Difference Between Regression Testing And Functional Testing

The response determines your testing method (manual and automation testing) and how you set up your tests and test cases. There are many articles on the subject that compare different end to end testing approaches, but most of them don’t offer an understandable visual that can aid both parties in deciding whether to follow the management or QA path.

This article fills that need by offering two distinct charts that contrast regression testing and functional testing.

What Is Functional Testing?

Software testing is done to ensure the final product satisfies the desired requirements. During the testing phase, we validate to determine if we are building the software correctly and verify that we are building the right software.

Software testing is categorized in several ways:

1. White Box and Black Box testing are two names for it

2. It may also be referred to as Functional, Non-Functional, or Maintenance testing. There are two categories into which testing can be divided:

  • Functional
  • Non-functional

Black-box testing, an example of functional testing, means that the tester is not concerned with the underlying code. In order to ensure that the software application’s features and functions adhere to the requirements specification, this is done.

Functional testing verifies that the product developed by developers adheres to the specifications provided by stakeholders. It is about how each action module, unit, or feature should operate, not about user testing. Test cases created from positive and negative scenarios are used to carry out functional testing.

The two types of functional testing are static and dynamic. Starting with the earliest stages of product development is always preferable. It verifies:

  • Lacking capabilities
  • Incorrect specifications
  • If any interface flaws remain after the requirements phase

Functional testing done correctly results in the delivery of a premium product. It benefits:

  • To create software or a product free of bugs.
  • To verify and ensure that all requirements are created, tested, and implemented as intended.
  • Ensures security and safety.
  • To make sure the end user is happy.
  • To guarantee the proper operation of all a product’s features in an application or piece of software.
  • To guarantee the proper operation of all a product’s features in an application or piece of software.
  • As product quality improves, risks related to the hardware or software are dramatically decreased.

Let’s examine a few functional testing instances:

  • Check to see if the page’s back button takes you to the right page.
  • Check that links are leading to the pages.
  • When activated, drop-down menus should display the correct values.
  • Make sure the next button advances to the following page.
  • Check to see if a user can enter characters into the text fields in the manner specified by the data element sheet.

Regression to the Function Testing involves running the application again after new features have been added or after changes have been made to the current application. Similar features, functionalities, and flows are checked as they were during the functional testing phase. It makes sure the application functions as well as it did before. Functional regression testing is performed to determine whether application modification has not resulted in a code break. It verifies:

  • End-to-end flow functions well.
  • Received output data is accurate or not.
  • The expected data flow exists between the modules.
  • Non-functional testing involves evaluating the application’s performance, usability, security, dependability, load, stress, and other non-functional features. The primary goal of this type of testing is to see how the system will function in real-world situations.

What Is Regression Testing?

The dictionary defines regression as “the return to a former or less developed state.” Regression testing is thus defined as testing carried out intending to discover any errors in functionality that have already been tested.

The “bug fixes,” “new features added to the code,” or “changing requirements” that lead to these regressions in the code can all cause. To make sure that no new bugs are introduced into a previously tested functionality, it is important to test every piece of code that recent changes may have affected.

  • Regression testing is carried out when software has had any patches added or its configuration altered.
  • If fresh Change Requests are added, the build will be updated.
  • Any functionality or new features have been added.
  • The improvements change the functionality that already exists.
  • Regression testing may be used to: Identify bugs that recent build changes or modifications have introduced.
  • After addressing bugs or making any changes, look for any adverse effects.
  • Check for ongoing change requests because recent problems are likely, if there are any.

Functional Testing and Regression Testing: The Differences

In this topic, we’ll talk about how the two testing types differ from one another in a variety of ways.

Testing goals

Functional testing aims to evaluate how closely the developed application adheres to the required specifications. Regression testing is used to ensure that no application or system changes have resulted in code breaks and that the system continues to function as intended.

Test Case Executed

The functional testing test suite includes a brand-new set of cases and functionalities that have never been tested or used before. When a requirement-related defect is reported, the test cases are again run. It is then fixed and given a new test to pass. If the defect is fixed, the linked test cases that previously failed pass during retesting. Cases that were previously tested and passed are included in the regression suite. Regression testing basically involves running test cases again to make sure modifications haven’t affected previously tested features.

When Testing Is Necessary

Functional evaluation is necessary

  • When an experimental system is being used.
  • When the specifications and desired requirements of an application are checked.
  • To ensure proper system and module integration.
  • When it is necessary to assess the overall functionality of a system.
  • To find out a system’s workflow and functions.
  • To confirm that end-to-end flows produce the desired results.

Regression analysis is done when:

  • The client submits a change request (CR), which causes the codebase to change.
  • The backend code has been moved to a unique system.
  • The application already in use gains a new feature.
  • There are also patch fixes.
  • Changes have been made to the testing environment.
  • The developer corrects serious bugs discovered by the tester during the testing phase.
  • The developers have addressed the main issues with crashes and performance problems.

