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Difference Between Regression Testing and Functional Testing

What is Functional Testing?

Before we jump into the main topic which is “Difference Between Regression Testing and Functional Testing”, let’s understand the defintion of functional testing. When running functional tests, quality assurance engineers can use the functional or requirement specifications to help define what they consider to be acceptable. The quality assurance engineers have a document that contains these specifications, which instructs them on the steps they need to take in order to evaluate the software system’s conformance. They can also be asked to conduct tests on particular business-side scenarios using this document, which will provide a picture of the system as a whole. As a result, we realise that quality assurance engineers have two options for conducting functional testing:

  • Requirements-based functional testing: Instructions on validating the functional areas of the software system can be found within this method.
  • Business scenarios-based functional testing: This method provides directions for validating the software system in accordance with various business scenarios.

A sort of software testing called functional testing makes sure that a software system operates in line with the specifications that were given to it. This test’s main goal is to verify how well the application’s software functions by simulating user input and assessing the system’s reaction in light of predefined standards. This test does not focus on the application’s source code and instead focuses primarily on black box testing. It examines the application’s APIs as well as its security, client-server communication, database, user interface, and other functionalities. Testers have the option of conducting functional tests manually or through the use of automation.

Also read: Difference Between Structural Testing and Functional Testing (technosuggest.com)

What do you test in Functional Testing?

The primary purpose of functional testing, which is performed by testers, is to validate the capabilities of the software system. This testing will primarily focus on the following areas:

  • Accessibility: runs accessibility tests on the system to determine whether it complies with accessibility standards.
  • Conditions for Errors: Whenever an error occurs, the system typically outputs a helpful error message. This test verifies that your system is functioning properly and generates the necessary error messages for troubleshooting.
  • Mainline functions: If the system’s primary functions are ineffective, it is useless. To make sure that doesn’t happen, testing is conducted.
  • Basic Usability: The test performs a usability test to confirm that users can easily navigate your system.

Also read: Usability Testing vs User Testing: Explained! (technosuggest.com)

Process Workflow for Functional Testing

A functional test’s workflow consists of three steps. As follows:

  1. Create input values
  2. Execute test cases
  3. Compare the actual output with the expected result.

Functional testing typically proceeds in the manner described below:

  1. Identify the component of the software system that needs to be tested by the testers. Error conditions, product usability, message types, and central functions are some examples of the many facets and functionalities that may be involved.
  2. Construct the input data in accordance with the particular requirements for the functionalities that need to be tested.
  3. Determine which output parameters are acceptable by referring to the requirements that have been outlined and which ones are not acceptable.
  4. Carry out test cases.
  5. Finally, you should contrast the output that was expected with the result that actually occurred during the test. Monitoring this will reveal whether or not your software system is functioning properly.

Advantages and Disadvantages of Functional Testing


  • This test attempts to replicate the product in its intended setting, which is a live environment. The operating system, browsers, system specifications, and other elements are the primary focus of this test.
  • It does not consider hypothetical situations and instead deals directly with the structure of the system.
  • Using this testing methodology, companies are able to provide customers with products of a high quality. It gives them the ability to fulfil the requirements of their customers and guarantees that they will be satisfied.
  • This test assists organisations in delivering a product that is both bug-free and satisfies all of the requirements outlined by the customer.
  • The use of risk-based testing guarantees a reduction in the likelihood of risk.


The performance, the throughput time, the responsiveness, and other factors are not taken into consideration in this test; however, it does ensure that the product meets the requirements of the customer. In order to evaluate the product’s overall quality, it is necessary to look at these aspects. In addition, functional testing does not take into account important factors such as the amount of time required to carry out particular functions, the level of safety offered by the application, and other components. Even though functional testing is essential, it cannot validate whether or not an application is prepared for use in the real world.


  • Testers frequently wind up carrying out redundant tests.
  • It is possible for testers to miss logical flaws in the product.
  • Since testers conduct this test in accordance with the requirements, it may take a while if the testing requirements are vague or complex.

