What is Regression Testing? Regression Testing Tutorial Guide for Beginners

We live in an era of technology where software programs and applications have become an important part of our lives. When a software program is created, it is not simply released, but it has to go through different types of software testing before the final deployment. The software testing process validates or verifies a software product from technical and functional prospects.

The software testing ensures the product is working the same way for which purpose it was designed. Additionally, software testing helps to identify errors, gaps in opposing to the actual requirements. There are different types of software testing that are either performed individually or they can be used in combinations based on requirements.

• Unit Testing
• Integration Testing
• Functional Testing
• System Testing
• Stress Testing
• Performance Testing
• Usability Testing
• Acceptance Testing
• Regression Testing
• Beta Testing

In this blog, our main focus of discussion is Regression Testing. If you are planning to learn regression testing fundamentals at the beginner level or want to appear for an interview, then this blog is written for you. Other than this, you would also check regression testing interview questions answers to increase your chances of getting selected by top MNCs.

The major topics covered in the blog include:

• What is Regression Testing?
  • Regression Testing Highlights
  • When to perform regression testing
  • Can regression testing be done manually?
  • Challenges in Regression Testing
  • Best Practices in Regression Testing
• Regression Testing Tools
  • Selenium
  • QTP (Quick Test Professional)
  • RFT (Rational Functional Tester)
• Retest Vs Regression Testing
  • What are the similarities?
  • What are the differences?
• Automated Regression Testing in Agile
  • Sprint Level Regression
  • End to End Regression
• Why the Regression Test?
• Types of Regression Testing
  • Unit Testing
  • Partial Regression
  • Complete Regression
• How Much Regression Testing is Required?
• Regression Testing Techniques
  • Retest all
  • Regression Test Selection
  • Test case Prioritization
  • Hybrid
• How to Select the Regression Test Suite?
• How to Perform Regression Testing?

Let us discuss each of regression testing fundamentals in detail below.

What is Regression Testing?

Regression testing is performed to check that a code change does not impact the existing functionality of the product. In simple words, Regression testing means retesting the unchanged part of an application. Also, the test cases are executed again to verify that the product is behaving like previous and new bugs are not introduced in the product.

Regression Testing Highlights:

• It is a verification method that is usually automated because test cases are executed again and again. The manual execution of test cases is time-consuming and tedious here. To check the comparison between manual and automation testing, click here.
• It is generally performed on the new build and fixes bugs too if anything is detected.
• It is not dependent on any programming language but a testing method that verifies that bugs are fixed well and new changes have not introduced any defect in the functionality of a product.
• It is a part of the release cycle and must be considered mandatory in the test estimation.

When to perform Regression Testing?

This is a logical question because a product takes several weeks or months sometimes for the next release cycle. So, it would be great incorporating regression testing in your daily release cycles. It can be performed weekly when functional testing for the product is over.

Most of the times, a product is retested because application code is changed occasionally not daily. The major objective of the regression testing is to make the new build or new version more functional without any bugs.

Can Regression testing be performed manually?

Software testing is all about the execution of test cases, and the test execution is so simple that we don’t need any special tools to perform it.  So, it is just a misconception that regression testing should always be performed via automation.

Read: Unit Testing Interview Questions and Answers

It can be done manually when your test cases change frequently. For the build, if test cases are fixed, then automation testing can be a good choice here.

Challenges in Regression Testing

Regression Testing is a vital process in software engineering, but it comes with some challenges as given below.

• Complex: When your product is frequently updated then regression test cases become quite complex, and list of tests to the regression pack grows to a huge amount.
• Time-Consuming: Regression testing generally takes more time to complete especially when it is done manually. When the same test cases are executed, again and again, testers are not so enthusiastic about performing regression tests in that case.
• Weak communication: Regression testing is not able to communicate the business value to non-technical leaders as expected. It takes considerable time investment in regression testing to ensure that the product is behaving the same way as per the requirement.

Best Practices for Regression Testing

Here are some best practices to keep in mind when you perform regression testing on a software build.

• You should update the regression pack A regression pack is the set of test cases that are performed when updates to a software build are complete.
• You should focus more on highly trafficked paths that are used most often for your software build.
• You should re-run successful test cases that can identify and fix bugs quickly.
• You should automate regression test cases that are used over again and again. It keeps the testers motivated and saves the overall testing time too.

Regression Testing Tools

If your software build requires frequent changes, then costs for regression tests will increase significantly. In such cases, the manual execution of test cases increases and cost investment too. For the test cases that remain the same for some builds, automation testing is a smart choice.

Following are the QA tools that are suitable for both regression testing and functional testing. However, when you add automation tools for regression tests, make sure that tool allows you to add or update test cases frequently. Three popular regression testing tools in 2019 are given as:

• Selenium: This is an open source tool to automate web apps. It is highly suitable for browser-based regression testing. To know about Selenium tool in detail, Click here.
• Rational Functional Tester (RTF): This is a Java-based tool given by IBM to automate the test cases for a software application. It can be integrated with other testing tools or test managers if required.
• Quick Test Professional (QTP): It is an automated software designed to automate the functional and regression test cases. It is a data-driven, keyword-based tool uses VBScript programming language to automate the test cases.

Retest vs. Regression Testing

What are the similarities?

• They both are repetition based testing techniques.
• They both are validation and black box techniques.
• They both allow regression and retesting of manual or automated test cases.
• They allow to verify or expel doubts and convert them to a certainty of Yes or No.

What are the differences?

• Retesting targets current and previous functionality. However, regression testing targets previous functionality only.
• Regression testing is change-oriented while retesting is not based on changes.

