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Regression Test Overview
The goal of software testing is to find and fix bugs. However, after a bug gets fixed, other bugs often ensue. This is when Regression testing comes into play. It ensures that additional problems do not arise after a bug fix or a code change. Hence, every software product company performs Regression tests.
Regression testing is executed after making changes to a software product and retests the product areas that may have been impacted by the fix. This can be automated or performed manually by executing a particular set of test cases (test scripts in case of Automation). No matter how the regression test is executed, this type of testing is critical for delivering a high-quality software product.
Regression Testing is defined as a type of software testing to confirm that a recent program or code change has not adversely affected existing features. Regression Testing is nothing but a full or partial selection of already executed test cases that are re-executed to ensure existing functionalities work fine.
This testing is done to ensure that new code changes do not have side effects on the existing functionalities. It ensures that the old code still works once the latest code changes are done.
For Example, Consider a product X, in which one of the functionality is to trigger confirmation, acceptance, and dispatched emails when the Confirm, Accept and Dispatch buttons are clicked.
Some issues occur in the confirmation email and in order to fix the same, some code changes are made. In this case, not only the Confirmation emails need to be tested, but Acceptance and Dispatched emails also need to be tested to ensure that the change in the code has not affected them.
When to Perform This Test?
When new features or enhancements are deployed to an existing codebase or application, Regression testing is required. It ensures that any new functionality or update to an existing application works properly without any bugs or defects. Developers and testers often struggle to trace every code thread, with significant chances of code incompatibility issues. As a result, executing Regression tests of their codebase (or application) allows them to detect defects earlier and ship applications with fewer risks.
Regression Testing is usually performed after verification of changes or new functionality. But this is not always the case. For the release that is taking months to complete, regression tests must be incorporated in the daily test cycle. For weekly releases, regression tests can be performed when Functional Testing is over for the changes.
Regression checking is a variation of retest (which is simply to repeat a test). When Retesting, the reason can be anything. Say, you were testing a particular feature and it was the end of the day- you could not finish testing and had to stop the process without deciding if the test passed/failed.
The next day when you come back, you perform the test once more – that means you are repeating a test you performed before. The simple act of repeating a test is a Retest.
A regression test at its core is a retest of sorts. It is only for the special occasion that something in the application/code has changed. It might be code, design or anything at all that dictates the overall framework of the system.
Types of Regression Testing
Depending on your Software Development Life Cycle (SDLC) and the new feature or update you aim to deploy, you can implement various types of regression tests. However, it is essential to understand the several regression tests types to choose the right one.
Below are the different types of regression testing –
Corrective Regression Testing
Corrective Regression testing is one of the simpler forms of Regression tests requiring minimal effort. Corrective Regression testing involves no changes to the existing codebase and adding new functionality to the application. You simply need to test the existing functionality and the test cases that go with it rather than creating new ones.
Unit Regression Testing
Unit Regression testing is an integral part of Regression tests in which the code is tested in isolation. All other interactions, integration, and dependencies are disabled while performing unit Regression testing, and the emphasis is on single unit code. Typically, this testing is done during low traffic and off-peak hours.
Selective Regression Testing
Selective Regression testing analyzes the impact of existing code and the effect of both new and existing code. Common elements like variables and functions are incorporated into the application to identify quick results without affecting the process.
Progressive Regression Testing
Test cases are created based on the requirements of a progressive regression test. When there are only minor product improvements, the new test cases are designed without affecting the existing code of a product.
Complete Regression Testing
Some minor or significant changes might have a massive impact on the product. Complete Regression testing is used in this instance when there are significant modifications to the current code. It aids in the repair of any modifications made during the testing process.
Partial Regression Testing
When new code is added to an existing codebase, partial Regression testing is conducted. This aids in the discovery of critical bugs in existing code and allows them to be tested without affecting the system.
Retest-all Regression Testing
Re-test all Regression testing is the process of re-executing all the test cases to ensure that there are no bugs due to code changes in an application. This type of testing needs immense effort from the QA front.
Advantages of Regression Testing
The software market growth relies heavily on the success of Regression tests. Besides functional tests, Regression tests must be performed at each stage to ensure application stability. DevOps teams can utilize Regression tests in their software development lifecycle and ensure their existing code isn’t affected by the newly added updates and features.
