What is Regression Testing? (With examples)
May 13, 2023
What is regression testing?
Regression testing is a type of software testing that is performed to verify that a previously tested software/application or product performs as intended even after it has been modified, updated, or enhanced or even if the system has gone through a change.
The primary purpose of regression testing is to ensure that any changes or modifications made to the software/application do not affect or disrupt the existing functionalities and features of the software. The process of regression testing involves re-executing previously executed test cases and analyzing the outcomes of the test cases to see if any new issues have arisen.
A simple example of regression testing
Regression testing is a type of software testing that focuses on ensuring that changes made to an application or system have not affected its pre-existing features or functionality.
Here is a simple example of regression testing:
Let's say you are a software developer for an e-commerce website. Your team just implemented a new feature that allows users to save items to a wishlist. Before this change, users could only add items to their shopping cart.
To perform regression testing, you would need to run a series of tests to ensure that the new wishlist feature did not break any existing functionality on the website. For example, you might test that users can still add items to their shopping cart, place orders, and search for products without any issues.
If any issues are found during regression testing, the development team can address them before releasing the updated version of the website.
When should we do regression testing?
Regression testing is a type of testing that is performed to ensure that changes made to a software application do not introduce new defects or break existing functionality. It involves re-execution of test cases that have been previously executed to verify that the changes made do not cause any adverse effects on the software.
Here's a simple example of regression testing: Let’s say you have developed a software application that has a form with a “Submit” button. You have performed initial testing and verified that when a user fills in the form and clicks the “Submit” button, the data gets saved to the database correctly. A few weeks later, you have added a new feature to the application that changes the color and font of the form inputs. In this case, you would need to perform regression testing on the form to verify that the “Submit” button still works correctly after the new changes.
Regression testing should be done in the following cases:
1. When new functionality is added to the software
2. When there are changes to the existing functionality
3. When fixes are made to previously identified defects
4. When the underlying infrastructure or platform of the software changes
5. When the data used by the software changes
Whats the process of regression testing?
Here's a simple example of regression testing:
Let's say you have a website that allows users to create accounts, log in, and make purchases. After several months of usage, you realize that the registration process is too long and confusing for users. You decide to make some changes to streamline the process. However, before implementing these changes, you want to make sure that they do not break any of the existing functionality of the website.
To do this, you would perform regression testing. You would set up a test environment, where you would run the existing test scenarios to verify that the changes you made to the registration process do not affect the ability of users to log in or make purchases. You would also add new test cases to validate the changes to the registration process.
Regression testing should be performed whenever there are changes made to the software application, such as bug fixes, new features, or enhancements to existing features. It ensures that the quality of the software remains high and that any changes made do not affect the existing functionality of the software.
The process of regression testing typically involves the following steps:
1. Identify the test cases that will be affected by the changes.
2. Prepare the test environment by setting up the necessary hardware, software, and data.
3. Rerun the selected test cases on the modified code.
4. Compare the results of the previous test runs with the new test runs.
5. Analyze any failures or inconsistencies and investigate the root cause.
6. Update the test cases and test environment as needed.
7. Repeat the process until all the test cases pass and the quality of the software is validated.
How to select test cases for regression testing?
There are several approaches for selecting test cases for regression testing, depending on the nature of the changes made to the software. Here are some common methods:
1. Re-run all existing test cases: This is the most comprehensive approach, where all existing test cases are re-run after every change to the software. While this approach ensures that all possible bugs are caught, it can be time-consuming and often unnecessary.
2. Select high-priority test cases: Another approach is to focus on the high-priority test cases that cover critical functionality and features that are most likely to be affected by the changes.
3. Select test cases based on impacted areas: A more targeted approach is to identify the areas of the software that are impacted by the changes and select test cases that are most relevant to those areas.
4. Use risk-based approach: This approach involves analyzing the risk associated with the changes made to the software and selecting test cases based on the level of risk. Test cases that cover high-risk areas are given priority.
5. Use automation: Automation can be used to run test cases automatically, reducing the time and effort required for regression testing. Automated test cases can be selected based on relevant parameters, such as their coverage of critical functionality and impacted areas.
How to build your regression test suite?
Building a regression test suite is important because it helps detect and prevent issues that may arise when making changes or updates to your software. It ensures stability, saves time and costs by catching defects early, boosts confidence in releases, enables efficient automated testing, aids in maintenance and refactoring, and helps meet compliance requirements.
Building a regression test suite involves the following steps:
1. Identify the application areas that are critical to the business and have a high impact on the end-users.
2. Understand the functionalities of the application and identify the scenarios that need to be tested.
3. Identify key test cases that cover important functionality and scenarios. Use existing test cases or create new ones.
4. Determine the priority of the test cases based on their impact on the application and end-users.
5. Group the test cases into logical test suites based on their functionality or priority.
6. Automate the test cases that are repetitive and require extensive effort to be tested manually.
7. Execute the test cases on a regular basis to ensure that the application functionalities are not affected by any changes or enhancements.
