Regression testing - types and examples

Regression testing is a type of software testing that is performed to ensure that new code changes or updates do not introduce new bugs or break existing functionality in a software application. It is crucial to perform regression testing after every code change, bug fix, or new feature implementation to verify that the existing features and functionalities are still working as expected.

 

There are several subtypes of regression testing:

 

1. Unit Regression Testing: This type of regression testing focuses on testing individual units or components of the application, such as functions, methods, or classes, to ensure that they continue to work correctly after code changes.

 

2. Partial Regression Testing: In this type of testing, only a subset of the application's features or functionalities are tested. It is typically used when the code changes are localized, and the tester has a good understanding of which areas of the application might be affected.

 

3. Complete Regression Testing: This is a comprehensive form of regression testing where the entire application is tested to verify that all features and functionalities are working correctly after code changes. It is often time-consuming and resource-intensive, but it provides the highest level of confidence in the application's stability.

 

4. User Interface (UI) Regression Testing: This type of regression testing focuses on testing the user interface of the application, including verifying that the UI elements, layouts, and functionality are working correctly after code changes.

 

5. Database Regression Testing: This type of testing involves verifying that the application's database functionality, such as data retrieval, insertion, updates, and deletions, is working correctly after code changes.

 

6. Integration Regression Testing: This type of testing focuses on testing the integration points between different components or modules of the application to ensure that they continue to work correctly together after code changes.

 

7. Performance Regression Testing: This type of testing aims to verify that the application's performance, such as response times, throughput, and resource utilization, has not degraded after code changes.

Examples:

Sure, here are examples for each subtype of regression testing:

 

1. Unit Regression Testing:

   Example: After modifying the code for a sorting algorithm function, you run unit tests to ensure that the function still correctly sorts arrays or lists of different sizes and with varying data types.

 

2. Partial Regression Testing:

   Example: After adding a new feature to the user registration module of a web application, you perform regression testing on the user registration flow and related functionalities, such as email verification and account activation.

 

3. Complete Regression Testing:

   Example: Before releasing a major version update for a word processing application, you perform complete regression testing to verify that all features, including document creation, editing, formatting, printing, and file management, are working as expected.

 

4. User Interface (UI) Regression Testing:

   Example: After redesigning the layout of a mobile app's main screen, you perform UI regression testing to ensure that buttons, menus, and other UI elements are displayed correctly and functioning as intended on various screen sizes and resolutions.

 

5. Database Regression Testing:

   Example: After modifying the database schema or updating the database management system version, you perform database regression testing to verify that data retrieval, insertion, updates, and deletions are working correctly for different types of queries and transactions.

 

6. Integration Regression Testing:

   Example: After integrating a new payment gateway into an e-commerce application, you perform integration regression testing to ensure that the application can still communicate and exchange data properly with other integrated systems, such as inventory management and order fulfillment.

 

7. Performance Regression Testing:

   Example: After optimizing the caching mechanism in a high-traffic web application, you perform performance regression testing to verify that the application's response times and throughput have not degraded and that it can handle the expected load without performance issues.

 

8. Security Regression Testing:

   Example: After patching a security vulnerability in a web application's authentication system, you perform security regression testing to ensure that the patch has not introduced new security vulnerabilities and that existing security measures, such as input validation and encryption, are still functioning correctly.

 

These examples demonstrate how regression testing subtypes are applied to different aspects of an application to ensure that code changes do not introduce new issues or break existing functionality, providing confidence in the application's stability and reliability.

 

8. Security Regression Testing: This type of testing involves testing the application's security features and vulnerabilities to ensure that code changes have not introduced new security risks or compromised existing security measures.

 

Regression testing is an essential practice in software development to ensure the stability and reliability of applications after code changes. The choice of regression testing subtype depends on the scope, complexity, and risk associated with the code changes, as well as the available resources and time constraints.