What is Regression Testing?
There are lots of explanations of regression testing. However, test IO
takes a slightly different approach. To us, a regression test is exactly that — a real test — not merely a checkbox. It can’t be a last minute or haphazard part of the process. After all, each change to the code presents a risk to customer experience. Effective regressive testing can reduce these risks, and human-powered regression testing is fast and accurate.
Put simply, regression testing is a form of software testing that confirms or denies the software components’ functionality after system changes. This kind of testing also finds bugs you may have introduced unintentionally by changing the software.
For instance, a software application may allow teachers to add, save, delete, and refresh in an online learning tool. Then, developers release a new version with an added functionality for update. The new functionality is tested to confirm that update works as expected.
But this ‘happy path’ testing hasn’t addressed whether the new functionality presents new issues within the existing code. In this case, regression testing can improve the quality of the product overall. It also ensures that bugs found earlier in the process are not being recreated in the code.
When adding features, refactoring, or fixing other bugs, it’s crucial to make sure you haven’t broken anything. You also don’t want to uncover problems that were previously hidden. A defect identified after the software changes is known as a ‘regression bug’. Even after you discover and fix a regression bug, there is still a need for further testing. You need to confirm that dealing with one bug doesn’t breed other issues.
Regression testing is necessary, even when making very small changes to the code. Forgoing this testing for unexpected issues could undermine both the success of the software and customer satisfaction.
When should you use regression testing?
Ideally, you should perform regression testing after making any changes to the code. Regression tests are also typically executed whenever a previously discovered issue has been fixed. After all, there can be many dependencies in a newly added and existing functionality. It is helpful to test whether or not new code complies with old code, and that unmodified code is not being affected.
The frequency of regression testing varies from project to project. However often you perform regression testing, it’s a good idea to have a schedule. For example, after every change, at the end of every day, weekly, bi-weekly, etc. Generally, the more often regression testing occurs, the more issues can be discovered and resolved. Frequent testing means your application will become more stable and production-ready.
Regression testing should also be a continuous process. Previously conducted tests should be run again, and their results can be compared to current test results. However, when regression testing implementations focus primarily on automated functional tests
, tests tend to be rather volatile and unstable. They often require a good deal of personal intervention. Developers or QA managers end up needing to babysit the test suite and confirm the performance and the results.
That’s why exploratory testing
should also be standard before the system goes into production. Through crowdtesting
or other methods, this exploratory testing can empower more creative examination to unveil issues not previously considered.
Proper regression testing methodology
There are typically three methods for regression testing:
1) Re-test all: This refers to re-testing the entirety of the software from top to bottom. Automated tools can perform the majority of these tests, but this is not always feasible or necessary. Plus, relying only on automation ignores the benefits of human testing and any chance for exploratory testing.
2) Regression test selection: This method allows the team to choose a representative selection of tests that will approximate a full test. This requires far less time or cost than the full test suite.
3) Test case prioritization: With limited test cases, try to prioritize those tests that could impact both current and future builds of the software.
Adding an exploratory testing phase
Unfortunately, regression testing commonly focuses solely on test success rates, whether automated or manual. Yet regression testing must fully evaluate if this indicates the software is functioning as expected.
In some instances, making changes to fix bugs can uncover functional problems that were not previously addressed. And making too many changes to the code base in too short a time span often leads to software instability. This could also introduce bugs and much higher fault rates.
In regression testing, volatile test results waste time as developers work to locate the issue and find a solution. In worst case scenarios, these tests become build-breakers, preventing the next iteration from moving forward as scheduled. Adding an exploratory phase in regression testing is a simple, yet powerful, step that can greatly improve software quality. This can help catch an unknown issue, even where a test case indicates no such issue exists.
For example, a web project might have a few standard registration fields that users can fill out. At some point during regression testing, a bug is discovered that prevents the nickname field from being displayed. The code can be fixed to make the nickname visible. However, many previous developer decisions with contingent implications on the code may have been made. This means other elements of the application will likely break during the fix.
Even more likely is the possibility that the hidden nickname field was a masked defect. Test cases for this issue simply didn’t exist before. Thus, regression testing now requires someone to closely examine all related test cases. They may need to create new ones or alter existing cases to account for this new field.
Limits of automated regression testing
Automated regression testing can be a powerful tool when used correctly. But test quality depends on the quality of the test design. Poor test design can lead to poor requirements coverage, wasted development time, and time-sucking false-alarm build breakages.
Relying on regression test automation to test the UI and user functionality of the product should be a last resort. User interfaces, by their very nature, are extremely volatile. Even when the functionality behind the UI is working correctly, minor changes can cause test failures. Instead, automated regression tests should focus on the product’s low-level layers: unit testing, the API, and service integrations.
Maintaining a smaller test suite is also particularly important when dealing with automated functional testing suites. Regression testing often requires test suite execution with every build and every project change.
Finding the right balance between the overall coverage for automated regression testing and the speed of the test suite can be challenging. You might want to use a minimization technique, such as the greedy algorithm
. It allows you to easily reduce the size of your test suite in a logical manner. This will enable you to identify tests that cover the broadest spectrum of faults. Then you can loosely prioritize tests within the suite based on that coverage.
Best practices in regression testing
1) Maintain a schedule: Choose a schedule of testing you can maintain throughout the software development life cycle. This avoids cases where testing is placed on the back burner.
2) Use a test management tool: Properly track all tests being performed on a regular basis, and have historical records of their performance over time. Do this using a simple test management tool of some kind. This can lead to more efficient decisions about what test cases must be executed. It can help pinpoint necessary improvements and changes in test cases. It can also drive clearer analysis of the regression testing outcomes.
3) Evaluate test prioritization: Regression testing is more difficult when the application’s scope is large and there are continuous increments or patches to the system.
Crowdtesting to advance regression testing
Crowdtesting before a major release can be extremely beneficial. Automated tests can handle some things, but humans can deal with the more volatile and subtle tests. Testers may reveal masked defects or even point to improvements. This saves a great deal of unnecessary coding time during further development.
With test IO, organizations can gain a broad-spectrum sweep offering a fresh perspective for increasing confidence every time you ship. test IO uses crowdtesting capabilities to run test cases in parallel, via many testers across many devices and platforms. This saves time for software developers and also lowers costs.
test IO’s skilled testers discover things you don’t expect, while making sure what you do expect actually works. Don’t settle for click-work. Demand insight. With our simple, scalable, and flexible crowdtests on a flexible, powerful platform, you can be testing in minutes.