What is Regression Testing?

Regression testing is one of the testing methods. In regression testing, we will re-run the functional and non-functional tests of existing software. Where it will ensure that the recently applied code changes to the existing software do not effects existing functionalities.

Regression testing

Regression means-testing old code and this testing may be a complete or partial execution of existing test cases. Where this testing helps to prevent the unintended effects of any updates on current applications. Here both the existing code and newly added code will have their functionalities uninterrupted.

In regression testing we re-run test cases continuously using an automation tool, as running test cases manually is very difficult and time-consuming. Here the testing involves verifying the bugs and fixing them without disturbing the existing ones.

When to perform regression testing?

When an existing software application is needs modification, then there is the necessity of performing regression testing. If any release taking more than the expected time, then regression If testing is performed on daily basis. Or in case of weekly releases after functional testing regression testing is scheduled.

We know that retesting means repeating the test cases. There can be various reasons behind retesting, below are some cases of retesting.

  • If any defect is fixed in the application.

Imagine that there are certain buttons in your application, and one of them is not responding. The developer analyzes the code and fixes it, after which a tester will test the button functionality. Here the tester is rerunning the test cases.

  • After applying any extension or change to the application

While giving login if we want to disable “remember the password option”.

  • To add any new functionality in the application

Suppose login to one application is possible using a Gmail account, and to add any other login option.

  • After fixing any performance issue

Reducing homepage loading time to 2 sec from 5 sec.

  • To change the existing environment

If changing the database environment from Oracle to MySql

How to perform regression testing?

Re-testing is necessary when software application maintenance performs optimization, enhancement, defect fixing, and deleting existing features. Know the process of performing regression testing from the below content.

1.Retest All

Re-testing is one of the methods to perform this testing. Wher tester re-runs all the test cases after any modification in the application. If any defect or bug is identified during re-test it should be fixed, and re-test all after the fix to verify the functionality.

Retest all is a time consuming and costly process.

2.Regression Test Selection

Re-test means to re-run the entire test case suite, which is a very expensive and time-consuming process. But in the Regression Test selection, the tester selects test cases to run. Generally, test cases are categorized into two types one is re-usable test cases and the other is obsolete test cases. Test cases that are useful for future regressions are re-usable and which cannot be used are obsolete types.

3.Prioritization of Test cases

Here test cases are given some priority considering their criticality, business impact, and functionalities. Test cases with the highest priority are executed first always. Prioritization of Test Cases optimizes the entire testing functionality.

How to select Test Cases?

In a software testing analysis of finding the reason behind a number of bugs appearance. It says that fixing bugs at the last minute is the major cause. Hence, selecting the appropriate test cases plays a vital role here. There are some methods to choose test cases appropriately they are:

  • Select complex Test cases
  • The boundary value test cases
  • Test cases with frequent defects
  • Test cases that analyze core functionalities
  • Bunch of success test cases
  • Bunch of failed test cases
  • Integration test cases
  • Test cases whose functionalities  at top users view
  • Test cases whose functionality undergoes frequent changes

 Regression Testing Tools

It is necessary to perform regression testing every time the software undergoes changes in it.  If the number of changes is high then, the testing part becomes time-consuming and expensive. Hence, it is a wiser choice to choose an automation tool to perform testing every time. Here are some important automation tools to automate this testing.

Selenium is an open-source automation tool, which can be used for browser-based regression testing.

HP’s Quick Test Professional(QTP) is a data-driven and keyword-based automation tool. This can automate the test cases of both functional testing and automation testing, It uses VBScript.

IBM’s Java tool RFT is another automation tool that automates test cases of software applications.


Regression testing is the best method to save the existing functionalities of software even after introducing new changes. Choosing an appropriate automation testing tool can decrease time and expenses. A survey says that in the banking sector regression testing helps to fix bugs at a faster rate. Which is saving 60% of the time in fixing bugs and 40% expenses in performing testing.

Hope the article was helpful and also refer to more software technology related blogs to learn more.

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