Regression Testing is software testing to ensure that a current program or code modification has not adversely impacted existing features. Regression Testing is a full or partial extract of already executed test cases re-executed to confirm that existing functionalities work fine. This testing ensures that new code changes do not affect the existing functionalities. It ensures that the old code works once the latest code modifications are done.
Testers should be clear about “What is regression testing”? Regression testing is a software testing technique that guarantees that an application functions as expected. Regression testing is accountable for the existing features' overall solidity, stability, and functionality. In this article we will have a deep dive of what is Regression testing in software engineering, process, and types with examples. Regression testing requires a thorough understanding of the regression testing processes and individuals should have at least 2-3 years of experience with software testing skills. Enrolling in the Software Testing Certification courses would ensure individuals nourish their skills.
What is Regression Testing, and Why is It Important?
When software is built, it needs constant maintenance. New updates and significant changes are done from time to time to ensure that the software functions optimally. After these important improvements to the software, it will be tested to ascertain that the code still functions properly. The process of rerunning the code to ascertain its functionality is referred to as regression testing.
Regression testing is important because it helps developers to know if the changes done to software have negatively affected how well that software functions. Without regression testing, a developer will not detect defects and or bugs on the newly updated software or ascertain if the new changes that were done to the code altered how well the previously existing code functions.
When to Perform this Test
A regression test should be performed under the following circumstances
- When a new feature has been made to the existing code.
- When patch fixes are added
- When some changes have been made to the configuration of the code
- When the codebase is fixed to solve defects
- When the source code is optimized to increase its effectiveness.
- When there is a problem with the performance
When a bug is detected, trying to fix that one bug can result in the appearance of more bugs, and this spells doom for the software if those are not quickly fixed. Although difficult to carry out, a regression test should be performed as frequently as possible. Doing this ensures that an upgrade does not have damaging effects in the long run.
Types of Regression Testing in Software Engineering
There are various ways to carry out a regression test. These various types of regression testing are:
1. Retest-all Regression Testing
With this approach, a brand-new test is run on the code. It is a very thorough kind of regression testing. It is typically carried out when something appears to have gone wrong. Regression testing of this kind produces more satisfying results, but since it is so thorough, it is also quite expensive to conduct.
2. Corrective Regression Testing
This is a simple form of regression testing. This method is focused on running a regression test even though there was no change in the code. In this type of testing, test cases that have previously been created can be used to execute the test.
3. Selective regression test
This method focuses on picking a subset of cases from a larger collection to examine a certain section of the code that has been impacted. This method aims to analyze the impact of new code on the already existing code.
4. Progressive Regression Testing
Regression testing of this kind is used after making new modifications. In this kind of regression testing, new test cases are used instead of outdated ones. This kind of test guarantees that none of the crucial features from the previous version have been broken in the current one.
5. Partial Regression Testing
In partial regression testing, the existing test cases are mostly utilized to test the effects of a new set of code on an old collection of code. It is employed to confirm that a piece of software still operates as it previously did despite new code additions.
6. Complete Regression Testing
When a code base has undergone numerous modifications, a full regression test is conducted. When extensive system modifications are required to improve the functionality of the code, it is carried out. It primarily occurs when the root code has been modified.
7. Unit Regression Testing
In this type of regression testing, the code is tested as a single unit. This method will require that all existing interactions and dependencies are blocked when the test is running.
The top regression testing tool that can be used are
1. Selenium
Selenium is an open-source tool used for automated web testing. It is the leading web testing tool and can be executed on desktop and mobile devices. By running test Selenium scripts against web browsers like Chrome, Firefox, and Safari, testers can ensure their web app doesn’t break.
Selenium can be used for tests like UI, sanity, and regression. Executing Selenium for regression testing aids developers in finding defects in their web apps before they deliver them to end customers. Strategically, such tests permit developers to change code and introduce new features.