8. Update the test suite regularly based on the changes in the application or business requirements.
It is important to maintain the regression test suite to ensure that it is relevant and up to date. A well-designed regression test suite can help to improve the quality and reliability of the application.
Tools for regression testing
There are several tools available for regression testing. Some of them are:
1. Selenium: An open-source automated testing tool used to test web applications.
2. Appium: An open-source tool used to automate testing of both Android and iOS mobile applications.
3. TestComplete: A commercial testing tool used for automated regression testing of desktop, web, and mobile applications.
4. Apache JMeter: An open-source tool used for performance testing and regression testing of web applications.
5. Ranorex: A commercial testing tool used for automated regression testing of desktop, web, and mobile applications.
6. HP QuickTest Professional (QTP): A commercial testing tool used for automated regression testing of desktop, web, and mobile applications.
7. Telerik Test Studio: A commercial testing tool used for automated regression testing of web, desktop, and mobile applications.
8. SoapUI: An open-source tool used for functional and regression testing of web services.
9. Parasoft SOAtest: A commercial testing tool used for automated regression testing of web services.
10. IBM Rational Functional Tester: A commercial testing tool used for automated regression testing of desktop and web applications.
Can regression testing be performed manually?
Regression testing can be performed manually by executing the test cases that are identified as part of the regression test suite. However, manual regression testing can be time-consuming and prone to human errors. Therefore, it is recommended to use automation tools for regression testing to increase efficiency and accuracy.
Advantages of regression testing
Advantages of Regression Testing include:
1. Ensures quality: Regression testing enhances the quality of software by ensuring that the changes made recently, have not impacted the existing features of the software.
2. Saves costs: Any defects in the software that are identified during regression testing can be fixed or resolved at an early stage, thus saving time and money in the long run.
3. Increases efficiency: Regression testing helps to catch any issues early and fix them quickly, allowing the development team to work more efficiently.
4. Builds confidence: By regularly performing regression testing, the development team can be more confident that the software is working as intended and any new features or changes are not impacting existing functionality.
5. Supports continuous improvement: By incorporating regression testing into the development process, organizations can continuously improve the quality of their software and ensure customer satisfaction.
Disadvantages of regression testing
While regression testing offers numerous benefits, there are also some potential disadvantages to consider:
Time-Consuming: Regression testing can be time-consuming, especially if the test suite is extensive. Running the tests and analyzing the results may take a significant amount of time, which can delay the overall development process.
Resource Intensive: Regression testing often requires a dedicated set of resources, such as test environments, hardware, and personnel, which can increase the cost and complexity of testing efforts.
Test Suite Maintenance: As software evolves and changes over time, maintaining and updating the regression test suite becomes necessary. This involves reviewing and modifying existing tests or adding new ones, which requires effort and resources.
Test Case Prioritization: With a large regression test suite, it can be challenging to prioritize which tests to run in limited timeframes. This may result in less critical tests being skipped, potentially leaving room for undetected issues.
False Positives and Negatives: Regression testing may produce false positives (indicating a problem when there isn't one) or false negatives (failing to detect an actual problem). Dealing with false results can be time-consuming and may lead to wasted effort investigating non-existent issues or missing actual defects.
Limited Scope: Regression testing primarily focuses on retesting existing functionality and may not adequately cover new features or components. This limitation can lead to a false sense of security if new code paths are not thoroughly tested.
Over-Reliance on Test Automation: While test automation can increase efficiency and accuracy, relying solely on automated regression tests may overlook certain types of issues that require manual exploration or human intuition.
Maintenance Overhead: As the software evolves, tests need to be updated to reflect changes in functionality. Maintaining the test suite and aligning it with the current software version can become a complex and ongoing task.
It's important to weigh these disadvantages against the benefits and consider the specific context of your software development process to determine the most effective approach to regression testing.
Types of regression testing
There are different types of regression testing, few of them are:
1. Unit Regression Testing: This type of regression testing is performed at the unit or module level. It verifies whether changes made in one module or unit have any negative impact on the entire system or not. The objective here is to test the individual units or modules that have been modified to ensure that the desired functionality or the old behavior is not affected.
2. Functional Regression Testing: This type of regression testing verifies the functionality of the entire system after making changes in the code. It checks if old features still work after adding new features or making changes in existing features.
3. UI Regression Testing: This type of regression testing focuses on changes in the user interfaces of applications. It checks whether the GUI elements, such as buttons, tabs, text boxes, etc., are functioning as expected after a change.
4. Performance Regression Testing: Performance regression testing focuses on the changes made in the software that may impact its performance. It ensures that the changes made in the code have not impacted the system's performance and it still executes at a satisfactory speed.
5. Security Regression Testing: This type of regression testing is performed to ensure the system's security features after it has been modified. This will ensure that the changes made to the software have not created any security vulnerabilities that could put the system at risk.
