Software Testing Tutorial #23 - What is Regression Testing

Summary

This tutorial covers regression testing, a crucial type of software testing performed to ensure that new code, defect fixes, or added functionality do not affect existing features of an application. The instructor explains the differences between regression testing and retesting, providing examples like an e-commerce website's registration functionality. Key topics include when to perform regression testing (e.g., after bug fixes, new features, or code refactoring), techniques for conducting it, and methods for selecting test cases, such as focusing on critical, high-priority, and integration test cases. The video concludes with tips on creating an effective regression test suite.

Takeaways

• 🔄 Regression testing is a widely used software testing type done in every release, especially when a new feature or defect fix is introduced.
• 📜 The purpose of regression testing is to ensure that the existing functionality of an application works as expected after code changes or bug fixes.
• 🔍 Regression testing is different from retesting, though retesting is a part of regression testing. Retesting focuses on verifying fixed defects, while regression ensures overall functionality.
• 🛒 Example: In an e-commerce website, if a Facebook registration bug is fixed, regression testing ensures that other registration options (email, Google, etc.) are unaffected.
• 🔧 Regression testing is necessary when a defect is fixed, new functionality is added, or code refactoring is done to improve performance or maintainability.
• ⚙️ Configuration changes in the application may also necessitate regression testing to ensure no unintended impacts on existing functionality.
• 💡 Techniques for regression testing include selecting all test cases, selecting specific test cases based on impacted areas, or prioritizing critical test cases.
• 📊 Critical, frequently used functionalities should be included in regression testing to ensure core application features work post-changes.
• 🧩 High-priority test cases and integration test cases should be part of regression test suites to cover key aspects and integrations of the application.
• 🔄 Test case selection should consider the module being changed, analyzing which parts of the application may be impacted and adjusting the regression test cases accordingly.

Q & A

What is regression testing in software development?

Regression testing is a technique used to ensure that existing functionality of a software or application works as expected after new code, bug fixes, or additional features have been introduced.

How is regression testing different from retesting?

Regression testing ensures that new code changes do not negatively affect the existing functionality, while retesting focuses on verifying whether specific defects have been fixed. Retesting is a part of regression testing, but their purposes differ.

When should regression testing be performed?

Regression testing should be performed after any defect fix, new functionality addition, code refactoring, or configuration changes to ensure that the existing functionalities are not impacted by these changes.

What is an example of regression testing in an e-commerce website?

In an e-commerce website, if a developer fixes a bug related to registration via Facebook, regression testing would involve checking other registration methods (e.g., via email or Google account) to ensure they were not affected by the Facebook registration fix.

What are the main techniques for conducting regression testing?

The main techniques for regression testing include: 1) selecting all test cases, 2) regression test selection (choosing only relevant test cases), and 3) prioritizing test cases based on critical functionality.

What is the 'regression test selection' technique?

Regression test selection involves analyzing which parts of the application are impacted by a change and executing only the test cases related to those modules, instead of running all test cases.

Why is selecting all test cases for regression testing uncommon in manual testing?

Selecting all test cases for regression testing is uncommon in manual testing because it requires significant effort to manually execute all test cases. This approach is more feasible when there is a fully automated regression suite.

How does prioritization help in regression testing?

Prioritization helps by allowing testers to focus on the most critical functionalities of an application, ensuring that essential features are thoroughly tested after any change.

What are some key criteria for selecting regression test cases?

Key criteria for selecting regression test cases include frequently used functionalities, high-priority test cases, integration test cases, and module-specific test cases.

What is the role of integration test cases in regression testing?

Integration test cases play a crucial role in regression testing by ensuring that the application continues to function properly with external systems and other integrated components after any code changes.

