Mastering Regression Testing Techniques for a Flawless Application

Published Date

August 20, 2024

Read

7 minutes

Written By

Jui Deshpande

Regression testing is performed after changes are made to an application, including code optimizations, to ensure the functionality remains intact and the application runs smoothly. If any issues are found during regression testing, the source code is debugged to identify and fix the bugs. Once the bugs are fixed, the failed test cases are re-executed to confirm that the issues have been appropriately resolved. One must execute the failed regression test cases again to ensure that the defect is fixed properly.

Techniques to Perform Regression Testing

1. Full Regression

In this technique, we execute all the test cases in the regression suite. Generally, this is done before deploying the code in UAT or production. Executing all the regression test cases at least twice a year is good practice.
Advantages: This technique ensures that we check the entire application thoroughly to identify loopholes. Thus, we reduce the probability of getting issues in the production environment.
Disadvantages: This technique requires considerable time to complete the testing cycle. The time for completion depends upon the number of test cases you have in the regression library.

2. Risk Based Regression

In this technique, we identify the modules impacted by the latest changes. Once the module has been identified, one must select the critical test cases from a business point of view likely to be affected by this change. One should have thorough domain knowledge for identifying test cases. We must locate test cases smartly to ensure that we cover most of the test cases around the area of change. We can reference the Requirement Traceability Matrix (RTM) to ensure all test cases are covered for the changed requirements. Once the test cases have been identified, you can review the selected test cases with a business analyst or other stakeholders.
Once the necessary changes have been deployed in the required environment, the team should start executing the identified impacted test cases.
Advantages: We can complete the testing in fewer days and ensure that the newly added functionality does not impact on the existing functionality. This is an effective technique if one identifies the impacted test cases wisely.
Disadvantages: With this technique, as we need to check the application thoroughly, there is a chance that we might miss defects. We can reduce % of defects by identifying impacted test cases correctly.

3. Priority Based Regression

In this technique, we select high-priority test cases from each module in the application. One can plan to execute higher-priority test cases every week. It will confirm that the main functionality has been fixed due to any recent changes in the application. We can also execute high-priority test cases in case of any urgent deployment in production.
Advantages: We complete the testing in fewer days and can ensure that the newly added functionality does not impact on the high-priority functionality.
Disadvantages: Even if we check the application thoroughly, there is still a 2-3% chance of missing defects. Executing only high-priority test cases is not a good option for regression testing.

Use of Automation for Regression Testing

1. Automation of Regression Suite

We should automate the regression suite as early as possible after releasing the first version of the application. This will help us to reduce regression testing time in upcoming releases.

One can automate the regression suite in phases, as detailed below:

In Phase I of automation, we should plan to automate high-priority test cases. Once these test cases are automated, we can plan to execute them every week or as and when required.
In Phase II of automation, we should plan to automate the test cases that have been identified as impacted test cases quite often. By automating high frequency impacted test cases, we can reduce the execution time during the regression cycle.
In Phase III of automation, we plan to automate all the remaining test cases so that the complete regression suite will be automated.

2. We should integrate an automated regression testing suite with CI/CD tools such as Jenkins and Azure DevOps, promoting a streamlined workflow and continuous testing. We can also leverage automation framework capabilities if they support them.

Execution of Regression Suite

1. Execution of a regression suite can be prioritized using the ways listed below:

Execution of high-priority test cases to ensure that the latest changes do not impact highly sensitive business workflows.
Execute test cases identified during risk-based regression to ensure that the newly updated changes do not impact existing functionality. This will give confidence that all the test cases listed in RTM are executed to ensure the stability of the requirement.
Identify and execute corner scenarios from each module manually if time permits.

2. Execution Using Automation Suite

After Phase I of automation, once the high-priority test cases have been automated, we can plan to execute impacted test cases manually and high-priority test cases using automation. We can schedule nightly execution jobs to get the results the following day. In addition, we can also execute high-priority test cases using automation every week.
Once Phase II of automation is completed, one can plan the execution of high-priority and impacted test cases using automation. This will save time, and the results will be shared with the team as soon as possible.

Maintenance of Regression Suite

One should keep the regression suite current with the latest changes in the application.

Set up a meeting with stakeholders to identify any new regression test cases to be added, per the latest additional functionality in the regression suite.
Sometimes, we need to update existing test cases according to new functionality changes. Each time, one must update the test cases according to the latest changes.
When updating the existing test cases, you must plan to update the automation scripts according to the changes. Also, if you add a new test case to the regression suite and it is a high priority or listed many times under impacted test cases, you must plan to automate the new test case as soon as possible.

Conclusion

Regression testing is like a guard for your application. If you follow regression testing in every sprint cycle or during the release cycle, you will get fewer issues in postproduction deployment. Agile implementation of regression testing plays a crucial role in aligning the existing and updated functionalities, avoiding all possible rework in the future. Automated regression tests significantly reduce the time and effort needed for manual testing. This efficiency allows QA teams to focus on complex testing scenarios and other critical tasks. Regular regression testing ensures that the application adheres to industry standards and compliance requirements, which is essential for maintaining the integrity and security of the product.

About the Author

Jui Deshpande Group Project Manager (Reliability Engineering)

Jui is an experienced QA professional with over 20 years’ experience in testing, test automation and test project management. She specializes in implementing the best QA practices across multiple projects and applications. She enjoys collaborating with quality teams to implement new QA methodologies and automation tools in projects. Jui guides teams of automation engineers and test engineers across multiple projects using different technologies and makes sure all deliverables are delivered with good quality. She also has hands-on experience in testing and test automation frameworks.