So, it is clear from the discussion neither one nor another but the combination of both testing techniques makes a dynamic duo.

Read: Software Testing Engineer Career Path: Role & Job Responsibilities

Automated Regression Testing in Agile

The Agile approach is common is software testing based on iterative and incremental methodologies. The product is developed in short iterations that last for 2-4 weeks (Sprint). Testers should design test suite at the initial phase that is updated with each Sprint. The automated regression testing in agile is divided into two categories as given below.

Sprint Level Regression

This regression is performed on new features or enhancement made in the latest Sprint. Testers should select test cases from the test suite based on new added functionalities or enhancements.

End-to-End Regression

This regression includes all test cases that need to be executed for testing the whole product and covers all core functionalities of a product.

Agile methodology has short sprints, and it goes on, it is highly required automating the test suite executed over again and again within a short period. Automating the execution of test cases reduces the overall testing time and defect slippage.

Why the Regression Test?

Regression testing is done when developers add new code or new features to the system. There are plenty of dependencies in newly added and existing functionalities. And it is true that when one bug is fixed several new bugs are introduced without your knowledge.

It is necessary to check either new code complies the older ones so that the unmodified code is not affected. Mostly, the testing team has the task to check last-minute changes in the system. Here, it is necessary to complete the testing process on time by covering all major system aspects.

Regression testing is considered more important for continuous changes in the system that should not negatively affect the existing code. Regression testing is done to find bugs due to the newly added code. If testing is not done, the product may get critical issues that eventually lead the customer into trouble.

Example: Take the example of a website where the cost of the product is not displayed correctly if it is not fixed soon then the customer has to bear the loss. So, Regression Testing plays an important role here and much required for any software product or web application.

Type of Regression Testing

There are three types of Regression Testing, these are Unit Regression, partial regression, and the complete regression.

Read: ETL Testing Tutorial Guide for Beginners

• Unit testing is done during the unit testing phase in isolation. Any dependencies on the unit are blocked so that each of the units can be tested individually.
• Partial Regression testing is done to verify the code when tested units are integrated with the existing code.
• Complete Regression Testing is done when changes to modules are uncertain. Here, the product is tested as the whole instead of individual units.

How much Regression Testing is Required?

It depends on the scope of newly added features. If the scope is large, then the application area getting affected is also very large. Here, testing should be performed thoroughly including all application test cases. For this purpose, testers need input from developers about the scope and nature of the product.

Be careful while selecting regression test cases to cover maximum functionality in a limited number of test cases. These test cases need continuous improvements based on newly added functionalities. It is difficult performing regression testing when the scope of application is huge. So, selective test cases should be tested to save time and reduce costs.

Regression Testing Techniques

• Retest All: As the name suggests, all test cases should be executed again to make sure that there are no bugs because of changes in the code. It is usually expensive and needs more resources and time when compared to other regression testing techniques.
• Regression test selection: It is difficult performing regression testing when the scope of application is huge. So, selective test cases should be tested to save time and reduce costs. Be careful while selecting regression test cases to cover maximum functionality in a limited number of test cases. These test cases need continuous improvements based on newly added functionalities.
• Test case Prioritization: Once you have selected regression test cases, they should be arranged based on priority from medium to high. The high priority test cases should be executed first. The priority for the test cases is usually decided based on their impact on the functionality of the product.
• Hybrid: it is a combination of test case selection and test case prioritization. Instead of working on the product as a whole, it is always good to make a selective decision and perform the testing accordingly.

How to select the Regression Test Suite?

Most of the bugs in a software build occur due to changes in the code. It is necessary to fix those bugs to maintain the functionality of a product. This is the reason why regression testing is considered so important for any software product. Here are important facts to keep in mind while selecting the regression test suite:

• Focus on functionalities that are changed quickly.
• Focus on test cases that cover modules where changes are made.
• Focus on complex test cases.
• Focus on test case integration that includes the major components.
• Focus on test cases that cover the core functionalities of a product.
• Focus on test case priorities before the final execution.
• Focus on test cases that fail frequently or more suspected of defects.

How to perform the Regression Testing?

Now, when you know almost everything about Regression testing, it is the right time to discuss how to perform the Regression Testing. Regression testing can be done manually, but it usually takes time. To save your time and associated costs, the regression testing is often automated. Here are some important steps involved in performing the regression testing successfully:

• First, prepare a test suite when you already know how to select the regression test suite.
• Now automate the test cases in the test suite.
• You should update the regression suite frequently. A regression suite is the set of test cases that are performed when updates to a software build are complete.
• Execute the regression test cases whenever there are changes in the code or new features or enhancements are added to the product.
• At the final step, create the test execution report that shows the pass/fails status of the executed test cases.

Every time a software product undergoes a change or a new version is released, the following steps you should carry out to perform the Regression testing.

• At the first stage, understand the type of changes in depth that are recently made to the software.
• At the second step, analyze and determine the modules that can be impacted through changes. BA team is more instrumental here in providing this information.
• At the third step, check the test cases thoroughly and decide on the type of regression testing, i.e., Unit Testing, Partial Regression, or Complete Regression.
• In the last step, schedule the time and test right away.

Final Words:

Regression Testing is a crucial step in software testing that makes sure that changes to the code either small or big will not affect the product functionality anyhow. There are a lot of automation tools available to make things easy for you. However, the selection of tool major depends on project requirements and your budget. The tool should have the ability to update the test suite as required.

With this discussion, we hope the topic is clear in depth now. Don’t forget to add comments how did you tackle your regression testing tasks? To know more on different types of testing in Software engineering, join QA certification program at JanBask Training and explore your knowledge base now.

Read: Manual Testing Tutorials For Beginners