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Home Guide What is the difference between Retesting and Regression Testing?

What is the difference between Retesting and Regression Testing?

By Sakshi Pandey, Community Contributor -

Table of Contents

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

Testing to find defects in the software not only helps ensure customer satisfaction but it’s also very cost-effective for the project. Finding flaws early on, prior to significant damage taking place, can help the developer save time, money, and effort down the line. 

Regression testing is essential to preserving the program’s quality since it assures that the code is functional after modifications or updates are made to the application. Retesting verifies that the code’s corrected flaws are functional. To reiterate, without thorough testing, it would be unfeasible to develop and maintain functional, high-quality pieces of software.

What is Retesting?

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

Retesting is when a test is carried out again on a specific feature that was known to not be functional during the previous test in order to check for its functionality.

An instance that may warrant a retest:

Retesting ExampleLet’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 back, 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 in order to validate its functionality.
  2. It can also be used to assert or verify to the developer that a specific module or component is non-functional.

To summarize, 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, it’s important to ensure that a butterfly effect hasn’t occurred. A small change in the application could lead to unintended defects elsewhere; Regression testing takes a generic blanket approach to look for these unintended defects.

Defining regression testing, it is a type of testing which 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 reaffirm, while retesting aims to check whether a specific bug has been fixed, regression testing simply 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.

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Retesting vs Regression Testing

RetestingRegression Testing
Retesting has tests designed specifically to check whether known bugs have been fixed.Regression testing isn’t targeted testing for known defects.
Retesting does not focus on previous version functionality, instead, it aims to check whether functionality has been restored following a bug fix.Regression testing is change oriented and mainly aims to check whether the previous versions’ functionality is maintained following a change/update to the application.
Since retesting checks for a specific defect, it can’t be automated. Automation is very popular for regression testing. Manual testing every time a change or update is made to an application would be very irrational. Automation is far more complementary to carrying out blanket tests looking for unintended bugs.
Retesting doesn’t have to be a part of the testing process unless a bug is found and corrected; Therefore, retesting is not a guaranteed part of the testing process.Regression testing is the norm and always a part of the testing process. Every time the application’s code is altered, it is good practice to perform regression testing.
A higher priority is applied to retesting since this kind of testing focuses on fixing known defects.Regression testing has a lower priority in comparison to Retesting since it simply conducts a sweep of the application to check for potential unanticipated defects.
Since only a certain defect is explored in retesting it is far less time-consuming.Regression testing often explores large parts of the application to uncover bugs and can therefore be more time consuming than retesting.

As seen in the table, while retesting and regression testing are both similar in that they are repetitive in nature, and seem to have an overlapping objective in an application, they are in fact, quite different. 

To summarize, the chief difference between regression testing and retesting is that retesting is meant to check for known bugs and is used to generally reaffirm that the bug in question has been fixed. Regression testing is different in that it is used to search the application for unknown bugs, which may have occurred due to some change implemented in the application.

Concluding Notes

Retesting and Regression Testing when fixing defects in a software

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 back 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, in order 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 which was 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 when testing, ensuring better accuracy. Testing on cloud-based tools like BrowserStack gives QAs access to 3000+ real device/browser combinations. Moreover, it supports integrations with several popular test automation frameworks such as Selenium, Cypress, Playwright, Puppeteer, and NightwatchJS. Browserstack also allows QAs to run Regression Tests and share the test reports among their team over Slack, Trello, or GitHub.

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