Understanding the difference between regression and functional testing helps teams optimize test coverage, functional testing checks what’s new, while regression testing ensures nothing old is broken.

2. Understanding the key Functional vs Regression Testing
differences helps QA teams choose the right testing approach for
each development stage.
Testing is frequently overlooked or not given the same importance as
development in the software development lifecycle.
However, it is just as crucial as development because a buggy
application with multiple features can cost you money and a user
base. Both Regression Testing and Functional Testing are an essential
part of test automation in DevOps.
What Is Functional Testing?
Functional testing is a software testing approach that evaluates all of
the software’s features/functions to ensure that each component
meets the required specifications.
Each application function or piece is thoroughly tested to ensure that
the output/result provided by each application function is as expected.
Function functions are tested by feeding input and verifying output to
check what the system does. APIs, databases, security, user
interfaces, client/server applications, and the functionality of the
Application Under Test are all checked during the testing.

3. Functional testing does not usually consider internal structure,
code, performance, or environmental factors.
The primary aim of functional testing is to ensure Usability,
accessibility, and compliance with requirement specifications. In
addition, it provides that a product or application will work correctly
and efficiently for users.
What do you test in Functional Testing?
Mainline functions: Test an application’s primary functions.Basic
Usability entails testing the system’s Usability on a fundamental level.
For example, it determines whether a user can freely navigate the
screens without difficulty.
Accessibility: Verifies that the system is accessible to the user.
Testing Techniques to Check for Error Conditions: Using testing
techniques to check for error conditions. It examines whether the
appropriate error messages are displayed.
To ensure the validity of the functionality of an application program,
functional testing employs a black box testing approach. Because the
emphasis is on functionality, the design and user experience aspects
are unaffected. The following are the main aspects of functional
testing.
Analyze Needs of the Customer:

4. ●​ Validation of the input data
●​ Getting the expected outcomes
●​ Execution of the test case
●​ Comparison of the actual and anticipated outcomes
●​ Comparing the results of the test cases
Why Do You Need To Perform Functional Testing?
The importance of functional testing in validating the quality and
functionality of the software cannot be overstated.
Quality assurance teams use this software testing technique to verify
software functionality based on the Software Requirements
Specification (SRS) and ensure the system functions according to
user specifications.
This type of testing aids in determining whether the system is ready
for release and error-free. This testing does not rely on assumptions
about the system’s structure, but it ensures that a high-quality product
is delivered.
Essentially, this testing method is used to test usability features,
specific error conditions, accessibility features, and other essential
software functions.
It is very easy to dismiss software testing as a waste of time and
money. However, a minor bug spiraled out of control for so many

5. organizations. Embarrassing software flaws in a product may
cause a brand to go viral but in the wrong way.
There is no need to learn the importance of proper software testing
techniques the hard way.
Best Practices For Functional Testing:
#01 Plan Of Testing And Test Cases
The goals and scope of testing, the number of people who will be
involved in the testing, the hardware, and software tools that will be
used in the testing, the testing schedule, and the number of test cases
that will be written to perform the testing are all part of the planning
process.
The input data for test cases are based on the functionality’s
specification. These test cases should be organized and prioritized to
reduce delay and risk. Finally, the development team should review
these test plans.
#02 Execution Of Test Cases Should Be Well-Planned.
Testing specific workflows in your app is known as test execution.
Functional testing depends heavily on this.

6. Your testers can use test execution to work their way through
specific functions for your mobile or web app, ensuring that they
work as they should within the pre-planned workflow.
Assume you’ve created a test case for your e-commerce app. You
want users to be able to search for red trainers,’ click on a specific pair,
add it to their shopping bag, and check out. Within each step, testers
will test specific functions such as the search bar, card payment, and
shopping bag to see if the expected results are obtained.
#03 Reporting Of Test Results
A test result report follows a specific format and includes a summary
of all test cases completed, the time spent at each stage for each
feature, and its status and progress.
It also contains information about any new defects discovered during
testing.
Overall, the test result report should be presented clearly and simply
so that the development team can understand it.
#04 Automating Functional Testing
Automated testing improves the product or software’s quality while
also saving time. What should be automated is up to the tester to
decide.

