Software regression testing should be performed and taken up as soon as the programmer adds new functionality to an application.
This is because of the dependency between the newly added and previous functionality that is critical for the software to function according to the requirements defined.
Following are the types of regression testing:
1.Selective regression testing: The impact that the newly added piece of code has made to the existing application software is analyzed by this testing method.
A subset is used of the already existing test case. Through this, the cost involved will further be reduced for retesting and thus a new test case can be constructed from scratch.
2.Progressive regression testing: It offers a series of benefits but, is considered to be a more complex process. According to the need, new test cases are developed in this testing method.
When there are a few changes that a product has gone through, then progressive regression testing can run properly.
It is also used when new test scenarios are developed.Based on the necessity, new test cases are designed.
3.Complete regression testing: This testing method is performed when there are a lot of changes being implemented to the existing code.
It is also used when the root code of the software has a major change in it. Unexpected issues can be ably tackled and resolved and the final test can be carried out before the application is offered to the user.
Many organizations use this testing method because it is able to identify unexpected bugs in considerably less amount of time.
4.Partial regression testing: Certain related modules are selected that might have been affected by any changes made in the code.Codes are added to an application for specific reasons by using this testing method.
So, when such new codes have been added up to the existing code, then testers will start performing partial regression testing.
5.Unit regression testing: The aim of this testing method is to deliver a useful unit of code that can in turn enhance the value of the application.
Whenever a unit is done with the necessary code changes, all the previous positive test scenarios are again run by the tester.Because a single unit of the code is focused upon and conducted in isolation.
Most of the dependencies and interactions are obstructed by the tester when this test is all set to run.The test outcome is evaluated by the testing team.
In an agile environment, software testing needs to be taken up with each sprint and the quality assurance testers should make sure that new changes do not affect the existing functionality of the application.
Moreover, in agile scenarios with iterative changes, there are more frequent build cycles and continuous changes are added to the application. This sort of frequent change makes software regression testing mandatory in agile.
Thus, for successful regression testing in agile, the testing team should follow an effective regression testing strategy and build the regression testing suite from the onset of software product development.