Why, Where and How – All Your Regression Testing Questions Answered

The problem is not that testing is the bottleneck. The problem is that you don’t know what’s in the bottle. That’s a problem that testing addresses. — Michael Bolton (Software Testing specialist)

Whether it’s software, web apps or mobile apps, development is all the rage now. There are millions of websites on the Internet and channels on YouTube which sell like hot cakes simply because knowing web development has become a trend.

But there is another component other than development which has to be completed before any app or software is deployed- testing.

Though just like development, software testing has its own complexities and stages, a very critical step of the way is software regression testing in software testing.

In this article, we will walk you through the software development life cycle, where regression testing falls in the cycle and why it is absolutely mandatory before any software is deployed.

Software Development Life Cycle

Software Development Life Cycle or SDLC refers to the process of designing, developing and testing software. It has six well-defined steps, which are carried out for every single project.

1. Planning

2. Defining

3. Designing

4. Development

5. Testing

6. Deployment

Regression testing falls in the 5th stage and is an absolutely mandatory component of testing.

What is Software Regression Testing?

Regression testing is a black-box testing technique that ensures code still functions seamlessly even when the changes occur.

Most of the time, when testers raise a bug or a defect, developers change a piece of code to meet the requirements. In such cases, the testers have to run all functional and non-functional tests again to make sure that the new piece of code has not affected the other functionalities for which code was not changed.

In automated regression testing, testers simply rerun a set of tests to make sure existing functionalities are running without a glitch.

Why is Regression Testing so Important in the SDLC?

Changing code and fixing bugs comes with its own share of issues, and that is exactly what regression testing aims to fix.

Regression testing is very important as it validates whether the functionality is working as expected after making some new changes to the software. Regression testing is also an important part of the software development life cycle (SDLC) as it verifies every functionality and feature of the software once the new feature has been added to the stable.

Every time the developer updates the code or the operating environment, it leads to a change in the way some other piece of code behaves. Regression testing meaning is testers use automated and manual regression testing to ensure these changes in code do not affect any functionality, either major or minor of the software or application.

Benefits of Regression Testing:

Benefits of regression testing in software testing are:

• Helps identify bugs which have been caused by code change
• Improves quality of product
• Alerts both developers and testers about possible effects of updating operating environment

When do Testers Apply Regression Testing?

Testers go for regression testing in the following scenarios:

• Changes are made in existing functionality

On the request of the client, developers may make revisions or edits in the existing functionality. Then it is imperative to check if the previous functionalities are working as desired without any issues.

• New functionality has been added

Whenever developers add any new piece of code, the onus falls on the testers to make sure that the new code does not in any way cause the old code to malfunction.

• On integrations with other products

When the software or application is integrated with another product, the quality assurance team must verify if the application functionalities perform flawlessly.

Manual Regression Testing vs Automation Regression Testing

Software testing is always divided into two parts- manual and automation.

In manual testing, QA engineers manually execute all test cases without the help of software or tools.

In automation testing, the testers automate the test cases using test scripts created using different software testing tools like Selenium and Cucumber.

Thus even regression testing has these divisions.

Manual Regression Testing is:

• Time-consuming
• Random and exploratory testing possible
• Tester need not know any programming knowledge

Automation Regression Testing is:

• Fast
• Random testing is not possible. It will only execute the test cases for which the tester has written the test scripts.
• It is mandatory for the tester to know the programming language required for using the automation testing tools.

Functional Regression Testing vs Non-functional Regression Testing

The job of functional regression testing is to check that all functionalities of the application are running as per requirement even after addition or revision of code.

Whereas, non-functional regression testing will check if addition or revision of code has caused the application to become unsuitable for use by checking all non-functional parameters.The most common non-functional parameters checked by testers are performance, compatibility, security, usability, reliability, load and stress testing.

Types of Regression Testing

Not all test cases need to be executed again during regression testing. Only the ones for which old code may conflict with new code is rerun. Thus, regression testing has been categorized into seven types.

Here are various types of regression testing that you can use to ensure the current functionality is working as expected and is not affected by any changes in the application.

Let us explore them further to understand the role of each.

1. Corrective Regression Testing

Corrective regression testing involves re-running test cases with absolutely no change in code. It makes the process quicker and the same code can be used repeatedly.

When is it used?

Corrective regression testing is used when there is no change in customer requests or product specifications.

2. Selective Regression Testing

Selective regression testing is the most cost-effective method of regression testing. The aim of selective regression testing is to analyze the impact both old and new codes had on the functionality of the application.

When is it used?

It is primarily used when a block of code has been changed and the testers would like to see the impact of the new code on the old code.

3. Retest All Regression Testing

While talking about retesting and regression testing, regression testing is more than retesting.

