Regression testing is type of testing carried out to ensure that changes made in the fixes or any enhancement changes are not impacting the previously working functionality.
When any modification or changes are done to the application or even when any small change is done to the code then it can bring unexpected issues. Along with the new changes it becomes very important to test whether the existing functionality is intact or not. This can be achieved by doing the regression testing.
It is executed after enhancement or defect fixes in the software or its environment. It can be difficult to determine how much re-testing is needed, especially near the end of the development cycle.
This type of testing typically carried out by testing specialist peoples. The automated testing methods are the best and safe option to carry out the Regression testing.
The purpose of the regression testing is to find the bugs which may get introduced accidentally because of the new changes or modification.
During confirmation testing the defect got fixed and that part of the application started working as intended. But there might be a possibility that the fix may have introduced or uncovered a different defect elsewhere in the software. The way to detect these ‘unexpected side-effects’ of fixes is to do regression testing.
This also ensures that the bugs found earlier are NOT creatable.
During regression testing the test cases are prioritized depending upon the changes done to the feature or module in the application. The feature or module where the changes or modification is done that entire feature is taken into priority for testing.
This testing becomes very important when there are continuous modifications or enhancements done in the application or product. These changes or enhancements should NOT introduce new issues in the existing tested code.
This helps in maintaining the quality of the product along with the new changes in the application.
Usually the regression testing is done by automation tools because in order to fix the defect the same test is carried out again and again and it will be very tedious and time consuming to do it manually.
In the market there are many free as well as free (open source) software testing tools are available. In the larger software development project the Regression testing is commonly used.
Some of the most commonly used regression testing tools list:
- Regression Tester
- Rational Functional Tester
- AdventNet QEngine
It is a verification method & mainly done in system testing but it applicable to all levels of software testing (Unit testing, Integration testing, System testing and Acceptance testing.)
Good Regression tester need to aware of what all features to be focus on changes in the software application.
“The main aim of regression testing to make sure that changed component is not impacting the unchanged part of the component”.
For Example there are three Modules in the Project named Admin Module, Personal Information, and Employment Module and suppose bug occurs in the Admin Module like on Admin Module existing User is not able to login with valid login credentials so this is the bug.
Now Testing team sends the above – mentioned Bug to the Development team to fix it and when development team fixes the Bug and hand over to Testing team than testing team checks that fixed bug does not affect the remaining functionality of the other modules (PI, Employment) and also the functionality of the same module (Admin) so this is known as the process of regression testing done by Software Testers.
In the Software regression testing, tester has to do only the execution of previously executed test cases & compare the result with previously test execution result. If there is not conflict between results then we can say that the regression testing is passed.
In this type of testing new test cases are not created but previously created test suite is executed to find regression defects.
How to define the scope of regression testing?
The scope of testing is based on the how large fixes or enhancements of features. If this is impacting in the larger area of the application then scope will increase proportionally & it requires the deep testing of application including relevant test cases execution. But to analyze this tester should get the correct inputs from developer to decide the scope.
But if you are testing GUI applications the doing regression testing is very difficult. If the changes made in the GUI then all test cases written will not reused. In case if the project is big then it is very hectic work to update the GUI test cases. You have to write it again different test case for updated GUI once again.
Advantages of Regression testing:
- It helps us to make sure that any changes like bug fixes or any enhancements to the module or application have not impacted the existing tested code.
- It ensures that the bugs found earlier are NOT creatable.
- Regression testing can be done by using the automation tools
- It helps in improving the quality of the product.
Disadvantages of Regression testing:
- If regression testing is done without using automated tools then it can be very tedious and time consuming because here we execute the same set of test cases again and again.
- Regression test is required even when a very small change is done in the code because this small modification can bring unexpected issues in the existing functionality.