Maria Homann
Learn about the main differences between retesting and regression testing in this blog, where we explain the two types of testing and show a side-by-side comparison.
Software testing consists of a number of different types of tests. These can easily be confused due to their resemblance and overlapping purposes.
The concepts of retesting and regression testing are often confused within the field of test automation. They sound alike, and they have similarities too.
The main difference is that regression testing is designed to test for bugs you don't expect to be there. Retesting is designed to test for bugs you do expect to be there.
There's more to it than that though, so let's go into further detail to clarify the meaning of these concepts.
Table of contents
When is retesting and regression testing done?
Regression testing vs. retesting: key differences
Example of retesting and regression testing
Elevating your retesting and regression testing strategy
What is regression testing?
The verb regress means to return to a former state or condition. In software, this usually isn’t considered a good thing.
That is why software developers test for regressions, hence the term regression testing.
The point of regression testing is to ensure that new updates or features added to software haven't broken any previously released updates or features.
This type of testing involves rerunning a set of test cases on the modified application to detect any unintended side effects caused by new developments, updates, or bug fixes.
To perform regression testing you typically have a regression suite – a series of test cases set up to test these older features.
There’s good reason to automate regression testing because these tests build up as the software changes or grows, and become infeasible to handle manually.
In sum, regression testing safeguards software against new bugs.
For further detail and examples of regression testing, check out the following articles:
What is retesting?
Retesting, also known as confirmation testing, is a targeted testing approach.
Instead of being designed to search through all the previous updates and features of the software to find unforeseen defects and bugs, retesting is designed to test specific defects that you’ve already detected (typically during your regression testing).
The process involves re-running the test cases that initially failed, but this time on the corrected code, to ensure the issues have been resolved. The process concludes with verifying test results, updating defect statuses, and documenting the entire process for quality assurance and record-keeping.
In other words, while regression testing is about searching for defects, retesting is about fixing specific defects that you’ve already found.
In sum, retesting is about ensuring bug fixes work as intended.
When Is retesting and regression testing done?
Besides the differences in retesting and regression testing purpose and scope, there’s also a difference in when these two types of tests are performed:
When is regression testing done?
Regression testing is conducted at various stages of the development cycle, particularly:
- After any code change: Whenever modifications are made to the codebase, whether it's adding new features, fixing bugs, or optimizing existing code, regression testing is performed. This ensures that the new changes do not adversely affect the existing functionalities.
- Before major releases: Prior to a major product release, comprehensive regression testing is recommended. This helps in identifying any last-minute issues that could impact the user experience or software performance.
- After integration of components: In projects where different modules or components are developed separately and then integrated, regression testing is critical. It ensures that the integrated components work seamlessly together.
- In Continuous Integration environments: In CI/CD pipelines, regression testing can be automated and run as part of the continuous integration process. This allows teams to identify and address integration issues as soon as they arise.
When is retesting done?
Retesting is performed after a defect has been identified and a corresponding fix has been implemented. The main timeline for retesting is as follows:
- After bug fixes: Once developers have addressed the bugs identified during initial testing phases, retesting is carried out. It is a verification process to ensure that the specific issues have been resolved.
- Before regression testing: Retesting is usually done before regression testing. The reason is to confirm that the defect fixes are successful and have not introduced new bugs that could affect the upcoming regression testing phase.
- Throughout the development cycle: Retesting can occur multiple times throughout the development cycle, especially in agile environments where changes and fixes are frequent. Each time a bug is fixed, retesting is necessary to ensure the fix is effective.
Regression testing vs. retesting: key differences
Here’s a side-by-side comparison overview of the key differences:
|
Regression Testing |
Retesting |
|
|
Purpose |
To ensure that new code changes have not disrupted any existing functionalities. |
To confirm that specific issues have been resolved. |
|
Scope |
Involves testing a general area of the software. |
Involves testing a specific feature of the software. |
|
Focus |
Is a broad and comprehensive approach to identifying any new bugs introduced by recent changes. |
Is a more narrow approach focused on verifying the fixes of specific bugs. |
|
Test case selection |
A broader set of test cases is chosen, often including those unrelated to recent changes, to ensure overall software health. |
The test cases are selected based on the bugs previously found. |
|
Fit for automation |
Is ideal for automation as the testing suite will grow with time as the software evolves. |
Is not ideal for automation as the case for testing changes each time. |
|
Role |
Should always be a part of the testing process and performed each time code is changed and a software update is about to be released. |
Is sometimes a part of the testing process, specifically if a defect or bug is found in the code. |
|
Timing |
Is often conducted repeatedly, especially after major code changes, before a release, or after integration of new features. |
Is conducted after defects are fixed but before the software moves forward in the development cycle. |
Example of retesting and regression testing
Let's delve into an example involving a retailer's e-commerce platform, showcasing the critical roles both testing methods play in the software development lifecycle:
- The tester discovers an issue where customers are unable to add items to their shopping cart via the ‘Quick Add’ functionality shown in the image below.
- After identifying and documenting this critical bug, the issue is handed over to the development team for a fix.
- Once the developers address the problem and update the system, the tester retests the shopping cart functionality to ensure that items can now be successfully added to the cart. They also run an automated set of regression tests to ensure that the fix hasn't inadvertently affected other website features.
- This focused retesting confirms that the specific problem is resolved and the e-commerce site operates as intended for customers.
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Elevating your retesting and regression testing strategy
While retesting and regression testing serve different purposes, their combined use is crucial for achieving and maintaining high software quality. Retesting ensures that known defects are effectively addressed, while regression testing guards against the introduction of new errors, ensuring that software enhancements do not compromise existing functionality.
Incorporating both testing strategies into the software development lifecycle enables teams to catch and correct issues early and often. This not only improves the quality and reliability of the software but also enhances user satisfaction by delivering a product that meets or exceeds expectations.
To ensure optimal use of time and resources, regression testing should be considered as a candidate for automation.
Learn much more about automated regression testing in our webinar on automated regression testing. Or, check out our whitepaper: Regression Testing in Agile Teams.
