What is Regression Testing? [Definition, Types, & Tools]

In software development, ensuring the high quality of software products is of paramount importance, and this is where software testing comes into play. Software testing assures that a software product under development conforms to quality standards as well as customer requirements. End-users will never want a software product that has bugs. Therefore, software testing is very significant.

The quality assurance (QA) team or the team of skilled testers conducts various types of software testing to examine the correctness of the software products under various circumstances. Moreover, they aim to make the software products defect-free before releasing them publicly.

Regression testing is one of the types of software testing that involves re-executing functional and non-functional tests to ensure that the software product works the same even after a small change.

If you want to learn more about regression testing, this article is for you. In this article, we are going to make you familiar with regression testing in detail.

So, let us get things moving!

What is Regression Testing?

Regression testing is a type of software testing that the quality assurance (QA) team conducts to check whether the software product functions correctly after making changes or improvements to its source code.

In simple words, regression testing ensures that any changes in the codebase of the software product do not affect its existing functionality. Here, code changes may be due to fixing bugs, adding new features, or updating any current feature.

Alternatively, we can define regression testing as re-executing existing functional and non-functional tests (executed successfully against the previous software build) against the new version of the software product to validate its functionality. More importantly, this type of testing does not involve executing a single test. Instead, it involves executing a series of tests after modifying the source code.

Why Regression Testing?

Let us consider one simple example to understand this type of software testing. Consider you are a software development firm, and you got a project that requires you to develop a software product for online food ordering. You successfully develop the first build of the software product based on the primary requirements provided by the client.

Later, you create multiple test cases, let us say 500, to test that software product and check whether it meets the clients’ requirements. Once done, you deliver the first build of the software product to the client.

Though the client is happy with the first build, he wants some extra features to incorporate into the software product and conveys the same to you. Therefore, now you started working to add new features to the existing system.

Once done, you perform testing with a few more additional test cases, along with the previous ones. You execute new test cases to check the newly added code. On the other hand, you run existing test cases to ensure that the new code does not affect the old code or the existing functionality of the software product. This type of testing is called regression testing.

Advantages

Here are some remarkable advantages of regression testing:

• This type of testing ensures that any change in the source code does not affect other functionalities of the software product.
• It helps in performance optimization and improves the overall quality of the software product.
• It ensures that the defects, once fixed, do not recur.
• This type of testing acts as a risk mitigation strategy during testing.
• It is easy to learn and understand.

Disadvantages

The following are the major disadvantages of regression testing:

• If you conduct this type of testing manually, it consumes a lot of time and becomes a tedious process.
• You need to perform this testing for every small change you make in the source code.
• It becomes pretty difficult to achieve the maximum test coverage with fewer test cases.
• You need to create complex test cases, which is again a time-consuming process.

When to Perform Regression Check?

The QA team conducts the regression check on the software product in the following circumstances:

• The system undergoes the regression check when new functionality is incorporated into the software product. For example, consider that you have a login page where users can log in using their mobile numbers. But you add new functionality that allows users to log in through their Facebook account. Thus, you need to do a regression check on the system to test the new functionality.
• As we know, customers’ requirements can change anytime. They may come up with new requirements at any time during the development. As a result, the QA team performs the regression check on the system whenever there is a change in requirements.
• When the development team fixes a bug and sends the modified code to the QA team, they perform the regression check to ensure that the modified code does not affect the existing functionality of the software product.
• The regression check takes place after the performance issue fix.

Regression Testing Types and Techniques

Types

There are five types of regression testing that are as follows:

• Corrective: In this type of testing, the QA team checks the software system to check whether it is working correctly or not. They run only the existing test cases and do not create new ones.
• Progressive: This type of testing is ideal when a new component is added to the software. It helps to verify that the introduction of a new component does not affect the existing functionality of the software product.
• Selective: In selective testing, the QA team tests only the selected component of the software product.
• Partial: Partial testing helps the QA team to determine the effect of each new line of code added to the existing source code. Unlike selective testing, both new and old functionalities undergo the regression check.
• Complete: The QA team performs the complete testing on the entire software product before making it live to end-users.

Techniques

The following are the different types of regression testing techniques:

1. Retest All

Retest All is one of the most common methods to perform regression testing. It involves retesting all the previous test cases to ensure that the software system works well and there are no bugs in it even if you introduce the changes in its codebase. However, this technique requires a lot of time, effort, and resources. Hence, it is expensive.

2. Regression Test Selection

Unlike the retest all technique, the quality assurance team does not run all the test cases in the Regression Test Selection. Instead, they select certain test cases based on the code changes.

Furthermore, the selected test cases are categorized into two types, reusable and obsolete. The QA team can use the reusable test case cases in the succeeding regression cycle, while they cannot use obsolete test cases in succeeding cycles.