Regression test plan template
Here's an example of a regression test plan template:
- Purpose of the document
- Scope of the document
2. Test Environment
- Hardware requirements
- Software requirements
3. Test Strategy
- Strategy for selecting test cases
- Entry criteria for regression testing
- Test results evaluation
- Exit criteria for regression testing
4. Test Schedule
- Test results submission
- Bug tracking and reporting
5. Test Cases
- Test case ID
- Test procedure
- Test data
- Expected results
- Actual results
6. Test Scripts
- Script name
- Script procedure
- Script data
- Expected results
- Actual results
7. Defect Tracking
- Defect ID
8. Risks and Contingencies
- Risks associated with regression testing
- Contingency plan for identified risks
Difference between regression testing and re-testing
Regression testing and re-testing are two terms that are often used in software testing. Although they sound similar, they are in fact quite different. Here are some key differences between regression testing and re-testing:
- Regression testing: It is a type of testing that is performed to check if changes or updates in the software have affected the existing functionality of the software.
- Re-testing: It is a type of testing that is performed to check if defects found during a previous testing cycle have been fixed.
- Regression testing: It is performed to ensure that changes or updates in the software have not negatively impacted the existing functionalities of the software.
- Re-testing: It is performed to ensure that defects found during a previous testing cycle have been fixed and no new defects have been introduced.
- Regression testing: It is performed after changes or updates are made to the software.
- Re-testing: It is performed after defects have been reported and fixed.
- Regression testing: It includes a comprehensive set of test cases to test the existing functionalities of the software.
- Re-testing: It includes only the test cases related to the defects that were reported.
- Regression testing: It covers a broader range of functionalities across the entire software.
- Re-testing: It covers a narrower range of functionalities related to the defective areas.
In summary, regression testing is performed to check if changes or updates in the software have affected the existing functionalities of the software, while re-testing is performed to check if defects found during a previous testing cycle have been fixed. Regression testing covers a broader range of functionalities, while re-testing covers a narrower range of functionalities.
Difference between sanity testing and regression testing?
Sanity testing and regression testing are two different testing techniques with distinct objectives. The main differences between them are:
The objective of sanity testing is to check whether the bugs have been fixed, and the system is ready for detailed testing. On the other hand, the objective of regression testing is to ensure that the recent changes made in the software do not affect the existing functionalities.
Sanity testing is performed when a new build is released, and the software undergoes minor changes. Regression testing is performed after major changes in the software application, such as the addition of new features.
3. Depth of testing:
Sanity testing is a quick and shallow test conducted to ensure the basic sanity of the application. Regression testing is a comprehensive test involving multiple test suites and test cases.
Sanity testing covers a small part of the application, whereas regression testing covers the entire application.
Sanity testing is usually conducted more frequently than regression testing since it is a quick test. In contrast, regression testing is conducted less frequently because it is a more extensive and time-consuming process.
6. Test Case Selection:
Sanity testing requires only a subset of test cases that cover the most critical functionalities of the application. In contrast, regression testing requires a more comprehensive set of test cases that cover all the critical and non-critical functionalities of the application.
Overall, the primary difference between sanity testing and regression testing is that sanity testing helps determine whether the software application is suitable for further testing, while regression testing ensures that the changes made to the application do not affect its existing functionalities.
Difference between smoke testing and regression testing?
Smoke testing and regression testing are two types of software testing that differ in their purposes and scope. Here are the key differences between them:
1. Purpose: The purpose of smoke testing is to quickly determine whether the most critical functions or features of an application are working as expected, while the purpose of regression testing is to ensure that previously working functionality still works after changes or updates have been made.
2. Scope: Smoke testing is a subset of regression testing and involves selecting a limited set of test cases to verify the basic functionality of an application, while regression testing involves testing the entire application or substantial parts of it.
3. Timing: Smoke testing is typically done at the beginning of the testing process to reveal major defects early on, while regression testing is done after changes have been made to ensure that they did not inadvertently introduce new defects.
4. Frequency: Smoke testing is typically done prior to every build or release to ensure that the basic functionality of the application has not been affected, while regression testing is performed after major changes or periodically to ensure that the application is still working as expected.
In summary, smoke testing is a quick and focused test to evaluate basic functionality, while regression testing is a thorough test to ensure that the entire application is still functioning after changes have been made.
Difference between regression testing and development testing?
Regression testing is performed to ensure that changes made to the software or application have not affected the existing functionalities of the system. Development testing, on the other hand, is a type of testing that is performed during the development phase of the software or application to identify and fix defects before releasing it to the testing phase.
The primary difference between regression testing and development testing is the purpose they serve. Regression testing primarily focuses on ensuring that changes do not affect existing functionality, whereas development testing focuses on identifying any new defects during the development phase. Additionally, regression testing is usually performed after the development phase while development testing is performed during the development phase.
In summary, regression testing is performed to ensure that changes made to existing functionalities do not affect them while development testing is performed to identify and fix defects during the development phase.
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