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Among the various testing methodologies, retesting and regression testing are two essential techniques that serve distinct purposes in ensuring the reliability of software products. In this article, we will examine the differences between retesting and regression testing to understand their unique roles in the software testing process.
What is regression testing?
In simple terms, regression testing is like double-checking your favorite recipe each time you tweak an ingredient. When you make changes or additions to your cooking method, you want to ensure that the dish still tastes as delicious as before. Similarly, regression testing in software involves retesting the entire application to ensure that recent changes or updates haven’t unintentionally “spoiled” any existing features, ensuring the software still works as expected. It’s a way to catch and fix any unexpected issues that might pop up after making modifications to the code.
This type of testing is usually performed:
- Whenever developers add, modify, or remove new code;
- After fixing bugs to ensure the changes haven’t introduced new issues;
- Following updates to the operating system, browsers, or third-party tools;
- To verify that performance enhancements do not degrade other functionalities.
As software evolves with updates, bug fixes, or new features, regression testing acts as a quality assurance mechanism, providing confidence that the software remains stable and functions as intended throughout its lifecycle.
Regression testing is essential for several reasons:
- Even minor changes can unintentionally introduce new bugs or issues in the software system. By conducting regression tests, QA’s can catch these regressions early on, preventing them from escalating into more severe problems that could impact the user experience.
- The risk of introducing defects increases as software evolves through multiple iterations and updates. Regression testing helps maintain the integrity of the software by ensuring that new features do not break existing functionalities that were previously working as intended.
- Regression testing assures stakeholders, including clients and end-users, that the software performs reliably even after updates. It helps build trust in the product and enhances its quality, leading to higher customer satisfaction and retention.
What is retesting?
The development team typically performs retesting after making the necessary changes to address the reported defects. It is crucial to conduct retesting promptly to validate the fixes’ effectiveness and prevent any delay in the software delivery process.
For example, imagine you have a digital note-taking app; some users reported a problem where they couldn’t save their notes. In the initial testing, the testing team found the issue and reported it. The developers then looked at the app’s code and fixed the problem. In the retesting phase, testers focus specifically on the saving functionality. They perform various tests, like creating new notes, editing existing ones, and saving them to make sure the reported issue is resolved. The goal is to ensure that users can save their notes without any problems after the fix. This process of retesting helps guarantee that the specific problem users face is fixed, contributing to the reliability of the note-taking app for all users.
The key difference between retesting and regression testing
While retesting and regression testing are both important, they have different purposes, scopes, focuses, and priorities. Let’s take a closer look at the key differences between retesting and regression testing to understand the two processes better:
Focus
As mentioned, retesting focuses on verifying that specific defects identified in earlier test cycles have been fixed correctly. It involves executing test cases related to the fixed bugs to ensure their satisfactory resolution. On the other hand, regression testing focuses on ensuring that new code changes have not adversely impacted existing functionalities. It involves running test cases beyond the fixed defects to check for unintended side effects.
Scope
Retesting has a narrower scope compared to regression testing. It typically covers test cases related to specific defects or areas of the software that have undergone modifications. Regression testing has a broader scope as it involves running a comprehensive set of test cases across the application to detect any unforeseen issues resulting from recent code changes.
Timing
Regression testing is conducted throughout the software development lifecycle, with iterations after each code change to verify that the application remains stable and functions correctly. On the other hand, testers typically perform retesting after fixing reported defects and before releasing the software. It occurs in the later stages of testing to confirm bug resolutions.
Test Cases
Retesting focuses on executing a subset of test cases that are related to the fixed bugs. It aims to validate the specific scenarios that previously failed. In contrast, regression testing involves running a more extensive set of test cases that cover both modified and unaffected areas of the software to ensure overall system functionality.
Priority
The priority of retesting is higher than regression testing since it directly impacts the resolution of reported defects. Once a bug is fixed, retesting ensures that it has been effectively addressed before moving forward. Regression testing, while essential, may have a lower immediate priority as it aims to prevent future issues and maintain overall software quality.
Execution time
Retesting is usually quicker and less time-consuming compared to regression testing. Since retesting focuses on verifying specific defects that have been fixed, it allows for more efficient use of time and resources, as testers can concentrate on validating the specific areas of concern.
Regression testing is more comprehensive and time-intensive. It involves running a full suite of test cases, including both new and existing tests, to ensure the stability of the software across multiple iterations. Due to its broad scope, regression testing can be lengthy, especially in complex software systems where changes can have far-reaching implications.
Automation
Automation plays a significant role in both regression testing and retesting processes. Automated testing tools can expedite the execution of test cases, improve test coverage, and enhance the overall efficiency of the testing cycle.
However, it may be more suitable to conduct retesting manually. It is especially true when the test case involves subjective judgment, exploration of multiple scenarios, or validation of changes in the user interface. Furthermore, setting up automated testing can require significant effort, which may not be justified for small or infrequent tests.
Regression testing, on the other hand, is a process that checks if any new changes made to the software create new issues. It involves running a large set of test cases. Automating these tests saves time and resources, as they can be repeated without manual effort. It also helps get quicker feedback on the impact of changes, making it easier to make decisions during development.
Expert Opinion
Regression testing and retesting are two essential concepts that testers encounter almost every day. Despite their similar names, it’s crucial to understand that they are distinct types of testing, and one cannot be substituted for the other. Retesting involves verifying the correction of specific errors, ensuring their successful resolution. In contrast, regression testing ensures that recent code changes have not adversely affected existing functional capabilities. While retesting focuses on addressing specific issues, regression testing guarantees the system’s overall stability after modifications. Together, these methodologies contribute to comprehensive software quality assurance, addressing both targeted error correction and broader system integrity.
QA Engineer at SoftTeco
Svetlana Khaduskina
Retesting vs. regression testing: a comprehensive comparison
Here’s a comprehensive comparison table between regression testing and retesting.
| Aspect | Regression testing | Retesting |
|---|---|---|
| Purpose | Ensures overall software stability post changes or updates. | Validates the resolution of specific known defects. |
| Scope | Encompasses a broad range of functionalities beyond changes. | Limited to areas associated with resolved defects. |
| Timing | Conducted whenever changes occur, regardless of defect status. | Performed post-resolution of specific defects. |
| Focus | Takes a holistic view, checking for unintended consequences. | Targets specific defects and verifies their fixes. |
| Test cases | Requires a comprehensive suite covering various functionalities. | Involves using the same test cases that were used for reporting the defect. |
| Execution time | May take longer as it covers a broader range of functionalities. | Typically quicker due to a narrower focus. |
| Priority | Can be done in parallel with retesting, overall has a lower priority. | Has a higher priority. |
| Automation | Can be fully automated. | Better done manually. |
Conclusion
While retesting and regression testing share similarities in re-executing test cases, they serve distinct purposes in the software testing process. Both approaches are essential for ensuring software applications’ quality, reliability, and functionality. Therefore, understanding their differences is important for effective test planning and execution.
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