Retesting is like double-checking that spot to ensure the fix works. It's like proofreading a sentence you've just corrected in your document, ensuring the correction fits perfectly without affecting the rest.

What is the difference between regression testing and retesting?

Retesting focuses on verifying specific identified defects that have been fixed correctly. It involves testing only the defective parts after they have been repaired. In contrast, regression testing ensures that recent changes or fixes have not introduced new bugs into the previously stable software parts. It involves a comprehensive testing of the entire application or its major parts.

When to do retesting and regression testing in software development lifecycle?

Retesting should be performed as soon as a specific defect has been fixed to confirm the effectiveness of the fix. It's a part of the defect lifecycle. Regression testing, however, is generally performed after retesting and before a major release.

Is regression testing only necessary for big projects?

Regression testing is not restricted because of the project type or size. Think of regression testing as a safety net that catches these potential issues, ensuring that your software remains stable and reliable, no matter how big or small your project is.

How frequently should we do regression testing?

It completely depends on the project’s development lifecycle and the rate at which changes are made to the software. In Agile environments, regression testing may be performed at the end of every sprint or before a new release. In more traditional development settings, it might be scheduled at specific milestones. Ideally, it should be performed whenever significant changes are made to the codebase.

How do we automate regression testing?

Repetitive tasks and defined test cases can be automated during the regression testing process. It is a mix of automated and manual testing. Manual testing allows for exploratory testing and discovering issues that automated tests might not catch. However, automating regression tests saves time and resources while enhancing efficiency.

Regression Testing Vs Retesting: Key Differences

Posted On: 1 February 2024

Software development is a journey filled with challenges, and one constant companion on this path is the presence of errors, bugs, and uncertainties. However, what truly separates exceptional software from the rest is how efficiently these challenges are managed and resolved. This is where a well-structured testing plan becomes paramount, and at the heart of this plan lie two essential practices: Regression Testing vs Retesting.

In this blog, we will understand

What is regression testing?
What is retesting?
When Is Retesting and Regression Testing Done?
The Differences
Regression Vs Retesting
Conclusion

What is Regression Testing?

With more businesses rushing to churn out high-end digital applications to remain competent in their key markets, there has been a phenomenal rise in the use of software test automation. It helps companies keep up with the growth without compromising on the quality of the applications they launch to the market.

Studies estimate that globally there will be USD 28.8 billion worth of market size for automation testing by 2024!

The automation testing approach eliminates a lot of effort and cost that often plagues manual testing efforts. It also avoids bias that may occur due to human judgment of scenarios. Automation testing also empowers continuous development and deployment of software in a productized form which is a critical requirement for faster release of digital applications in the market now.

But does this mean the end of the practice of testing manually? The answer is no.

What is Retesting?

Contrary to regression testing, retesting is done to test whether a particular feature or functionality that has been developed, tested, and released is working as expected. It’s generally carried out after significant modifications to the code or software are made.

When running retests, your goal is to determine whether any known bugs have re-emerged or whether new bugs have appeared.

When Is Retesting and Regression Testing Done?

Testing Type	Scenario	Description
Regression Testing	New Feature Implementation	Ensures that the code needed for a new feature functions properly, even after refactoring or removing code.
	Updates and Patches Application	Verifies compatibility of changes with existing software, can be performed before or after installation.
	Release of a New Product	Ensures no unintended consequences are associated with a new release of the product.
Retesting	Bug or Issue Identification	Used to verify that identified bugs or issues no longer exist in the software.
	Problems with Reports	Ensures that issues related to reports are resolved and the reports function correctly.
	Changes in Business Logic	Validates that changes in business logic, such as alterations in report numbers or database fields, do not affect the overall functioning of the software.

Difference Between Retesting and Regression Testing

These are similar-sounding terms but not interchangeable. Retesting ascertains that a specific code fix works as expected.

Regression testing, on the contrary, ensures that the entire system works as designed after changes. Regression tests, as such, have a much wider scope of activity when compared to retesting.

Retesting usually takes place near the time of code development. Contrarily, regression testing is further along the development lifecycle. These tests need more time for execution as compared to retests. Complete regression testing demands testing for all aspects of the system and needs adequate, system-wide monitoring.

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Regression Testing vs Retesting: The Differences

	Regression Testing	Retesting
Automation	Considering that the testing suite expands with the enhancements, the automated regression testing approach seems viable.	Because the motive is to fix the pre-existing areas, automating the methods seems unnecessary and implausible.
Involvement	Regression testing must be a perpetual monitoring process since updates, upgrades, and patches are constantly unearthed to keep up with the dynamic market.	Since retests depend on identifying the bugs in the first place, retesting may or may not be employed in each testing cycle.
Types	Corrective, selective, progressive, partial, unit, retest-all.	No types as such; however, the practice to re-test can differ according to the needs.
Nature	Since it’s perpetual, regression testing is often termed generic testing.	Since its implementation is specific to the identified defective area, it’s often termed planned testing.
Defect Verification	NA	A part of retesting process
Applicability	Fixated on passed test cases.	Fixated on failed test cases.
Priority	Low (exceptions surface during parallel testing)	High
Accuracy	To predetermine test cases, each methodology can’t be implemented with the same approach to ensure consistency.	Since the test strategies are often modified based on earlier findings, there is little chance of repetition.
Example	After adding a new feature, the entire application is tested to ensure existing features still work.	After fixing a specific bug, only the particular feature where the bug was found is retested.

Conclusion

Both practices are vital for delivering high-quality software that meets user expectations and maintains a bug-free environment. Regression testing ensures the overall stability of software by verifying its functionality after changes. While retesting focuses on specific modifications. The choice between them depends on project needs, with automation playing a key role in regression testing.

Geosley Andrades

Director, Product Evangelist at ACCELQ

Geosley is a Test Automation Evangelist and Community builder at ACCELQ. Being passionate about continuous learning, Geosley helps ACCELQ with innovative solutions to transform test automation to be simpler, more reliable, and sustainable for the real world.