Outlines

00:00

🔍 Introduction to Regression Testing

This paragraph introduces regression testing, describing it as one of the most widely performed testing types in software projects. It highlights that regression testing ensures that existing functionality continues to work correctly after code changes, new feature additions, or defect fixes. A key distinction is made between regression testing and re-testing, with regression testing focusing on the overall application’s behavior while re-testing is a part of it. The need to understand both concepts from an interview point of view is emphasized.

05:00

🛠️ When to Perform Regression Testing

This section discusses various scenarios where regression testing is needed. The first scenario is when a defect fix has been applied, requiring verification that the fix hasn't affected other areas of the application. Another situation is when new functionality is added, such as features or code refactoring to improve performance. Each scenario involves ensuring that the application’s functionality remains unaffected by the changes. The importance of selecting test cases for critical areas and configuration changes is also mentioned.

10:02

📋 Regression Testing Techniques

The paragraph explains different techniques for performing regression testing. One method is to execute all test cases, although this may be impractical without an automated suite due to the manual effort required. Another approach is regression test selection, where testers analyze the affected modules and select specific test cases based on impact. Prioritization of test cases is the third approach, where critical tests are executed to ensure the stability of the key application functionalities. Developers’ input is crucial in determining impacted areas.

15:04

🔍 How to Select Regression Test Cases

This section focuses on criteria for selecting regression test cases. Frequently used functionalities and high-priority test cases are highlighted as critical for inclusion in regression suites. The importance of testing integration points in applications that interact with other systems is also emphasized. Test case selection can also be based on module analysis, where impacted areas of the application are identified and corresponding test cases are selected for regression testing. These techniques help ensure that any changes to the application do not affect existing functionality.

📝 Final Thoughts on Regression Testing

The concluding paragraph summarizes the importance of regression testing in ensuring application stability after code changes, defect fixes, or the introduction of new functionalities. It revisits the strategies for selecting test cases and highlights the need for continuous analysis of the application to ensure proper regression coverage. The video concludes with a reminder to share and subscribe, thanking viewers for watching the tutorial.

Keywords

💡Regression Testing

Regression testing is a type of software testing performed to ensure that new code changes do not negatively impact the existing functionality of an application. It is carried out whenever new features are added, defects are fixed, or configuration changes are made to ensure that everything still works as expected. In the video, regression testing is highlighted as a key testing type done in almost every software release.

💡Retesting

Retesting refers to testing the specific functionality or defect that was fixed, to ensure the issue has been resolved. While retesting is sometimes seen as part of regression testing, it is different because it focuses only on the defect or change being fixed. In the video, it is explained that while retesting may occur during regression testing, their purposes are distinct.

💡Defect Fix

A defect fix is the process of addressing and resolving bugs or errors in a software application. When a defect is fixed, regression testing is needed to verify that other parts of the application haven't been negatively affected. The video uses the example of fixing a registration issue in an e-commerce website to show how defect fixes trigger the need for regression testing.

💡New Functionality

New functionality refers to additional features or capabilities added to a software application. Whenever new functionality is introduced, regression testing is necessary to ensure the new changes do not interfere with existing features. In the video, the introduction of new registration options on an e-commerce website is used as an example.

💡Code Refactoring

Code refactoring involves restructuring existing code without changing its external behavior to improve performance or maintainability. Regression testing is performed after refactoring to ensure that the changes have not broken any part of the software. In the video, it is mentioned as one of the reasons regression testing is essential.

💡Test Case Selection

Test case selection is the process of choosing specific test cases to execute during regression testing. This selection is based on the areas of the application impacted by code changes. In the video, different strategies for test case selection, such as selecting all test cases or a subset of critical ones, are discussed.

💡Prioritization of Test Cases

Prioritization of test cases involves ranking test cases based on their importance to the application's core functionality. High-priority test cases are executed first to ensure that critical features are functioning correctly. In the video, prioritization is mentioned as an approach to manage regression testing when time or resources are limited.