What is Regression Testing?

We also need to understand the meaning of regression testing before we dive into the main topic which is “Difference Between Regression Testing and Functional Testing”. This testing ensures that changes made to the codebase do not affect the functionality of the software that is currently in use. These modifications to the code might include, for instance, the addition of new features, the correction of bugs, or an update to an existing feature. To put it another way, regression testing entails re-running test cases that were previously cleared against the new version in order to guarantee that the app’s functionalities are functioning appropriately. In addition, when new code is added, the regression testing process involves running a series of tests rather than just one test.

In order to validate recently written code, coders devise test cases and carry out related exercises. The ‘test bucket’ also contains the results of these examinations. Before a new product version is made public, the older test cases are executed against the new version to guarantee that the previously available functionality has not been compromised. This is due to the fact that adding new code can occasionally cause errors in the code that already exists. Regression When testing, it is common practise to choose and re-execute only a subset of all of the previous tests that were carried out.

  • The code has changed as a result of evolving requirements.
  • Configuration changes.
  • Software updates include new features.
  • subsequently to the rectification of flaws.
  • Patch to fix a performance problem.
  • substantial alterations

When To Perform Regression Testing?

It needs to be addressed ASAP after new functionalities are added: In the process of regression testing, this step is among the most important and fundamental ones. Because developers don’t always pay attention to how new code interacts with existing code when they submit it, software regression testing should be used to identify any potential issues. The existing functionality has been modified based on the requirements, and during the agile software development process, developers may revise the existing functionality and exclude or edit some features. In such circumstances, the process of functionality and regression testing is utilised to determine whether or not the newly implemented changes have negatively impacted the remaining functionality. Other Products Now Featuring New Integration: Performing regression testing on a software product ensures that it will continue to operate without error even after it has been integrated with another product.

Why Regression Testing Is Important?

1. Ensures that newly added code will not cause interference with previously added features of coding

It is essential to conduct regression testing in order to ensure that the addition of any new code or programme updates to software does not compromise the functionality of the previously established features. For instance, when a programme or application is updated, software developers will typically use regression testing to evaluate the viability of new features and ensure that the new features do not distort the program’s existing features. This is done to ensure that the programme continues to function as intended.

2. The usefulness of the newly written code in the programming language is examined.

Testing for regression is an essential instrument for determining whether or not it was successful to incorporate new code into an already existing application or programme. This is due to the fact that regression testing is used to test a software programme prior to the implementation of new coding, and then the same software is retested to ensure that the application maintains its functionality even after the implementation of new coding.

3. Ensures that after software updates have been implemented, there are no errors or bugs left in the system.

The purpose of using regression testing in quality assurance evaluations conducted by developers is to check for any unintended side effects that may be present in the software. A developer of video games, for instance, might use regression testing to evaluate any issues, bugs, or glitches that emerge after introducing new gaming code into an application. This could be done, for instance, by using a video game as an example. Take for instance the possibility that there are some errors or problems with the programme. If this is the case, the developer can make the necessary adjustments to the application before retesting it to ensure that the issues have been fixed.

4. Allows for the retesting of previously installed software after changes have been made to the application.

In addition, providing additional test executions to ensure the viability of programme code changes is an essential part of the role that regression testing plays. Retesting each case after a software update or modification enables developers to evaluate how the programme is impacted by the new changes. Take, for instance, the scenario in which a software developer tests a programme after initialising new programme codes and finds that the newly added features disable features that were previously present in the programme. If this is the case, the developer may choose to retest the update after making any necessary repairs or adjustments to it. The developer is able to zero in on the specific cause of the issue and rework the programme so that it operates at its full potential after it has been retested.

