Regression Testing in Software Development

Regression testing is an essential practice in software development that involves retesting previously tested software functionalities to ensure that any recent changes or additions have not introduced new defects or caused regressions in the existing features.

Simply, regression tests are inspections done after modifications are made to live codes. These changes can be a fix for a bug, adding or removing a new function, or improving performance.

Regression testing plays a vital role in maintaining software quality assurance and delivering a consistent experience to end-users. In this article, we will explore the significance of regression testing in software development.

What is Regression Testing

After the software has reached a level, it may become less advanced with the addition or modification of new functions. Even a small change in the software or code of the product can cause various glitches, crashes, and serious malfunctions that indicate that the application does not work as desired.

The purpose of regression testing is to verify the correctness of the software by returning it to its initial configuration while verifying that the desired outcomes have been achieved. The influence that newly included features have on the previously developed code is investigated using these tests. In their most basic form, regression tests examine two factors after a change has been made:

Does the newly implemented change produce the desired results?

Are there any other functions that will be affected by this modification, even if they have nothing to do with it?

When Should Regression Testing Be Done?

Regression testing is done at the final stage before go-live and at critical points throughout the entire agile software development lifecycle after it goes live.

Regression testing is usually required in the following situations:

Adding/Removing Features

Features added or removed from existing software can produce bad results. Regression testing is commonly used in backend architecture to also identify issues with adding new features to customer needs.

Code Based Changes

After adding resource optimization, bug fixes and other possible changes, regression testing is required even if nothing important has been added or any of the client’s requests have not changed.

After Errors Occur

Regression testing enables the identification of seemingly insignificant changes in recent changes. It plays an important role in finding code errors that have already occurred or may occur.

Benefits of Regression Testing

Regression testing is useful at every stage of software development and lifecycle. The most important known benefit of regression testing is that it ensures that the software runs smoothly after code fixes, adding new features, removing or bug fixes.

Easy Bug Detection

Bug detection, which is one of the most useful benefits of regression testing, is easily detected in any change. Quick resolution of bugs also means positive customer feedback and fast progress.

When the software test team runs the regression tests, they can see if an error is received or the link of that error to other functions.

Ensuring Continuous Integration

Data from previous functional or non-functional tests tells us about the testing process. This will benefit us in automation testing.

The development teams establish continuous integration and the newly written codes are provided to run the desired scenario in the automation tests within the scope of the regression package.

Cost Reduction

Regression testing allows to reduce software development costs. The software also detects the problems after subsequent additions and eliminates the costs that will occur in the future. It saves time and money with automatic regression testing tools and minimizes the time spent on manual testing.

Regression Test Types

There are 7 types of regression testing that can be done manually.

Corrective Regression Test

Corrective regression testing is one of the easiest types of regression testing. It involves reusing a test case with no significant changes to the implementation. In other words, you can continue to run the tests without changing the test scenario. You can get information in case of a possible error.

Retest-All Regression Test

Retest—all regression testing is the hardest-seeming regression test. It is based on testing all the features of the application from the beginning (end to end). It tests the software from the very beginning to the smallest change.

With a retest scenario, it is possible to find problems that other test types cannot find.

Selective Regression Test

Selective regression testing is a test between corrective and retest-all regression tests. It allows testing by limiting where in a test scenario is affected by the change. 

Selective regression testing is used when testers know where the problem originates.

Stepwise Regression Test

In stepwise regression testing, new scenarios are written for newly added functions, allowing the tests to be retested.

Complete Regression Test

Full regression testing is used for significant changes that happen to the system. Full regression testing is important as there can be significant changes when the overall code is changed. This test covers all phases of software development.

Partial Regression Test

Partial regression testing is applied when the application wants to combine the codes with a larger part. Partial regression testing allows testing how each module works when combined with other modules while working independently.

Unit Regression Test

Unit regression testing is the easiest regression testing. It allows to test only one particular unit within the whole code.

How to Implement a Regression Test?

the initial step for a tester embarking on Regression Testing is the critical task of Error Detection. This pivotal phase involves meticulously identifying any discrepancies or flaws within the codebase. Once these errors are discerned, the subsequent step is the thoughtful selection of test scenarios, specifically targeting the area of the code that has been modified and impacted by these identified errors. It is through this strategic approach that the foundation for effective regression testing is laid.

Software maintenance plays a pivotal role in application development, encompassing tasks like error rectification, the introduction of new features, and the enhancement of existing functionalities. These changes have the potential to influence the application’s behavior, either positively or negatively, in relation to its intended operation. 

The imperative for Regression Tests becomes evident. In the broader context of QA test implementation, these tests serve as a safeguard against unintended consequences and deviations from the desired application behavior. Their systematic execution contributes significantly to the overarching goal of delivering a high-quality product, characterized by reliability and adherence to specified requirements. Hera are the regression test stages:

Retest All

Re-Test is one of the types of regression testing. In this approach, all test cases must be run all at once. If a test fails, a re-test is performed and it is found to be a software bug. After the error is fixed, the test is done again. It appears that the error has been fixed. This is retesting. We can call this the verified test. It is not preferred because it requires a lot of time and resources.

Regression test Selection

With this approach, regression testing of a selected test scenario is performed alone.

The selected test can either be reused (among other regression tests)

or the old test case has been and cannot be reused.

Prioritization of test cases

Test scenarios should be prioritized by looking at frequently used places and functionality of the function. Selecting tests by giving priority will reduce the burden of regression.

How to choose test cases for regression testing?

Selecting the Test Case for regression testing is not easy, certain criteria must be observed.

Regression testing can be done as follows:

– A repeating faulty test case

-Modules that users see and use most

-Test scenarios reveal the main lines of the product. Therefore, regression testing of all integration test scenarios can be performed.

-Complex and multi-module-related test scenarios

-Test scenarios with limit values

-The parts that are used very frequently and that can cause big problems if mistakes are made.

Regression Test Example

Regression testing should be performed each time the software code of the Product/Application is changed.

Below are examples of which scenarios regression testing should be performed.

Regression testing should be done when new functions are added to the application.

There is a function in the login section of a website that allows users to login with Email login only. Let’s say we run a regression test with 20 test scenarios until this part. 

A new function is added to the entrance by giving access to the website with Gmail. 20 more test cases are written related to this section and regression tests are performed for all of them with the newly added section.

The regression test is performed when any error is corrected on the application.

Let’s assume that the button where the student registration is not working in the module where the students’ information is kept on a website. The tester notifies the developer that this function is broken.

After the developer corrects the error, the tester tests the create button again. However, it should also perform a regression test on the parts that this part affects or does not affect.

When the application has a performance problem, regression testing should be done.

While the loading time of the most visited home page on a website is 10 seconds, it is not suitable for the user, and after it drops to 2-3 seconds, a regression test is performed.

Software Testing At NioyaTech

In conclusion, regression testing is a fundamental aspect of software development that should not be overlooked. It ensures the stability and reliability of software systems, even as they undergo changes and updates.

By conducting thorough regression testing, developers can identify and address any unintended defects or regressions, providing a consistent and reliable user experience.

At Nioyatech, we recognize the importance of regression testing and its impact on software quality. Our experienced QA team is dedicated to delivering comprehensive QA services, including robust regression testing, to help businesses achieve excellence in their software products.

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