Difference between Retesting and Regression Testing

Ensuring that a piece of software meets a need of the target audience is the primary goal of software development. It is essential to ensure the application is dependable and effective and delivers high-quality content to guarantee consumer happiness. Thus, software testing is one of the most important facets of building a product that the consumer can trust. 

Retesting and regression testing are two different types of software testing, but they are often confused.

• Regression testing: Tests a software application or system to ensure that changes (such as bug fixes, enhancements, or new features) do not cause unintended side effects or regression errors in previously working functionality. It involves rerunning once-executed test cases to ensure they still pass after the changes are made.
• Retesting: on the other hand, retesting is the process of testing a previously failed test case after its defects have been fixed. The retesting aims to confirm that the defects/bugs have been fixed and that the affected functionality works as expected. 

However, for those looking to understand the intricacies of Regression testing vs Retesting, let’s get into the details with examples in the following sections.

What is Retesting?

Test engineers often find bugs while testing software applications; it is, after all, their undertaking to do so. After assigning these bugs back to the developers, they need to check if the bug is fixed. This is called retesting. 

Retesting is when a test is performed again on a specific feature not functional during the previous test to check for its functionality. Retesting is typically performed by the same testers who identified the defect in the first place.

An instance that may warrant a retest:

• Let’s take an example of an eCommerce website selling phones. While conducting tests regarding the functionality of the elements, it was found that the like button for the products wasn’t working.
• Upon flagging this error, the test engineer will task the developer to fix the defect.
• Once the developer reverts, the test engineer would need to retest and check if this specific feature has been fixed and is working as it should.

When to use Retesting?

1. Retesting can be used to test a specific component to validate its functionality.
2. It can also assert or verify to the developer that a module or component is non-functional.
3. Retesting can be done for various reasons. However, the common purpose of any retest is to repeat a test and confirm the existence or non-existence of a particular defect.

What is Regression Testing?

When a developer introduces updates or changes to the software, ensuring that a butterfly effect hasn’t occurred is essential. A small change in the application could lead to unintended defects elsewhere; Automated Regression testing takes a generic blanket approach to look for these unintended defects.

• Defining regression testing is meant to reaffirm that no unintended regressions or defects have occurred due to an update or code change in the application.
• The keyword being reaffirmed, while retesting aims to check whether a specific bug has been fixed, regression testing tries to do a catch-all test to affirm that no unintended bugs have occurred in the application.

When to use Regression Testing?

1. There is an update or enhancement carried out on the application.
2. A defect found in the application is fixed.

In CI/CD pipelines, regression testing is done by including a partial or sometimes full set of test cases that have already been carried out on an application and repeating them. This sounds very similar to retesting; however, where retesting looks to check whether specific known defects are fixed, regression testing looks for unanticipated defects in the application.

Retesting vs Regression Testing: Key Differences

• As seen in the Regression vs Retesting comparison table, both are similar in that they are repetitive and seem to have an overlapping objective in an application; they are, in fact, quite different.
• The core difference between retesting and regression testing is that retesting is meant to check for known bugs and is used to reaffirm that the bug in question has been fixed generally.
• Regression testing is different because it searches the application for unknown bugs, which may have occurred due to some change implemented.

Key Takeaways

• To drive the point home, let’s look at an example. Let’s say that a software test engineer conducts a test and finds a defective textbox that prevents the user from logging in.
• The issue is reverted to the developer, who fixes it. The tester will then retest to check for that particular textbox’s functionality. 
• Following this, a regression test will be carried out to check for other errors to ensure that everything is working following the fix.
• If another bug is found during this test then it will be flagged and sent back to the developer for correction and lead to another retest. Thus another iteration will be carried out until the application passes the regression test and no more defects are found.

So retesting and regression testing often occur within the same testing process and go hand-in-hand. However, as illustrated earlier, they have differing purposes. Retesting is done to check that the initial bug found and fixed is working as it should, while regression testing is used to sweep the application for defects that may have arisen from the change or other unknown residual bugs. Whether performing Retesting or Regression Testing, it is always recommended to test on real devices, so that the real user conditions are accounted for, ensuring better accuracy.

• Testing on a real device cloud like BrowserStack gives QAs access to 3000+ real device-browser-OS combinations.
• Moreover, it supports integrations with several popular test automation frameworks such as Selenium, Cypress, Playwright, Puppeteer, and NightwatchJS.
• BrowserStack also allows QA to run Regression Tests and share the test reports among their team over Slack, Trello, or GitHub.
• It is possible to conduct Selenium Regression testing, Python Visual Regression Testing, and Cypress Visual Regression testing, amongst many other frameworks, on BrowserStack.

Run Automated Regression Tests

Also, learn about the magic of visual regression testing and how Canva uses visual regression testing to test at scale.