Challenges of Regression Testing:

When beginning regression testing, you might face a few different challenges. For instance, it may be difficult, depending on the test case, to begin regression testing each time a programme undergoes changes while simultaneously adhering to the project’s scope and remaining within its allotted budget. In addition, continuous regression testing can result in the creation of large test suites that call for an increased amount of resources to finish on time. For the purpose of storing any and all information pertinent to a given test case, a database is generated for each test case. In addition, performing consistent regression testing can make it necessary to generate large amounts of data, which can lead to test suites that are constantly growing in size.

Depending on the budget and scope of the project, this factor may present a challenge for regression testing of the entire test suite. It can also be difficult to determine the frequency with which to carry out regression testing. For instance, developers may opt to run regression tests every time new software is integrated or wait until after errors or defects have been fixed before doing so. However, developing extensive test suites can require additional resources, and performing frequent regression testing can also require additional resources. Both of these scenarios can necessitate additional investment.

Best Practices For Regression Testing:

1. Understanding The Testing Scope

It is essential to have a thorough understanding of the scope of the regression testing process before beginning the process itself because the scope, duration, and objectives of each testing project are unique. If you have a good understanding of the differences in scope, you will be able to plan the execution of your regression cycle more effectively.

2. Automate The Appropriate Test Cases

When properly implemented, automation can provide a significant competitive advantage for a business. Therefore, the first step is to figure out which types of test cases can be automated and which types cannot be. Then, increasing your productivity and saving you time will result from automating the appropriate test cases.

3. Monitor ROI

The return on investment (RoI) is the most essential metric for determining whether or not your campaign for regression testing was successful. The advanced analytics and reports that can be generated by automation tools should be used by quality assurance teams on a continuous basis to monitor RoI. You will be better able to see the reality on the ground and identify areas that need improvement as a result of this.

4. Giving Test Cases A Grade

You have to give each of your test cases a grade if you want to have any chance of being successful with regression testing. After that, you should evaluate various business impacts on the various platforms, compare and track them, and then prioritise the various test scenarios based on the results of those evaluations. You will gain a better understanding of multiple roadblocks, be better able to differentiate between them, and identify them, as well as conduct effective testing based on the requirements.

5. Keeping Up With the Most Recent Regression Suite

In addition to this, you need to stay current with the most recent regression testing suites, just as you would with any other type of technology. Always make sure to take into account both the functional and the non-functional requirements for this purpose. The quality assurance team must remember to always begin with the high-priority and high-value test cases in the suite.

6. Hands-On Knowledge Of Every Change

If you are involved in the creation of software, you should be aware that change is the only thing that is consistent. As a consequence of this, having first-hand experience with each modification is essential.

7. Maintain Regular Communication 

Consistent communication between the developers and the testers to ensure that everyone is up to date on the most recently upgraded version and is aware of any changes that will take effect immediately. They are able to plan their testing ahead of time so that they can remain on schedule for the release of the app or product.

Differences Between Functional Testing And Regression Testing

The following are some distinctions between testing for functionality and testing for regression:

  1. The Aim of Testing

During the functional testing process, it is determined whether or not the feature’s intended purpose in the application meets the requirements of the software. It is done in the beginning stage and checks to see if the users are getting what they expected from the product. On the other hand, testing for regression occurs in the later stages of development. When any new feature or code is added, updated, or improved, it examines the application’s overall stability as well as its functionality to ensure that it has not been affected. It verifies that the updated version of the system does not contain any code breaks or bugs.

  1. Aspects Covered

The following are some of the areas that are covered by functional testing:

  • examining client requirements.
  • test input data.
  • collecting the anticipated outcomes.
  • carrying out the test case.
  • Actual and anticipated results are compared.
  • contrasting the test case outcome.

