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What is Regression Testing? Working & Types

  • Utsav Mishra
  • Jul 07, 2021
What is Regression Testing? Working & Types title banner

When new software is introduced, it is apparent that new functionality must be tested. It's also critical to re-run old tests that the program passed earlier. That way, we can be certain that the new program does not reintroduce previous bugs or add new ones. Regression testing is the term for this sort of testing. 


Regression as we know means returning to the old state of something. The same thing is done in regression testing. In this blog, our main focus will be on learning regression testing in detail.



Regression Testing


Regression testing is a type of black-box testing used to verify that a software code modification does not affect the product's existing functioning. Regression testing ensures that a product's new functionality, issue patches, or other changes to an existing feature operate properly.


Regression testing is a form of software testing. Test cases are re-run to ensure that the application's previous functionality is still operational and that the new modifications haven't introduced any issues.


When there is a major change in the original functionality, regression testing can be conducted on a new build. It guarantees that the code continues to function even when modifications are made and refers to re-testing the elements of the program that haven't changed.


The Verification Method is another name for regression testing. Many test cases are automated. Test cases must be performed several times, and manually executing the same test case over and over is time-consuming and tiresome.


(Must check: Interoperability Testing)




Suppose a product X is there and its main function is to add new payment methods. At the time of adding payment methods, the product needs to be tested and codes need to be re-run to ensure that any changes in the code haven't affected the product module. 


It is to check that the old bugs are still there or not and if the same old problem is persisting or not. Regression testing is necessary since it's easy to put intended changes into a system that cause more issues than they solve without it.


(Read also: What is Risk Management?)


Benefits of Regression Testing


Companies profit from regression tests in a variety of ways, including:


  • Enhancing the likelihood of discovering problems caused by software and application modifications.

  • Aid in the early detection of problems, lowering the cost of resolving them.

  • Assist in the investigation of undesirable side effects that may have emerged as a result of a changing working environment.

  • As a result of the early detection of flaws and defects, the program performs better, most significantly, it ensures that modifications to the code do not reintroduce previous flaws.

  • Regression testing guarantees that the software is correct, allowing the best version of the product to be sent to market.



Conditions to Apply Regression Testing


In the following case, regression testing can be performed:


  1. When the program receives new functionality


For example, a website offers a login feature that allows users to log in using simply their email address but it has now added a new option that allows you to log in using Facebook.


  1. When a Change Is Necessary


For example, the previously relevant remembered password is deleted from the login page.


  1. When the flaw has been corrected


Consider the following scenario: a login button on a login page isn't working, and a tester files a bug claiming that the login button is broken. Once the problem has been resolved by the developers, the tester verifies that the Login Button is functioning as intended.


  1. When there's a fix in the performance issue


For example, a home page takes 5 seconds to load; by decreasing the load time to 2 seconds, the load time is cut in half.


  1. When there is a change in the environment


For example, when we switch from MySql to Oracle as a database.


(Recommended blog: Compliance Testing)



5 Types of Regression Testing


Regression testing is carried out in various stages. As a result, there are numerous different forms of regression testing. The following are a few of them:

The Image is depicting different types of Regression Testing, they are Unit Testing, Progressive testing, Selective testing, Reset-All Testing, Complete Testing.

Types of Regression Testing

  1. Unit Testing


When a tester, generally the developer responsible for the code, makes coding changes to a single unit, all previously successful unit tests are re-run. Automated unit tests are incorporated into the code in continuous development environments, making unit testing far more efficient than other forms of testing.


(Most related: Agile Software Development (SDLC))


  1. Progressive Testing


When modifications are made to the software/application requirements and new test cases are created, this form of testing is effective.


  1. Selective Testing


To save the expense and labour of retesting, testers employ a subset of the current test cases in selective testing. If and only if any of the software entities it covers have changed, a test unit must be repeated.


  1. Retest-All Testing


This testing method entails testing all elements of a specific application as well as recycling all test cases, even if no changes have been made. It takes a long time and is of little value when the program is modified or changed in any way.


  1. Complete Testing


When many modifications have been made to the current code, this testing is quite beneficial. This testing is quite beneficial in identifying unexpected issues. The finished system can be made available to the user once this testing is done.


(Referred blog: Types of Agile Methodologies)



How can do Regression testing?


When software maintenance includes additions, error repairs, optimization, and elimination of existing functionality, regression testing is required. These changes may have an impact on the system's operation. In this situation, regression testing is required.