7. Automated testing is slightly more expensive in the short term, but
it is more beneficial to the product in the long run. Avoid
automating things that can be done more cheaply and effectively by
manual testing.
#05 Manage Defects With Data Storage System
Many people working on the same functionality may result in
duplicate defect reports, incorrect order of issue resolution,
consideration of incorrect defects, and other issues. A centralized
data storage system that everyone can access should be managed to
prevent this.
The system includes standard templates for defect reporting and
verification, a priority ranking of defects, and information about task
assignments; this aids in the solution of problems one at a time.
Different Functional Testing techniques:
End-user-based tests: In this functional testing technique, the system
is tested to determine whether or not all of the components work
perfectly together.
●​ Equivalence tests: The test data is divided into various partitions
in this equivalence test technique, and the data in each partition
must respond similarly. Thus, tests are run on a single condition;

8. if any of the conditions in any partition fails, the others stop
working.
●​ Boundary value tests: This technique helps validate how the
system performs when boundary data limits are used. In most
cases, if the provided inputs are less than the boundary values,
the test is considered harmful.
●​ Decision-based tests: This decision-based testing technique aids
in validating the possible outcomes that can be obtained when a
specific condition is met.
●​ Ad-hoc tests: This testing technique aids in identifying bugs that
were missed in previous tests. Ad hoc testing is an effective
method for identifying bugs that were not previously identified.
What is Regression Testing?
Regression testing is the type of testing which ensures that changes
made to the codebase do not affect existing software functionality.
These code changes could include, for example, adding new features,
fixing bugs, or updating a current feature.
In other words, regression testing entails re-running previously cleared
test cases against the new version to ensure that the app’s
functionalities are working properly. Furthermore, regression testing is
a series of tests, not a single test run whenever new code is added.

9. Coders create test scenarios and exercise to put newly written code
to the test. These tests are included in the ‘test bucket.’
Before releasing a new product version, old test cases are run against
the new version to ensure that the old functionality remains intact.
This is because adding new code can sometimes introduce errors in
the existing code.
Regression Testing frequently entails selecting a subset of all
previously executed tests to run again.
●​ Because of changing requirements, the code has been modified.
●​ Software is updated with new features.
●​ Following the correction of defects.
●​ Patch to address a performance issue.
●​ Significant modifications.
●​ Configuration changes.
When To Perform Regression Testing?
It should be taken up when new functionality is introduced: It’s one of
the most crucial steps in the regression testing procedure.
When developers submit new code, they don’t always pay attention to
how it interacts with existing code, so software regression testing
should be used to identify any potential problems.

10. Existing functionality has been altered based on the requirements,
and developers may revise existing functionality and exclude/edit
some features during the agile software development process.
In such cases, the functionality and regression testing process
determines whether or not the new changes have harmed the rest of
the functionality.
New Integration on Other Products: Regression testing ensures that
the software product continues to perform flawlessly even after
integration with another product.
Why Regression Testing Is Important?
#01 Makes sure that new coding does not interfere with existing
coding features
Regression testing is also necessary to ensure that any new code or
program updates to software do not interfere with the current features
dictated by older code.
For example, when a program or application is updated, software
developers typically use regression testing to assess the viability of
new features and ensure that the new features do not distort the
program’s existing features.
#02 The functionality of the new programming code is evaluated.

11. Regression testing is an essential tool for determining the success
of incorporating new code into an existing program or application.
This is because regression testing is used to test a software program
before implementing new coding and then retest the same software to
ensure that the application retains its functionality even after new
coding is introduced.
#03 Ensures that no defects or bugs remain after software updates
have been implemented.
Regression testing can also be used in quality assurance
assessments by developers to check for any adverse side effects in
the software.
For example, a video game developer, for example, might use
regression testing to evaluate any issues, bugs, or glitches that arise
after introducing new gaming code into an application. So, for
example, suppose there are any bugs or issues with the program.
In that case, the developer can make the necessary changes before
retesting the application to ensure that the problems have been
resolved.
#04 Allows for the retesting of existing software following application
changes.

12. Regression testing is also vital for providing additional test
executions to ensure the viability of program code changes.
Retesting each case following a software update or modification
enables developers to assess how the new changes affect the
program.
For example, suppose a software developer tests a software program
after initializing new program code and discovers that the new
features disable existing features.
In that case, the developer may retest the update each time they make
a repair or change to it. Retesting allows the developer to pinpoint the
source of the problem and reconfigure the program to run at peak
performance.
Regression Testing Tools:
Developers can choose which tools to use to successfully execute the
process after selecting test cases to perform regression testing on.
Common regression testing tools can include the following,
depending on the project:
●​ Functional regression testing tools: Enable developers to test
individual software program elements for errors or defects and
generate a report to aid future development.
●​ API testing tools: API testing, also known as application
programming interfaces, allows developers to set input criteria

