code have not introduced new issues into previously working functionality. A software regression is any unwanted change that occurs from code changes. A real-world example is when you take your car to a mechanic to get the air conditioning fixed, and you get it back with the air conditioning fixed, only to find the gas tank sensor no longer works. Bummer.

To raise the stakes further, imagine you’re working on an airplane engine. You need to replace a component – say, a turbine disc. After you’ve done the job, you wouldn’t just check that the disk works in isolation; you’d also test the entire engine to ensure everything else functions as expected. For example, you’d want to ensure that you haven’t accidentally impacted how gases leave the combuster, that the compressor still maintains proper cabin pressure, or that the new disc didn’t cause any other damage.

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Given that regression is an unintended change, then regression testing is the process of hunting for these changes. Then regression testing, by definition, simply checks for any unintended issues caused by code change.

What is Automated Regression Testing?

With automated regression testing, a development team creates and executes automation test scripts to check whether any new changes have resulted in unintended side effects. Typically, the software development process uses test scripts that simulate user actions while working with the app. The team may also focus on critical functionalities and specific workflows central to the user experience. 

Automated regression testing has some advantages over manual testing, especially when you need continuous testing. With automated regression tests, you:

  • Eliminate the need to execute test cases one by one manually
  • Save time and resources during the software development life cycle
  • Reduce the chances of human error corrupting your test results
  • Enable seamless integration of your testing process in your development pipeline

As a result, you improve the software development process, producing more reliable iterations in less time using fewer resources.

Why Should Regression Testing be Automated?

The words “automated” and “regression testing” go hand-in-hand. When companies consider maximizing their QA teams’ potential through automation, they look to regression tests. 

  • Stable
  • Repeated frequently
  • Simple
  • Worth maintaining

Because regression testing is for existing functionality, it requires constant repetition. Every release cycle should include a fair amount of regression testing to ensure new developments don’t introduce bugs or break functionality.

Choosing Test Cases for Automated Regression Testing

The question of what to automate depends on individual applications. Still, a good starting point when determining regression test candidates is to ask which system components have been affected by a code change.

With each new release, you can list out or create a mind map for affected areas. Then, you can decide which cases are repeatable and worth maintaining at the unit, integration, and system testing levels.

To explain the test cases, we’ll look at automating regression tests for an e-commerce website that recently added a discount coupon feature. Here are the top 8 test cases selected, tied with the regression testing strategy:

  1. Cases with frequent defects: User registration often had login errors. The login process needs thorough regression testing to ensure seamless user access.
  2. Obvious functionalities: Product browsing, a highly expected feature, must be tested to ensure the product information is correctly displayed.
  3. Cases that verify core features of the product: The checkout and payment process, a core e-commerce feature, requires testing to maintain trust and reliability.
  4. Cases of functionalities that have undergone recent changes: The newly added discount coupon feature requires rigorous testing to ensure it functions as intended.
  5. All complex and integration test cases: The shopping cart function, integrated with multiple features (product browsing, checkout, payment gateways), needs detailed testing to avoid failures.
  6. Boundary value test cases: Testing edge cases, such as maximum and minimum quantities for product purchases, ensures the system can handle limit conditions.
  7. A sample of successful test cases: Test user registration and successful purchase with a discount coupon is essential for a smooth user experience.
  8. A sample of failure test cases: Attempt invalid actions such as applying expired discount coupons or registering with an existing email to confirm error handling.

Determining Test Case Reusability

To save time and cost, it’s also important to categorize your regression test cases according to whether they’re reusable, obsolete, or likely to drift into obsolescence. Reusable tests are great candidates for test automation, while obsolete tests aren’t unless you test for backward compatibility. 

As you design your automation test suite, it’s also essential to document the criteria chosen and the team’s thinking around each choice so everyone understands not just the ‘what’ but the ‘why.’

To identify reusable test cases, you can focus on those that:

  • Cover core functionalities or processes that are unlikely to change
  • Validate workflows that several versions of your software—or future apps—are likely to incorporate
  • Cover integration, security enhancements, or other common changes you’re likely to incorporate down the road

On the other hand, as you review your regression test selection, obsolete test cases may involve those that:

  • Cover functionalities you’ve removed from the software
  • Cover app elements that are no longer valid due to changes in the software’s architecture or workflows
  • Duplicate the functions of other test cases

How to Automate Regression Tests

To automate regression test, you have to:

  • Understand the requirements: This involves identifying which parts of your app require regression testing and the extent of changes each release brings. You can then use this information to determine which test cases to automate.
  • Pick your test tool: When selecting a test automation tool, consider compatibility with your application, integration with other tools, ease of use, scalability, and support for all potential test cases.
  • Automate test cases: Automating your test cases may involve segmenting them into smaller scenarios and developing automation scripts. 
  • Prepare your regression suite: Your automation regression test suite should cover all necessary functionalities, areas prone to regression, and those that significantly impact the user experience.
  • Run your test suites through CI/CD tools: By running your regression testing techniques through CI/CD tools, you automate the test process within your overall software development lifecycle. This requires configuring your CI/CD tool to trigger your regression tests automatically. You should also monitor the results to identify failed tests or errors.

Automated Regression Testing Tools

Automated Regression Testing Services

In the long run, automated testing can save an organization money spent on human resources, but only if they are fully prepared for the investment. 

  • Alignment and integration of your engineering workflows with the automated software testing service’s testing process
  • The design, build, and maintenance of accurate test scripts
  • The management of test runs and setups for you
  • The review and validation of test results and defects while also taking care of noise and flaky tests
  • Real device utilization
  • Access to build management tools
  • Automation run systems
  • The integration of reporting and insights

Some benefits are:

  • Fit automated testing into an overall test strategy
  • Get results continuously and for upcoming releases
  • No need to commit human resources
  • No risk of forfeiting ROI with inevitable organizational changes

If a customer asked you to demonstrate to him, within an hour, that your newest software is ready to use, what tests would you run? Are these the same tests that you are now performing in your first hour of regression testing? They should be.

Steven Woody

Challenges and How to Overcome Them

As with other forms of automation, regression testing is subject to the challenge of test case maintenance. 

The Power of Crowdsourced Testing

For example, a popular hotel accommodation provider with over 10 million installations outsourced their regression testing to Testlio’s network to augment their small in-house QA team. What previously took the internal team three weeks to complete is now accomplished over weekends through crowdsourcing. This process is more efficient than hiring additional full-time testers and provides the speed and flexibility necessary for continuous development initiatives in today’s fast-paced environment.

  • Twenty (20) testers to work in two to three-hour bursts to knock out the regression testing over weekends
  • POS and localization testing
  • Comprehensive device, OS, and real user app version upgrade coverage, as not all of their users immediately install the latest updates

Practicing Selectiveness

  • What features and functions are affected by new code?
  • What is the minimum amount of test cases that can cover the maximum amount of code?
  • Which unit-level tests can be merged or eliminated?

By always (always!) being selective about what test cases require automation in the first place, you create a more stable automation suite that is less subject to inevitable software changes.

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