💡Frequently Used Functionalities

Frequently used functionalities refer to the core features of an application that are commonly accessed by users. These are often prioritized during regression testing because any defects in them could severely impact the user experience. In the video, selecting test cases for frequently used functionalities is recommended for effective regression testing.

💡Integration Test Cases

Integration test cases are tests that verify if different modules or components of an application work together as expected. In regression testing, these are critical to ensure that changes in one module do not break the interactions with other modules. The video emphasizes the importance of including integration test cases in regression testing, especially in complex applications.

💡Configuration Changes

Configuration changes refer to adjustments made to the software's environment or settings that do not involve changes to the actual code. Regression testing is necessary to ensure that these changes have not affected the application's functionality. The video lists configuration changes as one of the scenarios when regression testing should be performed.

Highlights

Regression testing is one of the most widely done types of software testing, used in nearly every release.

Regression testing ensures that the existing functionality of the software works as expected after new code is introduced or defect fixes are applied.

Regression testing is different from retesting, although some retesting is included within it.

Regression testing verifies that other functionalities, not directly related to the fix, are still working correctly after a defect fix.

An example is given using an e-commerce website, where a defect in the registration process using Facebook login could affect other registration methods.

Regression testing may involve a complete set of test cases, or only a subset depending on the changes made.

The key times to perform regression testing are after defect fixes, new feature additions, and code refactoring.

Regression testing can be triggered by configuration changes, which might affect the application's overall functionality.

There are several techniques for regression testing, including executing all test cases or selecting only those affected by the change.

Regression test selection involves analyzing the areas of the application affected by the changes and testing only those parts.

Prioritizing test cases for regression testing focuses on critical functionalities that are frequently used or most essential to the application.

Regression test cases can be chosen based on frequently used functionalities, high-priority test cases, and integration test cases.

In some situations, you select test cases based on modules affected by the changes, analyzing which modules may have been impacted.

Automated regression testing can significantly reduce manual effort and allow for re-execution of test cases across multiple releases.

The goal of regression testing is to ensure the software's integrity after modifications and maintain consistency in its performance.

