Regression Testing: Types, Techniques, Benefits, Limitations And Best Practices

What Is Regression Testing?

Regression testing is a process in which computer programs are tested in order to ensure that the application or software still works and there are no negative effects on their performance or functionality with the introduction of new changes. 

Regression testing is a common part of the process of software development. In larger organizations, regression testing is performed by specialists in code testing. Generally, the applications or software are updates or some new changes are introduced in order to improve its performance so in regression testing the old test cases which are used in testing the previous version of the software are tested in the new version again to ensure that the old performance and capabilities still work. 

Regression testing is generally carried out by repeatedly implementing the bits of the code to make sure that the constant modification in code doesn't impact the software’s functionality. 

Some software developer believes that there is no need for testing every time there is a new modification in the software until some complications or errors arise in its performance or functionality.

So in simple words, Regression testing is just Re-testing of the software to ensure that any new changes introduced in the software won't affect other functionalities. There are three types of Regression Testing:

Types of regression testing

The types of regression testing and many more things about regression testing will be discussed in length later in this article.

Why Is Regression Testing Needed?

The main aim of conducting a regression testing is to make sure that no bugs or defects occur after new changes and there is no negative impact on performance and functionality due to the new modification in the app. So the using regression testing we can identify the new bugs that are occurring due to new changes and the negative changes in functionality. 

Regression testing is beneficial for a number of reasons such as:

1. With regression testing, the errors and bugs can be identified easily and early which will ensure better performance of the software after new changes. Due to early bug identification, the cost is also reduced because if the bug is identified later a lot of resources need to be used in order to fix it. 

2. When regression testing is performed there will be a greater chance for a bug to be detected which occurred due to the introduction of new changes in the software. 

3. Regression testing will be helpful in identifying the unwanted side effects which are caused due to the change in the operating environment because there can be some problem with the code of the software in the new operating environment.

4. Regression testing is found to be helpful in maintaining the excellent quality of the product. Because after every new change, the regression testing detects all the bugs and side effects and they can be fixed easily so the software keeps on growing better without any side effects thus maintaining an excellent quality of the product. 

5. Regression testing is highly beneficial when changes are continuously introduced in the application of the software. This type of situation is common in a large organization where frequent changes are required in the software for good performance and functionality. 

In simple words, regression testing is needed to ensure the continuous growth of the application or the software without any bugs or side effects. Regression testing is needed to uncover all software regressions effectively and easily. Software regression is a term used in quality assurance. It refers to a bug which can cause issues in the performance and functionality of the software. 

There are mainly 3 types of regression testing namely local, remote, and unmasked. The local and remote are the new bugs which are created due to the changes which are introduced in the system. While unmasked is the bugs that already existed but their effect is seen only after new changes.

When To Perform Regression Testing?

We have already discussed why we need regression testing and from what section we can say regression testing should be performed anywhere a company or an organization can afford it. 

But if we talk about the practicality of that it is far from possible to maintain and design a large set of test cases for regression testing. So it is very important for a company or an organization to determine the new test for the software and how it can be designed. For a perfect and defect-free software regression testing should be performed after any new change introduced to the software. 

Regression testing can also be performed whenever a bug or defect has been found and fixed. But this will be costly too that’s why the frequency of performing regression testing is different for different projects. 

In most cases like in a project of a large organization regression testing is implemented on a scheduled basis like daily, weekly, monthly or other time periods depending on the organization and need of regression testing in the project. 

Regression testing will help in detecting every bug and side effect possible in the software after the introduction of every new change so if regression testing can be performed frequently then more bugs and side effects can be identified and fixed and the product with be more stable and it will maintain its excellent quality. Holding quite a few advantages there are certain disadvantages as well associated with the regression testing. 

The implementation of regression testing is based mainly on automation tools and the tests performed in regression testing are automated functional tests, it holds a possibility that these kind of tests are unstable and volatile which means it requires a good amount of hands-on time or personal intervention from the developers or the member of the quality assurance team. 

The member of the quality assurance team or the developers who are babysitting the automated tests in regression testing needs to confirm the results and the performance which is a drawback as manual labour will be required every time regression testing is implemented. 

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For the automated tests also we need to make a representative sample of tests which will cover the larger collection of all possible and theoretical values. In most of cases, testing with the representative sample is enough as it will cover all the variation and it will save a lot of time than doing regression testing with all possible values.

Types Of Regression Testing

We are already aware of what is regression testing, why we need it, and when it is appropriate to implement. We know that regression testing is performed to check whether the performance of functionality is not affected in a negative way after some new changes are introduced and to identify the bugs due to the changes. 

There are three main categories of regression testing which are based on factors like the types of change introduced and the type of bug which is fixed. 

