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Blog

Regression Testing In Agile - How to Do It Right?

16 Oct 2019

For those not familiar with the term, regression testing entails re-testing a piece of software after recent changes or modifications to ensure that the product functionality wasn't altered in any negative way. 

In this article, we will investigate how to incorporate regression testing in Agile.

Why is regression testing important?

As you may already know, there isn't a single piece of software in existence that's 100% bug-free. A certain level of functionality must be achieved and proven through proper testing. In traditional methods, the testing phase would be conducted separately and only after the development phase had been completed. 

In Agile projects, however, testing is conducted simultaneously with the development and writing of the code. Now, regression testing, as mentioned before, is conducted after changes have been made to the existing software that's already been tested previously. 

These changes may include bug fixes, performance issue fixes, adding new features and so on. Adding new functionalities or fixing something can create new bugs, which can affect the performance and functionality of the existing, tested software. 

That's why it's very important to conduct regression testing after every modification so that the teams don't miss out on any critical bugs. 

How is regression testing conducted in Agile projects?

Agile software development is adaptive and incremental. The team creates a working piece of a product and new features and technicalities are added continuously. That means that software testing is growing and becoming more complex as the project moves forward. 

The main reason is that testers need to ensure that the functionality and the performance of software don't change with each new Sprint, in the case of Scrum. Aside from that, Agile projects thrive on feedback. Management or stakeholders may decide to include something new into the software. After all, Agile methodology welcomes and embraces changes even midway through the project. 

Each and every modification requires for the software to be re-tested again. That's why regression testing in Agile is crucial, but can also become complicated to incorporate.

Building a regression testing strategy

For an effective regression testing strategy to be built, a few things need to be considered. Here's an example.

  • You must identify which test cases should be executed.
  • Determine which improvements should be made to the test cases.
  • Identify the time it will require to execute regression testing effectively.
  • Consider which aspects of testing could and should be automated.
  • Set aside time to analyze the outcome.

After that is set and done, testers must also determine which methods work best for regression testing. Here's another example.

  • Re-test everything - Every test case is re-executed on the new codebase. However, this method requires both time and resources, which isn't viable when large codebases are involved.
  • Selective regression testing - Instead of testing everything again, it's possible to select a specific subset of your test cases that can be re-executed. This can also help you categorize test cases as reusable test cases and obsolete ones.
  • Prioritizing regression testing - Ideally suited for large codebases, prioritized regression testing focuses test cases based on business impact, areas of functionality believed to contain bugs, as well as priority. This greatly reduces the entire regression testing suite. 

Furthermore, not everything can be tested manually. It would simply take too much time and effort do test every functionality, every feature and every change. 

That's why automation is also an integral part of regression testing. However, even automation is not without its flaws. You simply cannot expect a 100% automated coverage. 

In other words, both manual and automated testing is required in the regression process.

Regression testing challenges in Agile projects

Every time regression testing is used in Agile projects, there's a chance that the teams will face some kind of a challenge that may set them back. As an example, here are a few challenges specifically common for automation.

  • Maintenance - Automated test cases cannot and will not be valid for an indefinite period. In other words, they require maintenance. More specifically, testers need to update automated test cases and modify them based on improvements and changes in the project. Simply put, obsolete test cases need to be removed.
  • False positives -Regression tests report bugs in the software even though there's nothing really wrong with it. That's when you play a game of find a culprit in the sea of culprits. Finding the source of this issue can be challenging and time-consuming. The flaw can be anywhere from a timing issue to a poorly coded test case. 

Aside from automation, other challenges may present themselves during regression testing. Here are a few of them that are the most common.

  • Frequent changes - Customers, stakeholders or managers introduce excessive changes that wipe out entire iterations. Any automated regression test strategy is at risk at this point.
  • No record or playback testing tools - You must wait to use traditional test-last tools that have a record or playback features until the functionality is ready. In other words, traditional automated testing cannot be used in an Agile environment.
  • Test growth - Regression testing grows significantly after each sprint, up to the point where it's no longer possible to do it quickly. Testers must, therefore, make an effort to keep the testing at a manageable level by optimizing test cases frequently and removing obsolete cases.
  • Ineffective communication - Agile teams thrive on collaboration and communication. Without effective communication between testers, developers, business analysts and stakeholders, any changes made to the software may go untested, which can create serious problems in the future.
  • Specialized testing skills - The more a project grows the more need for specialized testing skills is required. This is especially true when performance and integration testing is involved. Therefore, the team should have a specialized tester from the very beginning or at least have one within the organization that can help out when needed.
  • Maintaining the test cases - Automation helps verify the quality of the functionality as more test cases get automated. However, more automation requires more maintenance. Make a test too loose and it may pass a bug along. On the other hand, make the test to strict and you'll have to update it after every small change.

Closing word

Regression testing is essential in an Agile environment. However, in order to do it right, testers must focus on bot the efficiency and speed of test cases. Without a solid strategy, more issues and challenges may occur during the course of an entire project.