Automating Selenium regression testing allows testers to focus on resolving issues or on more complex types of tests. In addition, automation guarantees tests are executed methodically and efficiently and are not subject to human error.
2. TestComplete
The general process of conducting regression testing in TestComplete is as follows
- Application Testing and debugging.
- Devise a test for elements or features added to the new build.
- Run old and new tests over the latest build.
- Repair and rerun until there are no issues and it is clean.
- New tests are added to test the product for each new build. These tests are then added to the test sequence of the project.
3. Katalon studio
Katalon Studio is an automation solution that sustains functional and regression testing. It helps transform these processes into easy and simple tasks for testers. Katalon Studio provides an all-in-one regression testing tool for your website, web services, and mobile application. It also supports running scripts on multiple devices, browsers, and environments. Test results can be reviewed in comprehensive and customizable reports, i.e., in LOG, HTML, CSV, and PDF formats, and forwarded as email attachments.
4. Rational Functional Tester
IBM Rational Functional Tester is a functional, automated, and regression testing tool. It provides automated functional, regression, GUI, and data-driven testing capabilities. It helps in various applications, including web-based, .Net, Java, Siebel, SAP, terminal emulator-based applications, and PowerBuilder.
5. Micro Focus Unified Functional Testing
Micro Focus Unified Functional Testing (UFT) was earlier known as QuickTest Professional (QTP). It provides functional and regression test automation features for software applications and environments.
UFT helps with keyword and scripting interfaces and features a graphical user interface. It uses the Visual Basic scripting language to specify a test procedure and to influence the objects and controls of the application. UFT allows developers to test all three layers of a program's operations from a single console: the interface, service, and database.
UFT was written by Mercury Interactive and called QuickTest Professional.
6. SoapUI
SoapUI are used for RESTful API and SOAP Web Service testing, Functional Testing, Performance Testing, Interoperability Testing, Regression Testing, and much more. Also, check out the top software testing tools here!
Regression Testing Techniques
The necessity for software regression testing arrives when there is software maintenance, including enhancements, error corrections, optimization, and deletion of current features. These changes can impact the system's functionality. Regression Testing becomes vital in these circumstances.
Source: Javatpoint.com
Regression testing can be accomplished using the following techniques:
1. Retest All
In this method, all test cases are run again to see if any new defects have been introduced by the code modification. The best results are obtained with this procedure, but it can be time- and money-consuming.
2. Regression Test Selection
This method selects certain test cases from the test suite. The whole test suite is not rerun, in contrast to the retesting of all techniques. In this strategy, regression testing test cases are broken down into:
- Reusable test cases that can be used in future regression testing
- Obsolete test cases which cannot be used in future regression tests.
3. Test Case Prioritization
In this technique, test cases are selected on the basis of their priority. A test case's impact on the final product, failure rate, and functionality will determine its priority. The test cases with higher priority are executed before those with lower priority.
4. Hybrid
This is a combination of both regression testing selection and test case priority. Individuals can enroll in KnowledgeHut’s Software Testing Certification Courses and gain expertise if they are looking for a career as a Software tester.
Regression Testing in Software Testing Example
Let's imagine a team of programmers created "App X," an app with the ability to send and receive files between devices. A total of 1000 test cases were used to check the app's initial functionality, and the results were good. The customer who received this product loves it but occasionally requests that the developers add a new feature that would allow users to examine the shared files both before and after sharing them.
The developers then add new codes to the ones that currently exist and retest them using new test cases. The customer receives the app again and subsequently reports that although users may view the files they want to send, they are no longer able to transmit files as they once could. The error was found and corrected. The app was then tested again using both the old and new test cases. The client receives the app back and confirms that it is now in good working order.
In this instance, the developers made changes to the program without running the preceding test case again, and as a result, they are now having trouble getting the app to perform as it did before. All of these issues are avoided through regression testing, and the client's firm won't lose customers as a result.
How to Create an Effective Regression Testing Suite?