The following approaches may be used to do regression testing:

The Image shows how Regression testing works, first the build is provided and then we run the test and the end result shows us that if the bugs have been fixed or not.

The Working of Regression Testing

  1. Re-Test


One method for performing regression testing is to use Re-Test. All test case suits should be re-executed in this method. We may define re-testing as when a test fails and the reason for the failure is determined to be a software flaw. After the problem has been reported, we may anticipate a new version of the program with the issue repaired. 


In this scenario, we'll need to run the test again to ensure that the problem has been resolved. This is referred to as re-testing. This is referred to as confirmation testing by some. The re-test is quite costly since it necessitates a significant amount of time and money.



  1. Regression Test Selection


Rather than running the complete test-case suite, this approach runs only a subset of the test-case suite.


The chosen test case is split into two parts:


  • Test cases that may be reused.

  • Test cases that are no longer valid.


Reusable test cases can be used in subsequent regression cycles, test cases that are no longer valid cannot be used in subsequent regression cycles.



  1. Prioritization of Test Cases


Prioritize the test case based on the business effect, key functionality, and frequency of use. The regression test suite will be reduced by selecting test cases.


Now that we know the techniques used in the implementation of regression testing, let us have a look at the procedure.


The technique for implementing regression testing is the same as for any other type of testing. As part of the testing process, the developer performs the following procedures every time the program undergoes a change and a new release is released:


  • To begin, he runs unit-level regression tests to ensure that the code they've updated is correct, as well as any additional tests they've created to cover new or altered functionality.

  • The modified code is then merged and incorporated into a new build of the application being tested (AUT).

  • Before any further testing, smoke tests are carried out to ensure that the construction is sound.

  • Integration tests are run after the build has been deemed good to ensure that the application's units communicate with one another and with back-end services such as databases.

  • A partial or complete regression is scheduled depending on the size and scope of the published code.

  • The development team is then notified of any defects, if necessary, more regression tests are carried out.


(Also read: What is A/B testing?)


To perform regression testing we need to choose test cases and we should know how to choose the best test cases.


Test Cases to Choose for Regression Testing


The following test scenarios can be used to create effective regression tests:


  • Test scenarios with a high number of flaws,

  • Test scenarios that are difficult to understand,

  • Cases of integration testing, 

  • Test scenarios that cover a product's basic feature, 

  • Functions that are often utilized, 

  • Cases that regularly fail as a test, and 

  • Cases of boundary value tests.


(Must catch: Applications of IT)



Top-3 Regression Testing Tools


The following are the most important tools for regression testing:


  1. Selenium


Selenium is free and open-source software. This software is used to test a web application in an automated manner. Selenium is used for browser-based regression testing. Selenium is used to test web-based applications at the UI level.

The image is showing webpage view of selenium.

Selenium Regression Testing Tool, source: www.selenium.dev

(Related blog: 4 Modules of Selenium Framework)


  1. Ranorex Studio


With the Selenium Web Driver built-in, you can automate regression tests for desktop, web, and mobile apps all in one place. Ranorex Studio comes with a full IDE as well as codeless automation tools.

The banner is the Homepage of Ranorex Studio.                              Homepage of Ranorex Studio, source: www.ranorex.com

  1. Quick Test Professional (QTP)


QTP is a regression and functional testing tool that is automated. It's a keyword-based, data-driven tool. For automation, it made use of the VBScript programming language. 

Depicting the homepage of QTP.

Homepage of QTP, Source: Wikiepedia

The blog ends here, to conclude, I would say presently every industry is employing software in their operations and infrastructure such that they need to ensure that the software is of high quality. One of the primary ways to do this is regression testing incorporating quality testing in industries’ effective workflow.



  • itsolutionsfleek

    Sep 24, 2021

    Wow. What informative content. It will be so helpful for me. I have also written something on this. Please do check it on the link given below and let me know the changes if any. https://www.fleekitsolutions.com/regression-testing-approach-tools/

  • jamesdaniel7306

    Jan 22, 2022

    Utsav, this is a nice writeup on what regression testing is and how it works. In software, a "regression" is a bug in an area of the app or website that was previously working. Regression testing is the most thorough type of software testing and can be done with manual or automated testing. It should be done anytime there’s a new feature or update. This is to ensure that the changes in the code don’t cause issues with existing features. Here are a few insightful blogs on regression testing: https://bit.ly/3FOYJ6P