1. Unit Regression Testing: Unit regression testing is executed during the phase of unit testing. As the name suggests, in-unit regression testing the codes are tested like a single unit. This type of testing has a very focused and narrow approach, where the complex dependencies and interactions that are outside the unit of the code which is in question are blocked temporarily. 

2. Partial Regression testing: After the process of impact analysis the partial regression testing is performed. In partial regression testing, the coding unit which is newly added is allowed to interact with the parts of the code which is already in use or the pre-existing code unit. This is done to ensure that even after modifying the code the functions of the system are working properly as intended. 

3. Complete Regression testing: The complete regression is mostly carried out when there are many changes introduced to the already existing code. It is also used often when the modification in the code or the updates in the software affects the roots or the core of the software due to which a complete or a full system testing is required. 

Complete regression testing provides a comprehensive view of your whole system and it will detect and throw out any problem which is left unseen. The final regression testing is performed to ensure that the newly added code has not been changed for a period of time. After testing and fixing the final version is given to all the end-users. 

Regression Testing Techniques

Mainly there are 5 types of Regression testing techniques. Each of the techniques is applicable for different purposes. Some technique requires fewer resources while some require a lot of resources but that technique will provide the result with greater details. 

The type of technique used in regression testing varies from project to project and from organization to organization. Some organization prefers to use a particular regression testing technique in all their projects. The 5 main categories of regression testing methods are:

Corrective Regression testing 

It is used when no changes are introduced in the current application or software or product specifications. In this case, we can use the test cases which have already been created to perform the testing. 

Progressive Regression testing

This technique of regression testing is used in situations when new changes are introduced in the software’s specification and new test cases need to be designed to perform the desired tests. The progressive regression testing works very effectively when certain changes are introduced in the software’s specification and when new test cases are designed. 

In this technique, a part of the test cases is taken from the prevailing test cases and used which reduces the cost and effort involved in designing all the new test cases. 

Selective Regression Testing 

This technique of regression testing is used to analyze the effects of the newly added code which is introduced in the software to the already existing code in the software. In order to reduce the retesting efforts and cost involved in selective regression testing, we use a part of the current experiments. 

In this technique, a test case is re-executed if any new change is introduced in any module or part of the software or application like factors, capacities and so on. In selective regression testing, the condition between the experiment and the elements covered by the program are very difficult to determine. 

Retest-all regression testing 

As the name suggests this technique of regression testing involves reusing all the test cases and also testing all the possible aspects of the product or software even when a new change is introduced in the software or not. 

This technique is time-consuming and very tedious. This is very expensive as it requires a huge amount of resources because we test all the aspects of the software and all the tests in the existing test bucked have to be re-executed. 

The retest-all regression testing is not advised to use when only a small change is introduced in the software or the product. 

Complete Regression Testing 

We have already discussed this in the types of regression testing. The complete regression testing is used more often when multiple changes are introduced in the software and it is also used in the case when the changes made in the software affect the root or the core of the software. 

This is beneficial as it helps in identifying the unseen problems. After the testing is complete the final software or the product is provided to the end-users. 

How To Do Regression Testing

The activity of software maintenance includes error corrections, deletion, enhancements, and optimization of exiting features. These modifications and new changes can cause some defects in the system. Hence regression testing is required. 

We have already seen the techniques which can be employed in regression testing but there are things we need to take care of while performing regression testing. You can follow the sequence of steps which is given below to understand how to do regression testing:

Smoke or Sanity test

First, you need to perform an initial smoke or sanity test. This test is mainly done to check the stability of the system. The smoke or the sanity test is done to ensure that the normal condition is maintained in the system so that the system will work according to our requirements. In this test, bugs and defects are not identified rather its main aim is to make sure whether the system is stable or not before moving forward with the rest of the testing process.

Requirement Analysis

In many cases when a user or a tester reports a bug it is because of some last-minute alterations. Therefore, the customer’s requirement should be assessed thoroughly and test cases should be designed in such a way that the core feature or the root of the software doesn’t undergo any change or the core remains intact. The modification and addition requirement should also be assessed carefully. 

Criteria to select the test cases

There are many test cases which are designed for performing regression testing. The Sanity test cases are the test cases which check the basic functionality of your software and the sanity test cases are the most important test cases for the development team as well as customers. 

The test cases which are related to ordinary setup are checked on priority. The execution of the test case which is designed for performing regression testing is done as the life cycle of software progresses on the basis of need and bandwidth. In cases of integration test cases that are highly important, a set of regression test cases is needed when integration testing is been performed. 

Care must be taken when performing integration testing as a sudden change is able to break the integration between multiple modules. 

Selection of Test cases

The test cases can be selected after prioritization for the execution. Test cases are selected on the basis of the area in which frequent defects are found and on the basis of the features of your software or application and the criticality of those features. 

In order to reduce the regression of the test suite, the test cases should be selected on the basis of the prioritization. 

