7 Types of Regression Testing in Software Engineering

Malfunctions or flaws often lead to a sequence of chain reactions that can affect the software altogether as the program runs, impairing the overall user experience. Usually, the software undergoes many tests before Dev teams introduce modifications introduced in the main code. Regression testing is the final step of this process, which is an assurance of achieving a fully functional application or software. In this post, let’s explore seven different types of regression testing.

What is Regression Testing?

Regression testing is a software testing process in which testers verify that the updates performed in the codebase do not adversely affect other software functionalities. In a nutshell, regression testing is the process of checking earlier-passed test cases against a new software version to make sure that it still functions as intended.

Common examples of code changes include the addition of new functionalities, bug fixing, or version updates. When making changes to code, the implications can quickly snowball and have an effect on other software components or cause more profound dependencies. Therefore, it is important to be aware of the potential outcomes of these modifications.

Generally, regression testing refers to a set of tests carried out when new code additions are implemented rather than just a single test.

When Should You Perform Regression Testing?

Various types of regression testing should be executed in the case of modifications or alterations to the codebase. The more often the regression testing is performed, the better: partial regression testing executed at regular intervals will help the Dev team fix the reported defects within the deadlines and avoid any prolonged issues caused by inefficient code quality.

However, even though frequent regression testing from time to time might enable verification of the codebase at regular intervals, developing and sustaining such a variety of regression tests at scale may not be possible. Therefore, it is essential to understand when to start regression testing.

When there is an addition of a new feature

The most common scenario in which testers perform regression tests is when new functionality is introduced. It is difficult for the Dev team to go through every thread in the code during update, and there’s always a hazard of compatibility issues with the current code. Regression testing saves a lot of time for the Dev team with the timely detection of errors that would otherwise cause the software much damage if detected at later stages.

When there is an update in current strategy

Sometimes, sudden updates in the existing business strategy and requirements can lead to an entire modification of the current functionality, requiring developers to revise, reshape, or even toss some attributes. Significant interference with the source code may lead to a lot of impairment to other functionalities, making regression testing an absolute necessity in such cases.

When the bugs are rectified

Attempts at correcting one error sometimes lead to even more errors occurring in the codebase where developers might expect the least. Debugging recommends creating effective and nominal changes to the source code, reviewing bug updates, and frequently going through identical steps. This proves the significance of performing debugging with regression testing to ensure it didn’t yield more bugs than fixed and everything works as planned post-debugging.

When there is a performance-based fix

Let’s say a website took 6 seconds to load, and developers successfully reduced the loading time to 1 second. Post the performance fix, it becomes quite a task for the Dev team to go through each line of code and ensure nothing else was broken in the process. In such instances, Regression testing again saves developers a lot of effort by ensuring none of the other features was hampered when the Dev team handled the performance issues.

Regression Testing Process

Regression testing is done after unit and integration tests and before user acceptance tests. This ensures that all modifications and updates have been properly tested before being released into production. The following are the key processes involved in regression testing.

Regression testing across the builds

Regression testing at the build level resembles testing during the second build of the forthcoming release.

• It occurs when there are code changes or bug fixes across the builds.


• QA retests the bug fixes first, followed by testing the impact area.


• This build cycle persists until a steady build is accomplished.


• QA is usually acquainted with the software version and uses its product knowledge to determine the impact areas.

Regression testing across the release

Regression testing at the release level resembles testing during the second release of an application.

• It always begins from the second software release.


• In most cases, when organizations seek to add or improve existing functionality, a new release is scheduled, for which regression testing across the release is done.


• Release-level regression testing refers to testing on the affected area and involves running regression test cases accordingly.

Advantages of Regression Testing

There is no denying the fact that regression testing is one of the preferred software and application testing techniques. This testing is significant when making changes to complex systems as it allows developers to verify that the new code works correctly with existing code and does not introduce any new bugs.

Regression testing also ensures the quality of applications, as it can help identify issues that may arise due to changes made during development. It helps ensure that the system behaves as expected after making any changes or upgrades. Additionally, regression testing can help improve the overall performance of a system by identifying areas where improvements are needed.

The testing team can relish its advantages across development cycles if implemented correctly. Below are some of the critical advantages of regression testing:

• Determines bugs produced by new code modifications or additions. This motivates teams to work on enhancing the overall application quality.


