Retesting vs. Regression Testing: Know the Difference

In the dynamic world of software development, constant updates are the key. These updates warrant testing to ensure the much-needed quality assurance. Retesting and regression testing are two fundamental testing methodologies that aid in maintaining software integrity. 

In this article, we will delve into the nuances of these tests, especially regression testing, highlighting its significance, key differences from retesting, methods of calculation, real-world examples, and answering frequently asked questions. 

What Is Regression Testing? 

The fundamental aspect of quality assurance of these software updates is testing. These tests systematically examine software to identify defects, inconsistencies, and potential issues. One of the most vibrantly used testing procedures is Regression.

Regression testing is an important strategy used for most software testing. It helps in the verification of existing functionalities in terms of recent code changes. The aim is to ensure that new modifications or additions to the software do not introduce unintended side effects or bugs that could potentially compromise the system’s performance. This process is essential to maintain the overall integrity of the software while keeping up with the ever-evolving development landscape. 

Regression testing acts as a safety net by rerunning existing test cases to ensure the software’s core functionalities remain unaffected. The primary objective is identifying and rectifying any unintended consequences of code changes before they reach the end users.

Are you wondering what “Regression” means in Tamil? Well, in Tamil, it is rendered as “மீறுவழி” (mīṟuvazhi), referring to the process of moving backward or reverting to a previous state. In the context of software testing, regression testing aims to prevent the software from regressing to a state with defects or issues.

Retesting vs. Regression Testing: The Key Differences

Retesting is used to verify that the defects found in a software system have been fixed correctly. Whereas regression testing is used to verify that the changes made to the software do not have unintended consequences on previously tested functionality.

Regression and Retesting testing are often used interchangeably, but they address distinct aspects of software quality assurance. Retesting involves testing the same functionality or feature that showed a defect to reconfirm that the defect no longer exists. It is primarily focused on confirming that specific defects have been fixed.

On the other hand, regression testing goes a step further. It entails testing not only the modified areas of the code but also the surrounding functionalities to ensure that no new defects or problems have arisen due to the recent changes. While retesting is confined to the immediate vicinity of the reported defects, regression testing casts a wider net to prevent potential issues from occurring due to interactions between different parts of the software. 

In terms of the time of testing, regression testing is performed after any changes that are made to the software, whereas retesting is performed after a defect has been identified and fixed.

Thus, it can safely be said that while both retesting and regression testing are integral components of software quality assurance, they have distinct scopes, purposes, and timing.

How to Calculate Regression

Calculating the extent of regression testing can be challenging. The decision on which test cases should be included depends on factors such as the nature of code changes, the complexity of the application, and the criticality of the features involved. Here are some key steps to consider when calculating regression testing:

• Identification

The first step is identifying the areas where the codes have been changed. This could include new features, bug fixes, or modifications to existing functionalities.

• Selection

Next is to select the relevant test cases based on the modified code that exercises those specific functionalities. One can even include test cases that cover adjacent and dependent features to catch any potential ripple effects.

• Prioritization

Prioritize the selected test cases based on criticality. High-priority test cases should cover essential functionalities, while low-priority test cases can address less critical parts of the software application.

• Automation

To expedite regression testing, consider automating test cases. These can be run quickly and repeatedly, reducing the time and effort required for testing.

• Creation

As your application evolves, build a comprehensive regression test suite that encompasses a wide range of functionalities. This suite should grow with each code change to ensure comprehensive coverage over a period of time.

Examples of Regression Testing in Software Development

To illustrate the significance of regression testing, let us consider a practical example that we all come across. The banking application that we all use allows the transfer of funds between accounts, paying our bills, and viewing transaction histories, among many other features. If the development team decides to add a new feature that enhances the user interface for fund transfers, this will warrant updating of software. However, while implementing this change, they could have inadvertently introduced a bug that affected the transaction history display.

In such a case, regression testing comes into play. The team needs to verify that the newly added feature functions correctly and that the unintended bug does not impact other aspects of the application, such as bill payments or account balances. By performing regression testing, the team detects and rectifies the issues before they reach the end users, thereby maintaining the application’s reliability.

Let us see this with another example. Consider a software product used for managing inventory in a retail shop. A new update software release has introduced improvements to the reporting module, enabling users to generate more detailed sales reports. However, during development, a modification inadvertently causes the system to miscalculate stock levels in certain situations.

In this case, the development team can promptly identify and rectify the miscalculation through regression testing. Moreover, they can validate that the changes made to the reporting module have not negatively impacted other functions of the inventory management system, such as order processing or item tracking.

FAQ: Commonly Asked Questions About Regression Testing

1. What is the difference between retesting and regression testing?

Retesting focuses on verifying that specific defects reported earlier have been successfully fixed. It involves testing the same functionalities to ensure the issues have been resolved. On the other hand, regression testing encompasses testing not only the modified functionalities but also other related features to ensure that new changes have not introduced unintended issues.

2. How frequently should regression testing be performed?

The frequency of regression testing depends on the development cycle, the volume of code changes, and the criticality of the application. In agile development, regression testing is often conducted after each code change or user story iteration. In more traditional development models, it might be performed before major releases or when significant changes accumulate.

3. Can regression testing be automated?

Yes, regression testing can be automated using various testing tools and frameworks. Automated regression tests can be executed quickly and consistently, making them highly efficient for frequent code changes.

4. What happens if regression testing is not performed?

Skipping regression testing can lead to software releases with undetected defects or bugs. These issues might emerge later, causing disruptions, user dissatisfaction, and increased development costs.

5. How does regression testing contribute to software quality assurance?

Regression testing is critical in quality assurance by identifying and addressing unintended consequences of code changes.

6. What are some challenges associated with regression testing?

Some regression testing challenges include selecting the appropriate test cases, managing the growing test suite, dealing with dependencies between functionalities, and maintaining the balance between testing thoroughness and time efficiency.

Conclusion

In the dynamic landscape of software development, ensuring the stability and reliability of applications is vital. Systematically testing regression testing safeguards against unintended consequences of development efforts. Distinct from retesting, which focuses on confirming defect resolutions, regression testing provides a holistic software integrity assessment.

Maintaining software is difficult but mandatory in the fast-paced world of software development. Retesting and regression testing are two indispensable methodologies that ensure the stability and functionality of software applications. Retesting verifies the resolution of previously identified defects, while regression testing validates that recent code changes have not negatively impacted existing functionalities or introduced new issues. Both practices contribute to the overall reliability of the software products and are essential components of the quality assurance process. 

In essence, retesting addresses the past, ensuring that old issues are resolved, while regression testing focuses on the present and future, ensuring that new changes don’t disrupt established functionalities. As the software landscape continues to evolve, embracing both retesting and regression testing will remain pivotal in delivering robust and reliable software solutions to users.