Benefits Of Regression Testing
Benefits of regression testing


After learning the need and techniques of regression testing we can see the most obvious benefit of regression testing which is that the testing makes the application or the software bug and defect-free. 

Some of the benefits of Regression testing are:

Thorough symptom coverage

Using regression testing every little bug or defect can be detected. This can be done if regression testing is performed for every little change that has been introduced in the software and some techniques like complete regression testing and retest-all regression testing some problems which remain unobserved can also be detected. Therefore, regression testing has huge coverage of symptom identification. 

Test documentation

Regression testing requires thorough documentation. This is because those documents will become the primary source of communication between the development team and quality assurance team about some important matters like what was the problem found in testing and what are the things that are done to fix those problems and what things are done in order to verify that the fix is done correctly and many such questions. Therefore, the test documentation in regression testing is very helpful. 

Builds confidence

Since the regression testing is done after the introduction of new changes in the software so after the results if no bug is found then it creates a sense of accomplishment and builds confidence in the development team of the software because the changes that they made are working as expected and their hard work paid off in a good way. 

Quick action

There are times when a dysfunctionality in software is very serious and that issue needs to be fixed right away. In this case, Automated Regression testing allows the organization to made sudden changes and provide it to its customers. 

In simple terms, regression testing is beneficial because it always promotes the improvement in the quality of the software or the product. It is beneficial in order to make sure that the issues that are already detected and then fixed cannot be created again. And one of the main benefits is that it ensures that by introducing some new changes the core part of the program remain intact which means the modification doesn't affect the core of the software. 

Regression Testing Best Practices

Any process be it testing or any industrial process or any process in the world if best practices are followed then the result will be very effective and the process will be very efficient. To make your regression testing process very effective you should choose the suitable technique for doing regression testing and follow the sequence of steps mentioned above carefully and along with all this, there are some best practices which you should be followed to make your result as bug-free as possible. 

Use a Test Management Tool

Every process needs to be tracked otherwise you will not get the result that you were looking for, so in regression testing, usage of a test management tool is recommended to track all the tests that are performed. You should also keep track of all the historical records of the performance of your software over time. You should find a test management tool which is fairly easy to use and highly sufficient. 

Maintain a schedule

Maintaining and following a particular schedule throughout the process will lead to an excellent result. Same should be done while performing regression testing. Choose a timetable which you can follow all through the software development life cycle so that things will be always on track. 

Evaluate test prioritization 

Before performing tests in regression testing you should prioritize those regression test in a way which will be more effective for your project. The tests on the top of your priority list should be given more importance than the rest of the others because it will have the most impact on your test results. 

Break down and categorize tests 

When a bigger task is broken down into smaller pieces than it becomes relatively easy to finish. A similar methodology should be applied in regression testing too. Break down your test in smaller pieces so it will be easier to evaluate and understand them. 

After breaking down your tests categorize them according to small and big tests, the smaller tests should be given more priority as their execution and sorting are much easier than the big tests. 

Consider customer risk 

The effects of test cases and regression tests on customers and the organization should be considered. Therefore, during the prioritization and development of regression tests keep in mind the customer and organization’s needs and requirements. The test cases should be designed considering the needs of the customer. 

Perform exploratory testing

Before launching the app or giving the app to the customers the software should be tested thoroughly and should be examined whether the function and performance are working as expected. Therefore, before giving the application or software to the customer, the exploratory test should be performed to ensure the functionality and performance of the software. 

Automated Regression Testing

As the name suggests the Automated regression testing is a technique of software testing that utilizes the tools and techniques which are computer-based for testing the software or application when new changes are introduced in the software. 

It is just the automated process of regression testing which includes all the workflow, scripts, plans, and other processes that fall under regression testing. 

Some initial research is required in the software testing criterion, the test plans involved in regression testing, and the changes that are introduced in the software for automated regression testing. 

The automated regression testing seeks to identify non-functional and functional bugs, error, and defects which occur in the software which is tested after the introduction of new changes. 

Basically, automated regression testing incorporates all the methodology of normal regression testing which we have learned earlier in this article, the only difference is that in automated regression testing some scripts and other things are automated so that no manual labor is required for testing and the effective cost is also reduced. 

In automated regression testing, testing for all possible supporting devices is also done which compliments with the core software. Testing for the core logic and the workflow of the software is also included in automated regression testing so that the functionality and performance of the software can be tested. 

In automated regression testing, the testing processes are automated in order to verify whether the software is working properly or not after the introduction of new changes. The main benefit of automated regression testing is that the cost and efforts involved in the testing process are reduced effectively when automated regression testing is employed as there it is less tedious and less time consuming, and it doesn’t need the presence of any personal hands.

Another benefit of automated regression testing is that we can automate the test scripts so that we don’t have to write long and repetitive test scripts for every test cycle. 