• Facilitates the scope of automation, as many regression testing types are ideal candidates for automation, which improves the testing process with significant accuracy and detects bugs in less time.


• Complements well with integration testing when new divisions of software features are added.


• Confirms that bugs and defects that are previously patched do not repeat.


• Ensures that any modification in the application’s code has not impacted the already verified code.

With regression testing, the users acquire the software with the lowest possible bugs.

Disadvantages of Regression Testing

Although regression testing delivers many benefits, there are challenges in executing practical regression tests at various levels:

• If the software has recurring updates, regression testing must be repeated and may add up to the testing cost.


• Most of the test cases are redundant, so automation is preferred to save time and effort. Executing automated regression tests comes with an initial cost.

Types of Regression Testing

Here are the seven types of regression testing:

Corrective Regression Testing

This form of regression testing is utilized when no modifications are made to the product’s specification. Moreover, the current test cases can be readily reused to perform the expected test.

Retest-all Regression Testing

Retest-all regression testing is a complicated form of testing. It demands all the system’s specifications should be verified from the origin. It reviews every minor change the software has experienced since its development. The most typical retest scenario occurs after other regression tests have failed to identify the source of the concern, as development teams reckon the issue happened far before the recent code modifications.

Selective Regression Testing

It is performed to identify how the code behaves when new code is added to the existing code. When this form of regression testing is performed, a subset from the current test cases is utilized to lower the effort and cost needed for retesting. For example, a test unit is re-run when an update is incorporated into the program, like functions and variables.

Progressive Regression Testing

This type of regression testing yields more significant outputs when specific modifications are made in the program and new test cases are developed. Performing this testing helps ensure that there are no elements in the prior version that may be compromised in the latest and revised version.

Complete Regression Testing

This process of regression testing is ideally used in case numerous updates are performed on the existing code. Additionally, complete regression testing is used when the new updates to the source code have a distinct impact on the overall software. Conducting this type of testing is favorable in identifying bugs that often go unforeseen. Once complete regression testing is concluded, the final software version can be made available to the user.

Partial Regression Testing

This form of software regression testing is conducted to validate the issues when new code is pushed to an already existing code. Partial regression testing ensures that a system functions as expected after adding the new code.

Unit Regression Testing

It is a crucial regression testing type that is primarily conducted in isolation and mainly focused on code units. All the dependencies and interactions are barred during unit regression testing.

How to Improve the Effectiveness of Regression Testing

Focus on fundamentals

Regression tests are often straightforward and affirmative. In most cases, the tests are so uncomplicated they seem insignificant. However, such functions may be necessary to make the overall software perform as desired.

Create a restorable source

The ability to execute periodic regression tests is based on the availability of test data that may be repeated. Regression test data creation and management should be a part of the automation solution.

Govern the scope of testing

Initially, handling the scope of regression testing can be challenging. This is primarily because testers have to create, execute, and evaluate the regression tests in a limited time. A recommended way to go with regression testing is to identify the easy targets for regression testing as soon as possible.

Design efficient regression tests

Testers need to execute adequate test design strategies to achieve test case efficiency, which is purposed to achieve the most test scope from the minimum number of tests. These may be in the form of decision tables, pairwise test designs, and so on.

Aim for a repeatable strategy

Regression testing immensely relies on exact repeatability. This level of repeatability is achievable with a more comprehensive and highly repeatable testing procedure. When executing and resembling two regression tests of the same operation, the tests must be launched as similarly as possible. There may be deviations due to differences in a recent version, but the concept is to remain as constant as possible.

Use Automation Tools

Executing regression tests frequently at any substantial scale requires accuracy and precision. Manual regression testing is prone to errors. It’s easy to accidentally lose sight when managing redundant test cases. This is why automation is the advised method to accomplish effective regression testing.

Another key reason for choosing automated regression testing is its diverse scope of testing. In the absence of test automation, there is a risk of missing out on the quality goals of the software, leading to contrasts between test versions. Clearly, advanced automated tools, such as Testsigma, are the only way to sustain this effort.

Testsigma delivers a cloud-based test automation platform that holds all the necessary elements for effective automated regression testing. One of the critical features is that the tool suggests the relevant test cases after enhancements or bug fixes are performed on the software.

Testsigma lets testers perform regression tests automatically and enhances the overall capabilities of regression tests with the following features:

• Automates the regression tests using plain English.


• AI generates regression test plans having all the simulated test cases.


