Regression Testing: Everything You Need to Know- Approaches, Techniques, Pros and Cons, and E2E Process

Regression testing is a software testing technique that verifies the continued functionality of an application after recent changes to its code or configuration. During this process, previously executed test cases are re-run to confirm that the software still performs as intended and that any modifications have not introduced any new defects or errors.

Why the regression testing required?

Regression testing ensures that a software application performs as expected even after the changes, updates, or enhancements have been made to the code. It plays a crucial role in maintaining the stability and functionality of the existing features.

When the regression testing needs to be performed

1. After making the changes to the codebase
2. After fixing the bugs
3. After upgrading the software
4. After the configuration modification

Pros of Regression Testing:

It helps in detecting defects, Improving the quality of the software, reducing the risk of introducing new defects into the software, Saving time and money by catching the defects early and preventing more serious issues from arising and it can boost the confidence of developers and stakeholders in the software application.

1. It helps to find the defects that might have been introduced in the code during the code fixes or feature creation, making it easier to find.
2. It helps to ensure that the software’s overall quality stays high and that any new features or modifications do not adversely affect the software’s functionality as it currently exists.
3. It helps to keep the user’s trust in the software and in the organization that develops it.
4. It helps in lowering the danger of program failures and related expenses.

Cons of Regression Testing:

Regression testing can be time-consuming, and resource-intensive as require significant amounts of time, effort, and resources, and also involves duplicating efforts as some tests may cover the same functionality that has already been tested in the previous testing cycles

1. It can be time-consuming and expensive if the software is complex or has a number of features.
2. The cost and complexity of the testing process may rise as QA might need specialized testing tools and resources.
3. It might not always catch all the defects, especially if they have to do it with various software components interactions.

Example of Regression Testing

Suppose, a software application has a feature that allows users to upload, edit and delete documents. The feature has been thoroughly tested and is working correctly.

Now, a new version of the software is released that includes a number of changes to the user interface and some underlying code. To ensure that the document upload, editing and delete feature still works correctly, QA needs to perform regression testing to make sure the feature is working fine using the same test cases and data as before. Any defects that are found would be reported and fixed before the software is released to users.

Regression Testing Approaches and Techniques

Here are some regression testing approaches and techniques:

Manual Regression Testing: This involves manually executing test cases that have been previously executed to make sure that existing functionality has not been affected by any of the changes. This approach is time-consuming and can be error-prone, but it is useful for testing specific scenarios and edge cases.

Complete Regression Testing: In this approach, the entire application is retested from scratch to ensure that all the functionalities are working correctly. This approach can take a lot of effort and may not be effective for large and complicated applications.

Selective Regression Testing: In this approach, only the application’s components that are impacted by the fresh changes are evaluated again. This approach can save time and is also suitable for large and complicated applications.

Re-testing: This technique involves re-executing the previously executed test cases to make sure that the software application is still working as expected.

Retest All: In this technique, all test cases are run once more to make sure the new changes/fixes/modifications have no impact on the application’s current features. This method takes a lot of effort and may not be effective for complicated applications.

Regression Test Selection: Using this technique, only the test cases that are affected by the new changes/fixes can be executed. This method is efficient and works well with large applications.

Prioritization: In this technique, the QA needs to prioritize the test cases based on their importance, and the high-priority test cases should be executed first. Prioritization ensures that the critical functionalities of the software application are tested first and also helps to identify defects earlier.

Automated Regression Testing: In this technique, test cases are automated using tools like cypress/selenium/playwright, which makes the process faster and more efficient by providing reports of the passed/failed test cases. This ensures that the same test cases are executed repeatedly and eliminates the possibility of human error for the automated features.

E2E process: How to analayse and perform the regression testing with the below flow

I hope this article helps you in performing regression testing in the software applications

Keep learning :)

Thank you,

Priyanka Madan Lal