Regression Testing Technique

A Regression Testing is a software testing technique, in which it is tested that, whether addition, deletion, or modification in any part of the source code is changing/affecting the functionalities of the software.

Regression testing can be carried out at any point in the software development process. Regression technique is the easiest way to check, how the system will be hampered while modules in part of the software are changed.


Regression testing is also the way of selection of an already existing test case or any part of the test cases. Then, the same test cases are again deployed into the modified software and seen whether all the expected functionalities are meeting.

Below we list some of the requirements for Regression Testing Technique:

  • Whenever a significant modification is done in the software coding.
  • Whenever, there is a doubt that a slight change in the coding statement, may change the entire functionality of the software, which is not at all expected.
  • When defects are corrected in the software, then this testing is very important, because sometime, just removing defects may direct the existing function do perform something else, which is not preferable.
  • When performance issues are fixed, then also Regression Testing is done, to make sure that not even improvising the same code or replacing with the same functions with better efficiency has not made any impact on the output functionality of the software.
  • Whenever, any new feature is added into the software, then this is a compulsory step to perform the regression testing in the software.

Installation Testing

The process to perform Regression Technique

Regression technique may be required to be done at different times. The number of updates or delete or optimize the codes in the software, that many numbers of times, Regression has to be carried out.

Regression Technique can be done with the following steps:

First of all, Test all and see the performance, efficiency, etc. Then modify the codes as per requirements and retest again and then again perform the test. This can be iterated again and again to get the expected output.

Retest entire software:

In this step all the integrated modules, that is the complete software is retested entirely. Though this process is extremely expensive and resources consuming, but this step has to be carried out. Now doing this, one trick is always followed.

That is, using only a part of the test case and not the entire test case, which makes it efficient, faster and easy. This is done with the logic that, if some related codes on a particular inter-linked module are modified, then all the other modules which are not anyways connected to it, can be avoided.

In this case, the part of the test case which is relevant to the expected functionality is only chosen and then the test case is applied to retest it.

In this case, the test cases are categorized into two different types. One is reusable and the other one is Outdated or Obsolete.


In this step, we see the most frequently used test case or the part of the test case which is used again and again then prioritize it.

This helps us to reduce the redundancy of using similar test cases.

The next step is to see how we select the test case for regression testing. Selecting a test case for the regression test case is not an easy task. To do this, we have to see test cases which have more defects.

The next step is to see which are the test cases which are related to the core and the most expected functionality of the product. All integration test cases are to be seen, as well as, all complex test cases are to be studied.

Similarly, we have to the boundary value test case and also have to study the successful test cases and failed test cases also.

Some Regressions Testing Tools and why to use tools?

When there is a frequent modification of the software, regression test may be needed to be done more frequently. In this case, the test case may differ a little or even it may remain the same. Therefore, to perform the regression testing again and again manually, more cost and time will be required.

Therefore, we may automate the system, that the test cases are automatically modified and fed during all the iterations of regression testing. So, various tools have been developed from time to time, as per the requirements in the software development industry:

Some are listed below:

  • Selenium: Selenium is an open source tool and is mainly used for web applications and web browsers. This tool finds its uses in different browser-based regression testing.
  • QuickTestProfessional: This tool is from HP and is an automated tool (software) which is used to automate the functional and regression test case deployment into the software to test it. This tool uses Visual Basic Script for its automation. It is a data-driven and also a keyword-based tool.
  • Rational Functional Tester: This tool is from IBM, and is based on Java. This tool is also used to automate test cases of software applications. This was mainly used for carrying out regression testing and can also be used as an integration module with Rational Test Manager.

Recovery Testing

ReTesting Vs Regression Testing:

  • Retesting is done to check whether the test cases which failed earlier is now getting executed in the software after the defects have been fixed. On the other hand, in regression testing, it is checked whether the software is performing well and normal after new modules and features are added into the software.
  • Retesting does not require a new test case to be made, as the old test cases itself can be implemented and checked whether now it is performing well. On the other hand, in regression testing, developing new test cases may be required, as new functionalities are added into the software.
  • Retesting is mainly carried out based on the defects which are cause the test cases to fail. On the other hand, regression testing is based on testing an area of a software which may require testing, because of the addition of new functionalities.
  • Retesting can be carried out with the test case which failed earlier. On the other hand, in regression testing, we have to apply the test case which passed earlier if the modifications made are not significant or large.
  • Retesting may not require adding new software or hardware resources. On the other hand, in regression testing, if the modifications made are significant, then there may be requirements for adding new resources.

Interface Testing


Regression Testing is a software testing type in which it is tested whether the addition of new features has induced any error in the software. Addition of new features can induce different kinds of error such as security of the software may be compromised, performance may be degraded. etc.

Regression testing can be done alongside with sanity testing or retesting, but must be carried after any kind of new features is added to the software.

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