3. Prioritization of Test Cases

As its name suggests, this method involves executing test cases with high priority. The QA team first executes the high priority test cases and later the medium and low priority test cases. Moreover, the priority of the test cases depends on their effect on the software product.

4. Hybrid

This type of technique is the amalgamation of regression test selection and prioritization of test cases. In this technique, the QA team first selects the test cases and then executes the ones with high priority.

Regression Testing Tools

There are two ways to perform regression testing, namely manual and automated. However, manual testing takes a lot of time and is quite tedious. Therefore, most organizations adopt automated testing. They leverage different tools to carry out automated testing. Here are some of the most popular regression testing tools :

1. Selenium

Selenium is an open-source suite of tools and libraries for automated browser testing. This suite consists of three components, namely Selenium WebDriver, Selenium Grid, and Selenium IDE.

In Selenium IDE, you can write functional test scripts without having the knowledge of any programming language because it uses a domain-specific language called Selenese. This language allows you to write test scripts in various programming languages, such as Java, C#, JavaScript, Perl, etc.

Selenium WebDriver uses Selenium Server that drives your browser natively either locally or on a remote machine. Finally, Selenium Grid lets you run the test scripts on multiple remote machines.

2. Katalon Studio

Katalon Studio is an all-in-one test automation platform. It is built on top of the open-source automation frameworks, such as Selenium and Appium.

In addition, this tool comes with a fully-featured IDE for web, mobile, API, and desktop application testing. Any beginner with limited programming experience can write tests using this IDE. Moreover, it provides the feature of recording the GUI elements on the web, mobile, and desktop applications and storing them in the Object Repository for maximum reusability.

3. Watir

Watir is an open-source Ruby library for automation testing. It primarily consists of three components, namely Watir-classic, Watir-webdriver, and Watirspec. It is available as a RubyGems gem.

Watir-classic leverages the Object Linking and Embedding (OLE) capabilities and directly drives a browser rather than simulating the browser. Next, Watir-webdriver is an advanced version of Watir API and is based on Selenium. Also, Watirspec is an executable specification of Watir API.

4. TestSigma

TestSigma is an open-source cloud-based automation testing framework. You can install the instance of TestSigma either on your local desktop or directly sign-up on the cloud-hosted platform.

Moreover, you can create test scripts in simple English language or record user actions to create test scripts within minutes. It lets you execute your test scripts across 800+ browsers and 2000+ devices on the cloud-hosted test lab.

5. IBM Rational Functional Tester

IBM Rational Functional Tester enables you to carry out automated GUI, regression, functional, and data-driven testing. It provides support for a variety of applications, such as Java, .Net, web-based, SAP, and terminal emulator-based applications.

This tool leverages the ScriptAssure technology, which helps you to carry out automated testing on frequently changing GUIs. Since it supports data-driven testing, it allows you to conduct tests with a varying test data set. Moreover, it comes with a recorder that records user actions.

Challenges and Best Practices of Regression Testing

Challenges

While performing regression testing, organizations may face many challenges, including the most popular ones listed below:

• High Upfront Cost: As mentioned earlier, performing regression testing manually is tedious and time-consuming. On the other hand, automated testing requires high-end infrastructure and tools, which are pretty expensive.
• Testing Approach: To ensure successful testing, it is important to choose the right approach. This simply means that it is significant to have a proper test plan to carry out successful testing. So, if the QA team does not have a clear test plan, they may face difficulties while conducting testing.
• Skilled Resources: To perform this type of testing, it is necessary to have skilled resources, which are very difficult to find.
• Test Coverage: The QA team often minimizes test suites due to time and budget constraints. However, it becomes challenging to ensure the maximum test coverage with minimum test suites.
• Complexity: As the QA team develops various software builds, the number of test cases increases. Therefore, regression testing becomes complex.

Best Practices

Here are some best practices that you should follow while performing regression testing to make it successful:

• Choose the test cases that result in frequent defects.
• Maintain the regression test suite by including high-priority and high-value test cases regularly.
• Execute regression tests after functional testing.
• Make sure to have a clear regression test plan.
• Run regression test cases regularly.
• Pick the right test tool to facilitate the testing process.

Conclusion

Regression testing plays a vital role in the software testing life cycle (STLC) to ensure that any changes in the codebase do not affect the system’s existing functionality. It helps organizations ensure that the software products about to go live are high-quality and robust. In addition, it helps the QA team to identify new bugs and defects even when there is a small change in the software product's source code.

Hopefully, this article has provided you with in-depth insights into regression testing, along with its types, techniques, challenges, best practices, and popular testing tools.

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