Step 1: Prioritizing Regression Test
First, include in your test suite the most important test. These tests are those with top priority. Select these tests based on how much they affect the critical features and thus the overall function of the product.
Defining what should be a high priority is important. After defining what is a high priority, arrange the test according to their priority from those with the highest priority to those of lesser priority. When the test begins, a tester should start with tests with high priority and then move towards those with low priority.
Step 2: Developing Smoke Test
The "smoke test suite" should be the name of the regression suite you create when compiling your critical and high-priority tests. Make sure to complete the smoke test before commencing additional tests to avoid unwarranted shutdowns. This testing should be carried out frequently, usually daily, twice a week, or after a new build. A person should make sure not to test every function with a smoke test but only the high-priority functions. A person can also automate these tests if they choose to.
Step 3: Take Assistance of Manual Testing
Next, you should build a suite for the core functions of the software. A tester may need to perform a manual regression test for some of these functions that are always used and may thus have complex interactions making it difficult to do automated testing on them. One can also decide to combine both manual and automated testing to tackle complex functions.
Step 4: Test The Integration
Next, run a regression test suite that includes important integrations such as APIs, backend messaging, database connections, and data feeds. End-users do not engage with these functions, but they are important in the smooth running of the software.
Step 5: Take Performance into Account
After all is done, run a performance test on your software to ensure that the product runs smoothly. Ensure that with the changes, the software does not become too slow before releasing it into the market.
How to Select a Regression Test Suite?
To select a regression testing suite, some very important standards should be met.
- Test cases that cover critical areas of the application/business
- Test cases that undergo frequent modifications
- Test cases that cover the core functionality of the product
- Test cases that cover areas that easily become unstable when a new feature is added
- Test cases that yield bugs easily
- Test cases that are considered complex.
Step 1: Regression Test Selection
This step requires that a QA puts together all the test cases that they intend to re-execute. Important criteria for selecting test cases have been discussed above.
Step 2: Determine The Time for Executing Test Cases
Determine how much time it would take to run all the test cases for selected features. Determine how much time a test case may take up, especially if the test is done manually.
Step 3: Identify The Test Cases That Can Be Automated
Know what test cases should be automated and which should be done manually. The automated test saves time and is more reliable and also allows a tester to reuse the same script continuously. The test cases to be automated should be kept in a separate group from those that would be tested manually; this ensures that there is no mix-up.
Step 4: Test Case Prioritization
Have the test cases prioritized. The test cases of utmost importance will have top priority and one should execute them first. The priority of a test case is assessed based on its impact on the software's operation and how frequently users interact with it. The structure for priority is as follows
1. Priority 0
Of highest priority. Affects the function of the software greatly.
2. Priority 1
Of moderate priority. Not part of the basic functionality.
3. Priority 2
Of least priority
Step 5: Executing Test Cases
Make use of the appropriate regression testing tools to begin executing the selected test cases. Execute the test cases one after the other using either manual or automated methods.
Regression Testing Best Practices
Regression testing is a dependable and efficient technique to make sure that software works as intended, but the procedure itself can be challenging. The following actions can guarantee the best outcome possible.
A) Prioritization
Always prioritize the most crucial test cases. This is because attempting to execute every test case will consume too much time and will increase costs. Prioritization ensures that the most important functions of software get tested.
B) Automate
Regression testing requires a great deal of automation. Time and money are saved, and it is more effective. Automated testing will free up testers to concentrate more effectively on manual testing, which may be necessary for more complicated test cases.
C) Perform tests continuously
Continuous regression testing increases the likelihood of finding issues and hastening their correction. By doing this, the software is continuously kept in good condition.
D) Update regression pack often
As soon as a new release or software upgrade is finished, test cases are gathered into what is called a regression pack. One should continually update and add new test cases to the existing test cases for the software to maintain good performance. This ensures that when a regression test is done testers would avoid executing test cases for functions that have become obsolete.