Below are a few advantages of Regression testing:
It ensures smooth business operations by ensuring the new features are not affecting the existing codebase, dramatically improving the overall product quality.
Regression tests may be used during the integration testing phase also. In this case, they will help detect bugs across different systems when putting two systems together.
Manual test cases can be automated, and this automation principle can be applied to Regression checks. Automated Regression testing can help you cut down test execution time by multiple folds.
A successfully executed Regression test suite ensures that the bugs are detected and fixed early and eventually helps achieve a high Customer Satisfaction Index (CSI).
It thoroughly validates that the code modifications do not impact the correct functionality of already tested code – detect every side effect of any code change.
Selecting test cases for regression testing
It was found from industry data that a good number of the defects reported by customers were due to last minute bug fixes creating side effects and hence selecting the Test Case for regression testing is an art and not that easy. Effective Regression Tests can be done by selecting the following test cases –
Test cases that have frequent defects
Functionalities that are more visible to last-minutethe users
Test cases that verify core features of the product
Test cases of Functionalities which has undergone more recent changes
All Integration Test Cases
All Complex Test Cases
Boundary value test cases
A sample of Successful test cases
A sample of Failure test cases
Regression Testing Tools
usableIf your software undergoes frequent changes, regression testing costs will escalate. In such cases, Manual execution of test cases increases test execution time as well as costs. Automation of regression test cases is the smart choice in such cases. The extent of automation depends on the number of test cases that remain e for successive regression cycles.
Following are the most important tools used for both functional and regression testing in software engineering:
1) testRigor
testRigor helps you to directly express tests as executable specifications in plain English. Users of all technical abilities are able to build end-to-end tests of any complexity covering mobile, web, and API steps in one test. Test steps are expressed on the end-user level instead of relying on details of implementation like XPaths or CSS Selectors.
Features:
The free forever public version
Test cases are in English
Unlimited users & Unlimited tests
The easiest way to learn automation
Recorder for web steps
Integrations with CI/CD and Test case management
Email & SMS testing
Web + Mobile + API steps in one test
2) Avo Assure
Avo Assure is a technology-agnostic, no-code test automation solution that helps you test end-to-end business processes with a few clicks of the buttons. This makes regression testing more straightforward and faster.
Features
Autogenerate test cases with a 100% no-code approach
Test across the web, desktop, mobile, ERP applications, Mainframes, associated emulators, and more with a single solution.
Enable accessibility testing
Execute test cases in a single VM independently or in parallel with Smart Scheduling
Integrate with Jira, Jenkins, ALM, QTest, Salesforce, Sauce Labs, TFS, etc.
Define test plans and design test cases through the Mindmaps feature
3) Virtuoso
Virtuoso puts an end to fiddling with flaky tests in your regression pack on every release by delivering tests that heal themselves. Virtuoso launches bots that dive into the application’s DOM and build a comprehensive model of each element based on available selectors, IDs, and attributes. A Machine Learning algorithm is used on every test run to intelligently identify any unexpected changes, meaning testers can concentrate on finding bugs and not fixing tests.
Regression tests are authored in plain English using Natural Language Programming, much the same way you would author a manual test script. This scripted approach retains all the power and flexibility of a coded approach but with the speed and accessibility of a codeless tool.
· Cross-browser and cross-device, write one test for everywhere.
· The fastest authoring experience.
· A next-generation AI-augmented testing tool.
· Guaranteed in-sprint regression testing.
· Out-of-the-box integration with your CI/CD pipeline.
4) Subject7
Subject7 is a cloud-based, “true codeless” test automation solution that unifies all testing in a single platform and empowers anyone to become an automation expert. Our easy-to-use software enables fast, easy, and sophisticated authoring of regression tests without writing a line of code, and high-scale execution that runs thousands of nightly tests.
Features:
Integrates easily with DevOps/Agile tooling using native plugins, in-app integrations, and open APIs.
High-scale parallel execution in the cloud or on-prem with enterprise-grade security.
Flexible reporting of defects, with video capture of results.
Simple, non-metered pricing, delivering financial predictability.
SOC2 Type2 compliant
Selenium: This is an open-source tool used for automating web applications. Selenium can be used for browser-based regression testing.
5) Katalon
Katalon is an all-in-one platform for test automation with a large user community. It offers free and codeless solutions to automate regression testing. Since it’s a ready-made framework, you can use it right away. No complicated setup is needed.