The Limitations of Automation

There are limitations to everything as nothing is perfect in this world. The main disadvantage of automation, when employed in regression testing, is that it gives a false sense of quality. This is because the automated scripts will look for only those defects which it has been programmed and some unseen defects can remain unobserved. 

The automation is also not reliable as the automation tests can fail because of many factors such as bugs and some error might occur when long test scripts are executed. The automation tools need to be regularly upgraded which takes up both time and resources. 

The automated scripts can take a lot of time to prepare which is dependent on the complexity of the project. 

Differences: Retest vs. Regression Testing
retest regression


We have seen both the types of testing, retesting, and regression testing. But before jumping into the detailed difference between both types of testing let’s look into the basic definition of both types of testing. 

In retesting, after identification and fixing of bug the software is testing again (retested) to ensure that the bug which is detected is removed successfully or not. While in regression testing, the software is tested when new changes are introduced in the software to make sure that there is no effect on other parts of the software due to the new modifications. Some of the differences between Regression testing and retesting are as follows:

1. Regression testing is the type of testing which is intended to make sure that new modification doesn’t affect the rest of the software. This means when certain changes are made in the software like module enhancement or bug fix then due to these modifications the unchanged part of the software remains unaffected. while retesting is done in order to ensure that the test cases which have failed in the previous testing due to some defect or bug are executing successfully after the corresponding bug or defect is fixed. 

2. Regression testing is not performed on the basis of the specificity of a bug fix. It is planned on a specific area or sometimes full regression testing is performed. While retesting is performed on the basis of defect fixes. 

3. In regression testing, the test cases which have successfully passed early can also be included. We can use it to check the software’s functionality to ensure that the parts of the software which have not been modified remain unaffected. While in retesting, the test cases which have failed earlier can be included. We can consider it in order to check the functionality of the software for the test cases which have failed earlier. 

4. The test cases which are used in regression testing are usually derived from the user manuals, defect reports, user tutorials, and functional specification in relation to the problem which is corrected. while in case of retesting, we cannot prepare the test cases for retesting before the start of the testing. In retesting the test cases which are failed earlier in previous execution are re-executed. 

5. In retesting, automation of test cases cannot be done while in regression testing automation is the key for effective regression testing. This is because in regression testing when manual testing is performed a lot of efforts and resources are required and with each new update and release the cost and efforts involved in manual testing will keep on increasing. 

6. The verification of defects doesn't come under the category of regression testing. While in the case of retesting, verification of defects falls under the category of retesting. 

7. Regression testing and retesting can be carried out side by side at the same time depending on the availability of resources. But in most cases the retesting is given more priority than regression testing, therefore, it is carried out before doing regression testing. 

In conclusion, the retesting process is performed to check whether the same bug is fixed or not using several steps which are different based on the type of bug or defect. In regression testing, we check whether the modifications like fixing of a bug doesn’t affect the unmodified part of the software. 

The Future of Regression Testing

With the fast pace advancement in technology the tools for testing the tools holds a very bright future. With the advancement in technology, the need for regression testing will increase and the technique for performing regression testing will evolve as well. There is some factor which will greatly impact the future of regression testing and the future of software testing as well. 

Artificial Intelligence

This is a very fascinating topic and everybody is aware of artificial intelligence. The most amazing things about artificial intelligence are that everyone knows about this topic but at the same time, they don’t know about this topic. This is a rhetorical statement but it’s very true. 

With the advancements of artificial intelligence, the regression testing technique will improve significantly. As many processes that are involved in regression testing can be automated so a lot of resources and efforts can be saved. 

The process of regression testing will be more effective and less time consuming and one of the best things is that the regression testing can be performed after every small modification in software with the help of artificial intelligence hence the software will be completely bug-free. 

Read more => Artificial Intelligence and AI Software Testing Tools

QA As A Service 

You might be aware of software as a service (SaaS) and platform as a service (PaaS). Nowadays Quality Assurance as a Service has become popular and it has a huge impact on the future of not only regression testing but every other software testing as well. 

QAaaS solutions make the procedure of regression testing easier thus reducing the cost and efforts involved in the classic regression testing methodologies. QAaaS provide many features such as test case maintenance and management solutions and tools for test automation which requires less coding. 

It also offers easy integration with other platforms as well. It also provides the feature of good test reporting. 

Read more => QA Testing Service Companies: How They Work


Regression testing is very beneficial in software development as frequent changes are made in the software and with regression testing, the bug arising due to these modifications can be identified and fixed. Regression testing allows the organization to make sudden changes in the software and no harm will be caused due to those changes. 

Regression testing should be performed whenever any new change is introduced in the software but with increasing updates the cost and effort involved in manual testing increases rapidly, therefore, automation tools for regression testing are employed to keep things going and ensuring that no extra resources are wasted. 

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Grzegorz Kłos
Grzegorz Kłos - Apphawks Co-founder
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