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Retesting vs. Regression Testing

Software testing consists of several different tests, each serving a different purpose. Retesting and regression testing are two types of software testing that are often confused for one another but which serve very different purposes.

Let’s narrow down what each type of test entails and their differences.

What is Retesting?

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Retesting is a type of testing performed to verify that previously failed test cases pass during re-execution. Imagine a scenario in which a test case fails, but the development team resolves the issue. In such a case, the test case is retested to determine whether it has been passed or not.  Retesting takes place after the development team fixes the bugs. It can be defined as a verification activity conducted to ensure fixed software conforms to its specifications.

Retesting is a great way to ensure that your features still work after fixing bugs. You can also use it as an opportunity for you and your QA colleagues, together with developers who test code before releasing new updates or fixes on known vulnerabilities. This way prevents any unexpected issues from occurring during end-users usage of these applications.

What is Regression Testing?

Regression testing is software testing executed to ensure that changes made to the code or particular defect (bug fixes, new features, etc.) have not introduced new bugs or caused any other parts of the program to break.

In other words, it is a process of verifying that a software program still works after it has been changed.

To ensure the software is still working properly after updates or changes, companies often perform regression testing. This type of verification ensures any new features don’t negatively affect other parts used by users (such as existing bugs).

Unlike retesting, which checks if a particular test case now passes, regression testing checks if the software works as expected after changes have been made. So when you alter your application’s code, it’s always good practice to perform regression testing.

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Procedures for Testing

Retesting

To retest software, the tester needs the following:

The tester first analyzes the bug report to understand what went wrong.

When a bug is reported, the test team needs to get all the information about what went wrong to fix this as quickly and efficiently as possible. The team should always look at how they used the system when things went wrong. Then, testers can figure out if they need to push through new tests or re-run old ones until everything passes.

If all fails again, one needs to raise another issue so the team can work on fixing these problems sooner rather than later. Retesting is a manual testing process.

Regression Testing

To perform regression testing, the tester needs the following:

  • Specification or Business Requirements Document
  • Test Cases
  • Test Data
  • Build or code changes

The tester first analyzes the build or code changes to understand what has changed. He/she then checks if a test case for that particular functionality exists. If it does, the tester executes the test case with new test data (if required). If the test case fails, the tester raises a new bug. It is advisable to automate regression tests as they need to be run frequently (usually after every code change).

Now that we know about retesting and regression testing, let’s look at some of the key differences between the two:

Key Difference Between Retesting and Regression Testing   

Testing process

Retesting is mainly performed after the development team has fixed the bug and checks if a particular feature works as expected after fixing that bug. Retesting is an essential tool for developers because it allows them to check if their work has been completed correctly. It also gives users peace of mind knowing that bugs in features are fixed after retesting.

Conversely, a regression test checks if code changes have introduced new bugs and if the entire software application continues to function as expected. Regression tests allow testers and engineers alike confidence when making changes by ensuring none of those adjustments introduce new problems or broken functionality

Cost

Retesting is less expensive, time-consuming, and requires less effort than regression. The lower costs are due to only needing to focus on a failed test case and check if it now passes.

Regression testing involves running the entire suite of test cases to ensure changes made to the code have not introduced new bugs elsewhere in the application. As a result, it is more expensive compared to retesting.

However, automating regression tests would help you save time and money compared to manual regression testing because each new release tends to get more expensive.

Manual vs. Automated Testing

Regression test cases are often automated because these tests build up as the software changes or grows. Automation always complements the regression test process and is one of the most important stable features of any regression test suite.

On the other hand, retesting cannot be automated because of uncertainty, as defect verification falls under retesting and not in regression testing. Therefore, the priority of regression testing is lower than retesting.

Retesting and regression testing often occur within the same testing process and go hand-in-hand. They are both integral in the confirmation testing process. However, they serve different purposes.

Let’s look at the detailed comparison between retesting and regression testing and know when to use which technique for your project.

Comparison Table: Retesting vs. Regression Testing 

Regression Testing vs Retesting

Regression Testing Retesting
Regression testing is done for passed test cases Retesting is done only for failed test cases
Regression testing is done on the entire system or application Retesting is done on specific features or modules
Regression testing cases are derived from the functional specification Retesting test cases that failed in the prior execution is only re-executed
Regression testing is done to check the system as a whole Retesting verifies only those areas which have been affected by the changes made
In regression testing, you can use automation tools for an easier and more efficient process Retesting can be done without any automation tools
You can do regression testing without fixing the bug. You cannot do retesting without fixing the bug
Regression testing ensures that the entire software application works as expected after a code change. Retesting is done to check if a particular feature works as expected after fixing a bug
Regression testing is done to check if updates affected the existing functionality Retesting is mainly done to check functionalities
Regression testing is a validation activity Retesting is a verification activity or defect verification
Regression testing checks if the software works as expected. Retesting checks if the software conforms to its specifications

FAQ’s

How can a Test Case Management System help with retesting or regression testing?

A test case management system, such as AccelaTest, can help with retesting by organizing and storing test cases, as well as tracking which ones have been run. For regression testing, AccelaTest can quickly help identify which test cases need to be run again after code changes.

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What comes first retesting or regression testing?

Retesting is a subset of regression testing, so regression testing should be done first. When changes are observed in the software, regression tests are conducted and then retested upon the release of the new code. Regression tests ensure no new defects are introduced by changes, while retests ensure no existing defects remain.

What is the main purpose of Retesting? 

The main purpose of Retesting is to ensure that a particular test case passes after the development team has fixed a bug. Retesting is usually done manually.

What is retesting testing with examples?

An example of retesting would be if a developer fixes a bug in a website’s login page or feature. The tester would then Retest the login feature to ensure that it now works as expected.

What is regression testing with examples?

An example of regression testing would be if the developers change the code that affects the login feature. The tester would then need to regression test the login feature and other website areas to ensure that no new bugs have been introduced.

Final Verdict

Now, when it comes to Retesting vs. Regression testing, which one should you choose? The answer is that it depends on the situation.

Retesting and Regression testing are essential activities that help ensure the quality of software applications. So, always keep your testing objectives in mind when deciding which one to choose.