Regression testing and retesting are essential methodologies testers employ to ensure software quality. If you’re new to both or aren’t sure when to use which technique, this article should help. We’ll discuss the importance of regression testing in software testing.
Then, we’ll cover some examples of retesting and regression testing and review the critical differences between the two. Hopefully, you’ll come away with a deeper understanding of when and how to employ regression testing vs. retesting.
At first glance, regression testing and retesting seem similar. However, as you examine both, it becomes clear that they serve distinct purposes in software testing. Let’s start by looking at regression testing and how it’s used.
When software goes through code changes, there’s always a risk that the new updates made to one section could adversely impact other components. It’s good practice to put the application through tests that ensure new features, bug fixes, or performance enhancements haven’t introduced new bugs or defects.
Regression testing is a systematic process of checking for potential side effects caused by software modifications. The application should function correctly and perform according to user requirements. Regression testing covers previously built and tested functionality, including critical features and common user scenarios.
Testers run applications through a comprehensive suite of tests that cover all new and modified components potentially impacted by updates. Regression testing is typically integrated into the continuous integration (CI) progress to ensure a software product’s stability. Code changes, new builds, and commits are usually enough to trigger a new round of tests.
Several components must be in place to conduct regression testing effectively, which are covered below.
The size of many software products makes manual regression testing impractical. Automated regression tests reduce testers’ effort to provide coverage to all critical components. They can execute many test cases quickly, which helps teams discover and repair defects early.
Teams automate regression testing to eliminate the potential for human error. Once a testing script is built and executed, testers can reuse it in future regression testing cycles, which cuts down on the time it takes to retest an application. Testers can run more extensive test suites that cover many scenarios if needed.
Test suites are groups of test cases designed to verify software functionality. That allows testers to provide complete coverage to critical and minor application functions. Test suite components include:
This development practice involves developers integrating code changes into a shared repository using tools like GitLab or Jenkins. Performing an integration triggers an automated build and testing process that includes regression tests. Developers use CI to ensure early validation of code changes, which reduces the chances of defects accumulating without getting addressed.
Code coverage measures how extensively code undergoes testing. A high level of coverage indicates that a significant portion of the software has undergone comprehensive testing. Below are some different types of code coverage.
Now that we better understand the practice let’s look at examples of regression testing in real-world scenarios.
A popular online vendor decides to expand the selection of products sold through their e-commerce platform. The features it needs to test include adding new products to a shopping cart and building wish lists containing the items.
First, testers use software regression testing tools to build a regression test suite that covers functions like authenticating users, performing product searches, and processing orders. Once created, testers execute the tests to ensure that each component functions as before the new software changes.
A company introduces a new feature into its content management system (CMS) that allows users to schedule online posts. The testing team must expand their current regression suite to include functions used for the scheduling feature. Once that’s done, the regression testing should confirm no impacts on existing features like media uploads, content editing, and publishing.
A finance company reinforces its website’s security protocols after discovering software vulnerabilities during a routine scan. They want to ensure the application complies with regulatory requirements around protecting user data.
Testers should have a regression suite containing test cases covering essential user functions like account login and transactions. Once the company implements new security protocols, the tests should ensure the changes have not disrupted regular user operations.
While regression testing broadly covers an entire application, retesting targets coverage for previously reported issues. For example, a tester might report that a website drop-down menu fails to fill in any selection options. After the developer fixes it, the tester retests the drop-down menu’s functionality to ensure it works correctly. Retesting is software testing that verifies defects no longer exist and reviews scenarios that failed during a previous testing cycle.
One of the biggest challenges of retesting is finding enough time and resources to conduct different tests. Automation in software testing alleviates much of that pressure.
In some instances, defects occur in places where functionality gets extremely complicated. Testers must set up very detailed test cases to cover those scenarios. That makes execution more difficult, especially when navigating complex integrations or business logic.
If a tester fails to properly set up a test case, that could lead to incorrect verification. A defect might persist in the software and cause problems for end users. The best way to mitigate those issues is by using automated testing software that allows testers to design test cases that visualize how different components interact.
Other issues that testers often run into include:
Below are some examples of how testers use retesting in software testing.
Users have reported an issue with changing the profile picture associated with a mobile app account they created. Once developers implement a fix, testers must execute all functions a user would perform related to that functionality, including logging into their account and successfully updating a profile picture that fits the application’s parameters.
A website displays an error message when users attempt to access an option from the menu. Testers must design cases that cover all menu choices that users might access. Once developers make their repairs, the tester must execute each test case to ensure users can access all menu options successfully without crashing the website.
Let’s look at key factors that outline the difference between regression testing and retesting.
The primary purpose of regression testing is to ensure that new code changes don’t negatively impact existing software functions. Testers look beyond defects to ensure no unintended side effects appear in different parts of the application. In comparison, retesting focuses on specific issues that are sent back to developers for fixes. Testers make sure that the changes made to a single defect produce a successful result.
Regression testing occurs throughout the CI process at predefined intervals. This can include night builds or when a developer makes significant changes and checks them into a repository. Testing can also happen on a scheduled basis to ensure an application’s stability.
Retesting is performed right after a developer fixes a defect. It’s done as needed to confirm the resolution of an issue. The focus is on ensuring users can use website functionality without a problem going forward.
Testers must create and access a comprehensive suite of test cases covering different functionalities. They include edge cases, integration points, various user scenarios, and all critical paths. Regression testing aims to provide broad testing coverage to check for adverse code change impacts. Testers execute different tests, including functional, integration, and system.
Retesting is limited to specific test cases that failed because of defects. Coverage is much narrower because the focus is solely on components impacted by defects. Testers do not introduce new tests for any unrelated areas.
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