Regression Test Plan Template
According to the Oxford dictionary, " a plan is a detailed proposal for doing or achieving something". For regression testing to go smoothly it needs planning. A regression plan template provides a structured means by which important information regarding the regression testing procedures gets documented. The main information of a regression template plan is contained within its Table Of Content (TOC). With a test plan, important information details are not left out and successful regression testing can be achieved.
Sample 1:
Sample 2:
Download Regression Test Plan Template here!
REGRESSION TEST PLAN TEMPLATE: Sample Test Plan (Ecommerce Project) |
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Prepared By: (Names of those who Prepared) (Date) |
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Table Of Contents (Toc) 1.0 Introduction |
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2.0 Objectives And Tasks 2.1 Objectives 2.2 Tasks |
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| 3.0 Scope |
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4.0 Testing Strategy 4.1 Alpha Testing (Unit Testing) 4.2 System And Integration Testing 4.3 Performance And Stress Testing 4.4 User Acceptance Testing 4.5 Batch Testing 4.6 Automated Regression Testing 4.7 Beta Testing 5.0 Hardware Requirements |
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6.0 Environment Requirements 6.1 Main Frame 6.2 Workstation |
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| 7.0 Test Schedule |
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| 8.0 Control Procedures |
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| 9.0 Features To Be Tested |
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| 10.0 Features Not To Be Tested |
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| 11.0 Resources/Roles & Responsibilities |
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| 12.0 Schedules |
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| 13.0 Significantly Impacted Departments (Sids) |
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| 14.0 Dependencies |
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| 15.0 Risks/Assumptions |
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| 16.0 Tools |
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| 17.0 Approvals |
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Advantages and Disadvantages of Regression Testing
Advantages
- Increases the chances of discovering bugs and defects
- Ensures that fixed bugs and defects do not reoccur
- Improves the quality of the software
- Ensures the release of healthy and optimal software products into the market
- Ensures that the existing features in the system remain intact even with constant modifications and upgrades to the existing code.
- Can be automated or performed manually
- Guarantees continuity of business operations
- Helps reduce unnecessary expenses, thus minimizing the cost of the phone too. This is mostly true when automated testing is done.
- With automated testing, one can save both time and money
- Assures that the software is always current and in pace with new developments in technology.
Disadvantages
- If one makes use of manual testing, it will take a lot of work and be very time- and resource-intensive.
- It is a very repetitive process that, over time might have an impact on the agile sprint.
- Does not a particular frequency
- Required even if only the tiniest change is made to the current code.
- With constant modifications and changes to an existing code, over time the test becomes more complicated.
- It can get discouraging for the testers to have to keep running the same test, especially if it is done manually.
Difference Between Regression and Re-testing
Regression testing and retesting both aim to guarantee that a software operates as efficiently as possible. Despite the commonalities that each have, they each go about achieving their objectives differently, thus their differences. Here are some distinctions between regression testing and retesting.
| Regression Testing | Re-testing |
|---|
| The main goal is to ensure that modifications to existing code do not affect the functionality of the software | The primary objective is to ensure that any failed test cases in the final execution function properly after the problem has been resolved. |
| Can be automated or done manually | Always carried out manually |
| Passed test cases can undergo regression testing. It focused both on failed and successful test cases | Only failed test cases undergo Resetting. It is done to ensure that test cases that failed in the last execution are functioning properly and that all bugs are fixed |
| Not done specifically to detect if a bug has been fixed | Done specifically to detect if a bug has been fixed |
| Also known as generic testing | Also known as planned testing |
| Regression testing looks for unanticipated defects which are side effects of modifications made to the existing code | Looks for initial issues in a code |
| If resources are available, it can be done along with retesting. | Is carried out before regression because it is of a higher priority. |
Conclusion
The role of regression testing in the build of a software cannot be overemphasized. If regression testing is ignored after an update, then the chances of a business releasing a bad product and therefore having huge losses increases. To make the process of testing easier, automated testing should be used to save both time and resources.
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