• The intelligent interface automatically defends or heals the regression tests in case of UI element changes.


• Reduces the overall feedback time by conducting multiple tests simultaneously.


• Provides steady integration to execute test cases after each new software build.


• Generates test reports to ensure the release readiness of the software.

Critical benefits of Testsigma’s Automated Regression Testing

• Identification of the concerned test cases: The addition of new elements to the code may unintentionally impact parts of the code in other modules. This is primarily due to reliance among modules. Such regressions must be fixed within the sprint to ensure the bug does not move to the production-level code. Testsigma provides AI-driven attributes that automatically identify test cases that may be affected due to such modifications.


• Test case prioritization for faster testing: Testsigma prioritizes and segregates the test cases based on crucial modules, test case classifications, customer-reported bugs, and multiple other custom filters. This facilitates the creation of an optimized regression test plan.


• Reduced feedback time with parallel regression tests: It may need significant time and resources to execute regression tests, including multiple test cases. Testsigma’s parallel execution feature reduces the execution time extensively by trimming the feedback loop and allowing testers to find the bugs more quickly.


• Automated Test Scheduling: Testsigma makes it possible to schedule test executions. This automates the regression testing process, making detecting regressions in the code more straightforward.


• Comprehensive feedback reports: Testsigma tool delivers detailed feedback reports that help stakeholders identify failures and take action on the bugs. It offers exhaustive test reports that enable test results analysis in less time, more efficiently, and effectively. The tool delivers a pictorial representation of the passed and failed test cases, along with screenshots, videos, and detailed descriptions of each test step.

Regression Testing Best Practices

• Develop a policy for various types of regression testing
• Perform the preferred action and match the expected response for the correctness
• Regression tests should be accurate and up-to-date
• Measure the defect escaping capacity during the process
• Create batches of test cases rather than having a single extensive regression test
• Perform regression testing after compilation of every smaller project
• Create regression tests according to the risk factors associated with the business
• Recognize application areas with an increased risk of failure
• Associate regression testing with functional testing
• Re-run successful functional test cases
• Make regression testing an integral part of SDLC

Conclusion

In dynamic software development and agile ecosystems, the product must be constantly upgraded to fulfill the latest expectations of the users. To ensure that these modifications do not impact the current working of the software, regression testing is essential. Regression testing is recommended to confirm that the software stays defect-free even after recurring transformations.

Frequently Asked Questions

What are the techniques of regression testing?

• Regression testing for specific test cases: This form of regression testing approach involves performing specific conditions and prioritizing them for software testing. In this case, testers determine a set of test cases that run in the chain. Based on the use case, the benchmarks to assess these test cases involve estimating the failure rate, overall consequence on the business, or the magnitude of use of the appropriate software feature or functionality. Other high-priority test cases can have recently added software features or essential aspects of the software.


• Segmented regression testing: For this approach, testers choose the appropriate sections of the software in advance – the introduction of new features probably impacts these sections. Then, regression testing is executed only on the selected code. This can be further implemented into corresponding code areas for more reasonable testing coverage. However, by choosing the right test cases, testers can significantly bring down the time, cost, and effort needed to conclude the testing process. Compared with regression testing for specific test cases, as mentioned above, testers prioritize specific software segments in this case.


• Complete regression testing: This is a comprehensive form of regression testing. While this method needs the most time and effort, it also ensures that all potential bugs get identified and resolved. Despite its heavy necessity, this approach might be the best option for some projects. For example, complete regression testing can be a wise decision when there is a notable platform update or upgrade or when the software is being revamped for a unique platform.

What is an example of a regression test?

Let’s say an application has a programmed feature to launch a series of events, such as verification, confirmation, and sharing emails when the assigned CTAs are tapped.

Let’s assume a minor issue is noticed in the triggered email function. For the Dev team to deal with the bug, some subtle changes need to be made in the code. When a developer is addressing the issue, they will only validate the automated email triggers.

However, regression testing post-bug fixing will involve validating the email triggers and associated features of the application. The validation and approval processes will be cross-checked to confirm their functions are still unharmed and that the code modification didn’t cause additional problems, no matter how small.

Which type of regression is best?

Corrective regression testing is one of the highly recommended types of testing. Corrective regression testing is also executed on current test cases because it takes less time to find bugs. The process is suitable and readily used repeatedly to perform the necessary test from time to time.