13. to ensure that the software’s output meets performance
expectations.
●​ Unit regression testing tools: Enable developers to evaluate
specific code elements within a software program to ensure the
highest quality and functionality of each code that is integrated
into the application.
Challenges of Regression Testing:
When starting regression tests, several challenges may arise. For
example, depending on the test case, it can be challenging to start
regression testing every time a program changes while staying within
the project scope and budget.
Furthermore, continuous regression testing can create large test
suites that require more resources to complete on time.
A database is created during each test case to store all data related to
that test case. In addition, consistent regression testing can
necessitate the generation of large amounts of data, resulting in
ever-expanding test suites.
This factor may challenge regression testing of entire test suites,
depending on the project budget and scope. Outlining the frequency
with which to perform regression testing can also be challenging.

14. For example, developers may choose to perform regression testing
every time software modifications are integrated or only after errors
or defects are repaired.
However, building large test suites can necessitate additional
resources, and frequent regression testing can also require additional
resources.
Difference Between Functional Testing And Regression
Testing
Many teams often confuse functional testing vs regression testing,
but both serve distinct purposes in maintaining software quality and
performance stability.
#01 Feasibility of Automation
Functional testing is performed manually at first, and once a feature is
stable, test cases are automated. However, only those test cases that
are already stable are executed manually or automatically during
regression testing, so this can be automated when needed.
#02 Maintenance/Modification Of Test Script
Because functional test cases are few and focused on a single
feature, they do not require extensive modification.

15. Test scripts in the regression suite, on the other hand, require more
maintenance because the test suite is designed to test overall
functionality.
However, there is a possibility that it contains old test cases. In
addition, functionalities that have changed, new features that have
been added, or some features that have been removed may be
included in test cases.
#03 The Goal Of Testing
Functional testing determines how closely the developed application
matches the desired requirements.
The purpose of regression testing, on the other hand, is to ensure that
any changes to the application or systems have not resulted in code
breaks and that the system continues to function properly.
#04 Test Case Executed
The functional testing test suite includes a new set of cases and
functionalities that have never been tested or executed before. The
test cases are re-executed when a defect is raised against a
requirement.
Following that, it is fixed and assigned for retesting. If the fault is
closed during retesting, the previously failed linked test cases pass.

16. Cases that have previously been tested and passed are included in
the regression suite.
Regression testing entails re-running test cases to ensure that
changes have not affected previously tested features.
#05 Scope of Testing
Because functional testing is feature-specific, it has a limited scope.
For example, suppose a team creates a car with a specific navigation
feature. In that case, testers will ensure that the quality can locate the
vehicle on a map and guide the driver to any desired destination.
Regression testing, on the other hand, is not feature-specific. It is
carried out after a bug has been fixed, changes to a feature have been
made, or a new feature added to an existing software application. So
let’s look at the same navigation feature we discussed earlier.
Regression testing will be carried out if the mechanic has resolved
some issues. If, for example, the navigation feature was not turning on
and the mechanic fixed the problem, testers will ensure that it works
and that everything else in the car works properly.
Regression testing entails testing a product from beginning to end,
whereas functional testing is concerned with determining whether or
not a single feature works.

17. #06 Acceptance Criteria
Functional testing determines whether or not a feature works and
whether or not it works as expected.
When a new feature is added to an application, it is supposed to work
and is also supposed to work efficiently. This is known as a feature’s
acceptance criteria, and functional testing is used to test that feature.
Regression testing has to consider the acceptance criteria for several
features instead of just the single added, updated, or fixed element.
This happens because when a new feature is implemented, or a bug is
fixed, the fix may affect another component of an application.
Thus, the acceptance criteria for that feature will no longer be fulfilled,
and this can only be determined if a tester looks at the acceptance
criteria for all features caused by the change.

18. Conclusion:
To ensure a product’s stability, QA teams use functional testing and
regression testing.
When the regression testing cycle is run after a change is made to the
code and new bugs are discovered, the test engineers learn how a
code change in one component of a product affects the code in the
other components. It also aids engineers in developing new features
because they are aware that certain parts of the code rely on others.
Not when bugs are fixed, but when new features are implemented, it is
critical for teams that are still figuring out which features rely on each
other to deliver a functioning product.
Previous test results assist teams in planning future testing cycles
and highlighting areas that should be tested when a new feature is
added. When compared to functional testing processes, regression
testing has a broader scope.
However, if a product has gone through multiple cycles, teams can
estimate the impact of change and plan further testing.
For more details, readers may also refer to TestGrid.