Transcripts

hello everyone welcome again in the

software testing tutorial

we are going to learn what is regression

testing

so regression testing is

the most widely done you know software

testing type in any software testing

project

because this is the testing that you

will be

doing in mostly every release and every

you know new feature being added or

defect fix

being added so before we get into the

details let's first understand

what exactly regression testing is so if

we talk about the definition regression

testing

is the technique or the testing type

which is performed to ensure that the

existing functionality

of the software or application works

as expected if there is any new code

introduced or

new defect fix has been done or any new

functionality added in the application

so please note that regression testing

is uh you know different from retesting

so retesting is

sort of you know you can say it's a part

of regression testing

but there is a very fine difference

between regression testing and

re-testing right so you need to

understand from interview point of view

that regression testing is not same

as re-testing but in regression testing

you

do some re-testing so you can say there

are

you know some re-testing or the test

case that you execute as part of

regression testing

are the test cases that you are actually

retesting

but the definition and the purpose of

regression testing and retesting

is completely different so let's first

understand

what exactly regression testing is and

when you do it how you do it

what are the different strategies or

techniques that you use to do

regression testing now let me take an

example to explain you

exactly what regression testing is so in

terms of definition

we know that any you know testing

that you perform if there is any bug fix

or

code changes or new functionality

addition into the software

that you know set of test cases that you

execute is

the regression testing now say for

example if i take an example of the

e-commerce website so e-commerce website

will have the register functionality

right so that is the example that we

have been taking till now

now in the registration page

say for example there is a register

link and once the user clicks on a

register link

he has the option to register using

email using facebook account using

google account and

other social media accounts right so in

the register

module there are many different

options basically or different

implementation

to register a user on the particular

website or

e-commerce website now when the user

registers on e-commerce website

then in that particular case if there is

any change say for example you are

testing the registration functionality

and

during the testing of the registration

functionality

with the facebook registration or

registration using facebook login id

the registration fails or registration

is not successful

so that is the defect that you found

during the functional testing

now when the developer is fixing that

particular

defect then in that case

that fix could impact other registration

functionality as well in the application

right so

when the defect of registration got

fixed then in that

case what you need to do is you need to

basically

verify that other registration

functionality is also working as

expected

now when you are verifying the

other registration functionality or you

are testing

the registration functionality using

email using google

account as part of the defect fix that

was fixed

for the facebook account then those

test cases that you execute as part of

this defect fix

are known as regression test cases right

or regression testing

now regression testing is not limited

only to

that set of test cases it could be a

complete set of regression test cases so

in this particular case

if say for example you want you can test

the overall critical functionality of

the whole e-commerce website

because there has been a fix that is

done

um within the application so there are

different techniques that can be chosen

to do the regression testing

so this is a brief introduction and what

exactly irrigation testing

is and when you should do regression

testing

now let me first understand ah you know

what all

scenarios could be there when you can

perform regression testing right

so let me say when you can do regression

testing

so if i talk about when so the first

example that we took

is when the defect fix happened

right so in the case of defect fix so

when we say defect fix

defect fix will be done when there is a

code fix right so if there is any defect

there could be another code fix or there

could be configuration

changes that could fix that defect right

so in case of defect fix

there will be the need of the regression

testing okay

and the second option could be

new functionality that's right so new

functionality added

so new functionality functionality or

feature

being added into the application so that

could be the second case

third case could be code refactoring

right so code refactoring wherein

developers

or the development development team

refactors the existing code to improve

the performance

or improve the maintainability of the

code

then in that particular case the overall

structure

or the code is being refactored in that

case

you need to pick a set of test cases

that are

critical for that application and are

basic to that particular application

and ensure that the application

functionality has not been impacted

because of

code refactoring or because of adding

the new functionality or

because of you know having the defect

fix in the application

so any you know verification that you do

to ensure that the existing

functionality of the application

because of you know defect fictional

functionality code refactoring there

could be n number of you know other

factors as well

um and ensure that the existing

functionality of the application works

as expected

then that is regression testing and

these are

you know some of the places when you do

regression testing there could be you

know like this is not the comprehensive

list there could be many more factors

when you choose to do regression testing

uh other i can think of

is say for example configuration changes

right so config changes

so if there are any config changes in

the application

then in that case as well you do

regression testing

so this is one part of the regression

testing so when you do the regression

testing

um now if i talk about the techniques of

the regression testing so let me say

techniques let me rub this and

in the techniques so

so in the techniques of regression

testing what you can do is say for

example

there is a defect fix that we have seen

in the e-commerce portal

so in the techniques you can

first technique will be you can select

all the test cases right so you can

select

all um the test cases that existing test

cases for the application so in the

e-commerce

portal whatever test cases you have

written till now

say for example whatever functionalities

have been you know implemented

you can select all the test cases and

