How many types of Regression Testing are there and their Impact

The fast-paced progression of digital technologies and market dynamics means businesses have to keep their software products updated at all times. Consequently, they have introduced changes to such products to make them more appealing, functional, secure, navigable, and compatible. However, these changes can affect software products in myriad ways with regard to their performance, functionality, usability, security, and others. Furthermore, a live software product on the market may be rendered unusable after it hits a bug. To remedy the situation, the software code containing the bug was backdated, analyzed, and fixed. The process, however, may not always be smooth sailing for the development team as the software product may encounter post-remediation shocks. Hence, to prevent such an eventuality, the testing team performs what is called end-to-end regression software testing.

What is regression software testing?

Regression testing is a black-box testing technique that performs repeated tests on a modified software application to ascertain if the modified code has disrupted anything that was functioning before. A change to the software application can be done in various ways, namely, adding new functionality, enhancing existing functionality, integrating APIs, fixing bugs, enhancing the interface, or adding patches, among others. There is a belief among a section of developers that they insist on testing the essential functionalities only during any regression software testing post making a code change. No matter how practical and time-saving the thought may appear, it can do real damage later on. This is due to the fact that any code changes can throw up nasty surprises for the end-users. To put it bluntly, a seemingly simple and irrelevant modification can lead to the breaking down of an existing functionality or module. So, QA regression testing is critical to validating the functioning of a software application after modifying the code.

What are the types of regression testing?

End-to-end regression testing is not a one-size-fits-all kind of thing and comprises several types:

1. Corrective regression testing: This testing type is carried out when no changes are made to the product’s specifications. And the existing test cases are more than enough to perform the specific test. The test analyzes the impact of the changed code on the existing code by using a subset of the already available test cases. This helps to reduce the cost and effort of retesting.
2. Unit regression testing: Performed as part of the unit testing phase, this type of regression testing checks the software code as a single unit. Here, only a focused regression testing strategy is used without considering dependencies that are outside the coding unit and complex interactions.
3. Partial regression testing: In this type of testing, the new code is allowed to interact with specific parts of the existing code to determine whether the system works in silos as expected.
4. Complete regression testing: This type of testing is conducted in modules where the code changes with regard to other modules are not defined. It offers a comprehensive view of the product that has undergone changes and allows developers and testers to address any unforeseen issues. It certifies whether or not the new build has remained static for some time, similar to final software regression testing.
5. Selective regression testing: In this type of testing, a selective subset of the existing test cases is utilized to reduce the cost and effort that are involved in retesting. It involves re-running a test unit to verify the changes in variables and functions.

#6 Progressive regression testing: This type of automated regression testing is performed when specification changes are made to the application. It ensures the new version does not negatively impact the existing features of the software application.

#7 Retest-all regression testing: This type of testing can be a tedious and time-consuming exercise. In this type of QA regression testing, the entire software product, including its features and functionalities, is tested comprehensively by reusing all the test cases. This is done even when code changes have not been made to a major part of the software product. This type of testing should, at best, be avoided when an insignificant code change is made to the product.

Conclusion

As customers demand better functionalities in an existing software application or product, there is a critical need to conduct regression software testing. However, with prioritization, selection, and minimization, the size of the test cases can be reduced while retaining the value of testing.