You can:
Quickly create automated test steps using Record and Playback.
Easily capture test objects and maintain them in a built-in repository (page-object model).
Reuse test assets to scale up the number of automated regression tests.
It also provides more advanced features (like built-in keywords, scripting mode, self-healing, cross-browser testing, test reporting, CI/CD integration, and more) to help QA teams meet their extended testing needs when scaling up.
Types of Regression Testing
Given below are the various types of Regression :
Unit Regression
Partial Regression
Complete Regression
#1) Unit Regression
Unit Regression is done during the Unit Testing phase and code is tested in isolation i.e. any dependencies on the unit to be tested are blocked so that the unit can be tested individually without any discrepancy.
#2) Partial Regression
Partial Regression is done to verify that the code works fine even when the changes have been done in the code and that unit is integrated with the unchanged or already existing code.
#3) Complete Regression
Complete Regression is done when a change in the code is done on a number of modules and also if the change impact of a change in any other module is uncertain. The product as a whole is regressed to check for any changes because of the changed code.
How much Regression is required?
In the previous section, we touched upon selecting the regression test cases. Now let’s look at how much regression is required.
The amount of regression required solely depends on the extent of an application’s new features or updates. If the fix or upgrade is major, extensive Regression tests of all application test cases is required. Since the update is significant, the test cases will also be huge; therefore, you can perform automated testing of all repetitive test cases. For the newly added functionality, the test suites require constant upgrades.
The next step is identifying appropriate Regression test cases in order to cover all of an application’s functionality. However, when the app’s changes are substantial, the most effective approach is to find relevant test cases based on the upgrades and the affected sections of the application. It will help you in cutting costs, time, and effort.
What Do We Do In Regression Check?
Re-run the previously conducted tests.
Compare the current results with previously executed test results
This is a continuous process performed at various stages throughout the software testing lifecycle.
A best practice is to conduct a Regression test after Sanity or Smoke Testing and at the end of Functional testing for a short release.
In order to conduct effective testing, a regression Test Plan should be created. This plan should outline the regression testing strategy and the exit criteria. Performance Testing is also a part of this test to make sure that the system performance is not affected due to the changes made in the system components.
Best practices: Run automated test cases every day in the evening so that any regression side effects can be fixed in the next day build. This way it reduces the release risk by covering almost all regression defects at an early stage rather than finding and fixing those at the end of the release cycle.
How to perform Regression Testing?
Regression testing can be executed both manually and in an automated manner. Test Engineers primarily use special techniques and methods to perform Regression tests.
Below are the phases involved in Regression testing –
Test Case Selection: The selection of test cases is determined by the component, one with a massive number of code modifications. Testers can split the tests into two categories: reusable test cases and obsolete test cases. Reusable test cases will be used in future Regression test cycles, but obsolete test cases will not be considered in further Regression test cycles.
Time Estimation: Following the selection of test cases, the next step is to estimate the test execution time. Test case generation, test case evaluation, and other factors impact test execution time.
Automate Test Cases: Testers should select between manual and automated Regression testing based on the number of test cases after time estimation.
Test Case Prioritization: In this step, testers prioritize test cases based on recent code changes, minimizing Regression time and effort. The test cases with high priority are executed first, followed by medium and low priority.
Test Execution: Finally, all test cases are run in the order of priority to find flaws and ensure that the application is functioning correctly. Automated Regression testing tools like Selenium enable you to reduce test execution time and automate your Regression test suites more quickly.
Challenges of Regression Testing
It helps uncover bugs while introducing new features or updates in an existing codebase and facilitates the mitigation of app crashes and performance bottlenecks. However, while running a Regression test, a tester faces different challenges.
Shown below are a few of the challenges faced by testers –
Test suite cost and time: A Regression test suite requires continuous improvement when new features are deployed. As a result, the number of test cases varies, and new tests must be re-run with older tests, which require a lot of time to complete. Incorporating parallel testing can be a viable solution as it allows you to run test cases concurrently across multiple browsers and OS combinations, reducing lead time by multiple folds.
Complex test cases: As the project or application becomes more complex, the number of test cases and their complexity also rise. Thus, consuming a significant amount of time and resources.
Maintenance: As the application grows in size, the complexity of test cases in Regression test suites increases. Therefore, proper maintenance is vital to handle the complexity and execution time.