execute all those test cases

so that could be one of the technique or

approach to

do the regression testing in case of any

fix or any new

uh you know functionality being added

but this is

this is very highly you know unlikely

unless you are

having 100 automated regression test

suite

because it will require a lot of manual

testing effort to do the

you know complete regression test after

each of the defect fix because you have

to re-execute say for example

till release 2 you have written 100 test

cases

then with every defect fixed you have to

basically re-execute those handed test

cases

right or with any new functionality

being added you have to re-execute those

100 test cases if you do select all or

you select all the test cases

the second technique you can use is

basically

you know regression

test selection okay so in this case

what you do is you basically see what

area of the application has been changed

now in this

in in the previous example we have seen

the registration functionality

so in the registration functionality

only

the registration with facebook was

failing say for example right

now that fix has been done

in the register okay so in the

registration

pardon my handwriting just

let me change it okay so in the

registration

only the facebook registration defect

has been fixed

fixed so what you can do is when you

choose this particular technique so what

you do is you

you select the test cases that you want

to

execute or basically you analyze the

modules that could be impacted

because of that particular fix so now we

see registration functionality

uh is you know related uh so we'll test

all the registration test cases with

different you know

social media account and email account

and we'll also

test the login functionality along with

that right so you can have a subset of

test cases you can select the subset of

test cases

based on your analysis of the module

that has been

changed or updated by the developer

and developers if you talk to developers

they'll help you out

about the impact or the changes that

they have done in the code which will

help you to analyze

which test cases you need to basically

re-execute when you

when you select uh the test selection

for the regression

the third approach will be uh basically

you prioritize the test cases right so

prioritize

so in the prioritize test cases

what you do is you prioritize the

critical test cases of your application

okay so when say for example your

application is already in production

and all the major functionality or the

critical functionality that is being

used

uh you know every day so those test

cases

will be prioritized and in case of any

functional changes any defect fixes

those prioritized

test cases will be executed as part of

the regression

testing right so these are some of the

techniques that you'll utilize to do the

regression

testing now when we talk about you know

how you can select the regression test

cases

so let me explain how part of the

regression testing as well

so how to select

how to select tests all right

now to understand how to select

regression test cases what you need to

understand is basically say for example

first thing is to

say frequently used functionalities

right

so frequently used functionalities

so this is one of the criteria that you

can utilize to

identify your regression test cases so

in the project when you're working you

will have

the prioritized um

you know functionalities or the critical

functionalities that are used very

widely by the

by the end user or by the customer then

if

those are the used functionalities or

the frequently used functionalities

then those functionalities or any test

cases related to this

that functionality will have the test

cases those test cases will be critical

for your regression testing and you need

to pull out those test cases

and have those into your regression test

suite

so this is the first you know approach

that you can use to select

the test cases so critical functionality

pull out the test cases for those

critical functionality

uh in your application the second is

basically

high priority so based on uh the

priority so high priority

so if you have you know the test cases

you will have the priority

assigned to those test cases so second

approach is

uh in case of any changes or new

functionality or new

uh implementation new feature being

added into the application

you pick all the higher priority test

cases that

you already have and you allocate those

as a regression test suite and execute

those

the third criteria could be your

say for example integration test cases

right

so integration test cases are uh you

know another

very important test cases because when

you have the application it will be

integrated with other n number of

applications and if there are any

updates in the application you want to

ensure

that all the integration points are

working as expected

so this is another criteria to pull out

the regression test cases

so these are some of the key criteria

that you can utilize to pull the

regression test cases and create your

regression test suite

and make it ready to be executed when

whenever there is a you know

defect fix or new functionality added

right uh the third

the the next one could be you know say

for example

select test cases as per module so as

per module

so when you when you do this so when you

select as per module

then in that case same example uh login

functionality so in that case

you analyze what fix has been done in

the software application

and based on that change you

analyze the module and see what all

changes have been done

which all modules could have been

impacted and you

make the selection of the test cases

based on that

change in the module right so this is

you know this could be another

criteria to select the test cases so

these are some of the criteria but when

you start you know working in

in the project and you will start to

analyze

analyze the overall you know application

and how to figure out the test cases

there

could be you know like another and

number of you know selection criteria

that you will come to know

but these are some of the very commonly

asked

criterias and very widely used criteria

is basically

to pull out the regression test cases

and

verify the regression uh that the

application is working as expected in

case of any

you know changes to the code because of

bug fix or functionality changes or

addition of the

new requirement or implementation of the

new requirement in the

application so that is all about

basically what is regression testing and

you know when

to perform regression testing we have

covered some of the techniques

of regression testing and then how you

can select the regression test cases

uh and ensure that your application

works as expected

if there is any you know new code

introduced into the application because

of defect fix

or any other changes into the

application

so that's all for this tutorial hope it

was helpful

please do share and subscribe and thank

you very much for watching