This method of regression testing runs all test cases again, even if only minor changes in code have been made. Though time-consuming and expensive, it is a thorough test. Because it checks each and every change the update could possibly have brought on, clients tend to lean towards this method. However, to make the testing process more efficient in terms of both time and cost, it is better to not do this for every single update.

When is it used?

It should be used right at the last leg of testing to get a comprehensive look at all the defects that have been caused by recent updates to the code.

4. Progressive Regression Testing

Progressive Regression Testing entails including new test scenarios and test cases so that the updated version of the software does not impinge upon the previous working features.

When is it used?

It is used when developers have made changes to code or when there have been some major updates in the program specifications.

5. Complete Regression Testing

Complete regression testing advocates that the code should be thoroughly examined before running any further test cases. This is usually applied when there are numerous bugs and the code will require a major overhaul. So if the project owner does not want that, he may order a complete regression testing, so that changes made can simply be restored so as not to alter any major functionality.

When is it used?

This method comes in use when the code submitted has many bugs and defects and will need several fixes and updates.

6. Partial Regression Testing

It addresses the retesting of certain portions of code if changes have been made in the same module. Testers generally employ this on unchanged portions of a module which has been updated. Not only is this efficient in terms of time, but also lets the testers identify and raise crucial bugs in code.

When is it used?

It is generally used when a new block of code has been added to the existing code.

7. Unit Regression Testing

Last but not the least - the most favored method of software regression testing.

Most apps are developed in the form of components or units. Unit regression testing infers to repeating all tests for the unit when a change has been made in it. These tests are run completely in isolation from other test cases from other units, any kind of interaction or dependency.

When is it used?

It is conducted by experienced testers at non-peak hours to ensure the application is completely ready for deployment. Even though other methods may not be mandatory, unit regression testing is a must.

How to Plan Regression Testing for Your Product?

Now the question is, How can I plan to do regression testing in the product? Or How do I do regression testing?

Regression testing in software testing is the final round of testing done by the team after it is deployed and opened up to the market. Thus, it is needless to say that it is crucial for the success of the product and testers need to chalk out a strategy before moving ahead. Following are the two important factors to be kept in mind while designing the strategy:

Let’s bifurcate some concepts around regression testing and understand how to implement regression testing for a product.

• Nature of product

Before designing test cases for the purpose of regression testing, the nature of the product has to be assessed. Testing a simple website and an e-commerce app are vastly different.

For the website, testers need to assess the UI, usability and check small functionalities like entry and acceptance of email ID. Non-functional testing will only be for browser compatibility.

On the other hand, an e-commerce store entails many checks - entry of product, selection and adding to cart, payment and checkout. There are several non-functional tests to run - load testing, stress testing, security testing etc. For example, Indian e-commerce store Flipkart hit quite a snafu during their Big Billion Days as the load crossed a number they hadn’t even imagined to check for.

• Product scale

For smaller products, just a round of manual regression testing may be good enough, but for medium and large ones, automation regression testing is also mandatory.

Strategy for Regression Testing

Through regression testing, testers have to verify that all new and existing functionalities of a software application are working as specified by the client in product requirements. Once all these are met, the product will be ready for deployment. Hence, the process requires careful planning and strategy.

Step 1

Regression testing should be started when the new update is received. The QA team should identify the needs and components of the testing process and proceed to test existing functionalities with the prepared test scripts.

Step 2

Stakeholders, developers and testers should collaborate to prepare a list of all test cases that need to be executed to confirm that the product meets requirements.

Step 3

Entry and exit criteria for test cases should be defined so as to avoid any confusion further on.

Read More : Top 3 Signs You Need a Software QA Process Audit

How to do Targeted Regression Testing?

To make the process of regression testing targeted towards high-risk areas and less time-consuming, we can take a few steps:

• Push smaller releases more often
• Create a model beforehand
• Testers should participate in developer code reviews to understand the code and point out issues earlier
• Pair programming with the developers

Tools Commonly Used for Regression Testing

• Selenium
• Cucumber
• IBM Rational Functional Tester
• TestComplete
• Katalon Studio
• Ranorex Studio

Challenges Faced in Regression Testing:

• To ensure maximum coverage, test suite size needs to be large (that is, number of test cases are very high), causing the process to become costly and slow.
• Recurring regression tests cause the test suite to become larger with each run, again slowing down the process.
• It is very difficult to determine or keep track of how many regression tests have been run.

While all entrepreneurs are very vigilant while choosing the development team, most underestimate the critical factor of hiring a good software testing team. This is exactly what stops their products from hitting the top of the charts.

In a nutshell, regression testing is the process of re-executing functional and non-functional tests to confirm that previously designed and tested software continues to function after a change. Regression testing is one type of software testing used to ensure that a recent code modification hasn't broken current features.

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