Regression analysis includes the following elements:

  • Making any new software additions or configuration adjustments.
  • incorporating fresh updates to the structure.
  • Update existing features or add new ones.
  • modifying the current operations.
  1. The test case being performed

In functional testing, the test group is composed of newly created cases and functionalities that are being evaluated. This type of testing is performed on software. These cases have either never been looked into before or have never been looked into more thoroughly. The test cases are executed once more in the event that any defects or bugs manifest themselves in any aspect of the application’s requirements. After that, any bugs that were discovered are fixed, and then the software is tested again to ensure that it hasn’t been compromised in any way. After it has been validated that these issues have been resolved, the test cases will then be incorporated into the application. In a nutshell, when performing regression testing, the test cases are run again to check that the changes have not disrupted the functionality of the features that were previously tested. This is done to ensure that the changes are not a result of the previous testing.

  1. Situations That Require The Testing

Functional testing is necessary for

  • A new system must be put to the test.
  • An application is examined in relation to its features and specifications.
  • ensuring that the module and system integration is flawless.
  • It is necessary to look at the system’s operation as a whole.
  • Determining the system’s workflow.
  • Ensuring that end-to-end flows produce the outcomes that the users have come to expect.

However, regression testing is necessary when

  • The entire codebase is changed as a result of a client change request.
  • A different platform is being used for the backend code.
  • The application gains a new feature or function.
  • There are new patch fixes added.
  • The testing setting has been slightly modified.
  • A developer corrects critical flaws that were discovered by a tester.
  • The application’s user interface has been updated to enhance the user experience.
  1. Methodology Used

Functional testing methodologies include:

  • Black box testing
  • System integration testing
  • White-box testing
  • Interface testing
  • Unit testing
  • Integrating testing
  • Acceptance testing

Whereas, regression testing methodologies include:

  • Component-based testing
  • Aspect testing
  • Database testing
  • Web application testing
  1. Procedure Used

Functional testing is done using the following procedures:

  • determining the functions that will be tested.
  • making data requests.
  • the test cases being run.
  • comparing the results that were produced and the actual results.
  • Test cases that don’t adhere to the requirements are unsuccessful.
  • Then, expectations-based scenarios are developed.
  • changing test scenarios into test cases and submitting bugs for the developer to fix.
  • rerunning the unsuccessful case.

Whereas, regression testing procedures include

  • recognising modified components.
  • putting test cases in order of risk, then testing them.
  • choosing test cases based on the areas that the modification has affected.

Testsigma, Watir, TestingWhiz, Time ShiftX, Appium, KAtalon Studio, IBM Rational Functional Tester, and Selenium are a few of the tools that are used for both functional testing and regression testing.

  1. Automation Feasibility:

Once a feature is stable, test cases are automated after functional testing is completed manually. While only those test cases that are already stable are run manually or automatically during regression testing, allowing for automation when necessary.

  1. Maintenance/modification of test script:

Since functional test cases are fewer in number and more narrowly focused on a feature, they do not require as much modification as other types of test cases. In contrast, the test scripts in the regression suite need significantly more upkeep because the suite itself is designed to test the overall functionality of the product. There is a possibility that it will contain remnants of previous test cases. It’s possible that some of the functionalities in the test cases will have been updated, that some new features will be included, or that some features will have been taken away. In order to prevent the automation scripts from becoming corrupted, the regression suite needs to be updated after each release.


Functional Vs Regression Testing: Key Differences [2023]. (2022, March 25). TestGrid | Blog. Retrieved February 6, 2023, from https://www.testgrid.io/blog/functional-vs-regression-testing-key-differences/

Everything You Need to Know About Functional Testing. (2023, January 27). Everything You Need to Know About Functional Testing. Retrieved February 6, 2023, from https://www.headspin.io/blog/a-complete-guide-to-functional-testing

https://www.appsierra.com/blog/functional-testing-vs-regression-testing. (n.d.). Retrieved February 6, 2023

Functional vs Regression Testing: What’s the difference? (n.d.). Functional Vs Regression Testing: What’s the Difference? Retrieved February 6, 2023, from https://testsigma.com/regression-testing/functional-regression-testing#:~:text=The%20purpose%20of%20functional%20testing,and%20the%20system%20works%20fine.

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