Techniques Employed

The following are the methods employed in functional testing:

  • Black Box testing
  • System integration testing
  • White Box testing
  • Interface testing
  • Unit testing
  • System testing
  • Integrating testing
  • Acceptance testing

The methods most frequently employed in regression testing are:

  • Component-based
  • Aspect 
  • Database
  • Web Apps


Functional testing is done using the following method: First, testers read and comprehend the requirements and then identify the test input after noting any discrepancies. Supplying input values to the systems and contrasting the results with what was expected. If the outcome differs, the defect is pointed out, and the test case is deemed unsuccessful. The full functional testing procedure entails the following:

  • Choosing the functionality that will be tested
  • Increased data request
  • Carrying out test cases
  • Evaluating the results against a predicted result.
  • Failure of the test case that did not adhere to the requirement
  • Designing test scenarios under the requirement
  • Making test cases from test scenarios
  • If any inconsistencies are discovered in the application, reporting bugs and giving the developer the assignment
  • Retrying the failed case after the issue is resolved

Regression testing, however, is a completely original process because it is only performed when an existing application is changed or new features are added to it.

The following are the tasks involved in this kind of testing:

  • Identifying changed components
  • Test case prioritization based on level of risk.
  • Selection of test cases based on the changed areas’ impact.

Automating Potential

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

Check here to see if your team needs to adopt automation.

Maintenance and modification of the test script: Because functional test cases are fewer and feature-specific, they don’t require as much modification.

As the regression test suite is built to test overall functionality, test scripts there require more maintenance. Test cases could include features that have been removed, new features that have been added, or functionalities that have changed. In order to prevent the failure of automation scripts, the regression suite should be updated following each release.

Functional Testing & Regression Testing: The Methodologies

You can now easily comprehend how the two approaches/methodologies differ from one another:

Regression Testing

  • It is a procedure for verifying software improvements and modifications.
  • Rerunning previously run tests on a new build or builds and comparing the results with earlier builds are involved.
  • The aim is to confirm that, following the introduction of changes to the application, older functionalities continue to function as expected.
  • It aids in ensuring that changes are implemented properly and the application is still functioning as expected.
  • It offers useful details about code changes but little about the application’s operational/business behavior.
  • Furthermore, it is expensive because all previous test cases must be run again on more recent builds.
  • While some of it can be automated, the majority of it must be done manually.
  • It is a retrograde strategy.

Functional Testing

  • Functionality is verified automatically using a variety of user inputs.
  • On one or more data sets, it entails running each test case that has been specified for the entire product or feature being tested.
  • Verifying that functionalities work as intended is the goal.
  • It aids in verifying that an application is carrying out tasks as described in the documentation for a specific feature.
  • With no human intervention, automating and running tests is simpler (for scenarios without a user interface).
  • The aim is to confirm which button(s) was/were pressed, when, and why.
  • This technique aids in confirming that changes made to the application behave as expected.
  • It offers useful details about the application’s commercial behavior.
  • It is the best strategy for both functional test automation and regression testing.

Functional Regression Testing Instruments

A few of the best tools for automating the regression suite are covered in the section below. Each has distinctive qualities of its own that make the automation process simple and understandable for those who are unfamiliar with it.


A Ruby acronym for web application testing. It is a free and open-source Ruby library for web browser testing. It requires a solid command of the straightforward, understandable Ruby language. Native application automation is not possible with it.

Key attributes or services offered: All browsers are supported, and web elements are simple to interact with.


A time shift regression testing service is TimeShiftX. It creates a virtual clock container that enables applications to move forward or backward in time to assist with short-term or date-simulating testing.

Key attributes or services offered:  requires no reloading or environment reboots, supports all platforms and operating systems, requires no changes to the code, compatible with database and application.


It is a free software program. For testing on mobile devices, a wrapper for Selenium is used. Either real devices or emulators can run the automation test script.

Key attributes or services offered:  Executing tests in parallel is supported, which speeds up testing and improves its effectiveness. All operating systems are also supported.


Smart Bear created the automated regression testing tool known as TestComplete. Functional test scenarios and backend scenarios, like database testing, are made easier to automate by this. It works with all operating systems, browsers, and native applications. You must have a foundational understanding of coding to use the automation tool.

Key attributes or services offered:  Supports object-driven testing, data-driven testing, keyword-driven testing, integration with other tools, creation of unique extensions, and compatibility with all web browsers and operating systems.


It is a free tool for automating web testing. To create a powerful automation framework, it supports many third-party libraries.

Key attributes or services offered: Supports parallel test execution, which speeds up and improves the effectiveness of tests. It can be integrated with source code compilation frameworks like Ant and Maven.


It is a model-based test automation tool with integrated business intelligence that is widely used across all platforms. With only a few manual steps, this tool automatically scans the AUT(Application Under Test) script and loads it into the software. The tool uses business intelligence to suggest some important tests that aid the team in identifying problem areas.

Key attributes or services offered: All platforms and browsers are supported, interactive testing is supported, and built-in artificial intelligence is.

Cloud-based testing platforms like LambdaTest offers online Selenium Grid infrastructure allows you to perform automation testing on 3000+ real browsers and operating systems. The major advantage of using a reliable online Grid infrastructure like LambdaTest is that it doesn’t require additional software (or plugin) installations on your machine. The browsers on VMs in LambdaTest have pre-installed versions of Adobe Flash, Adobe Shockwave, Microsoft Silverlight, etc., making it easy to test rich internet apps.

The Bottom Line

Regression testing is strongly advised whenever an existing product is changed, or a new feature is added. But it becomes challenging to choose between running the regression suite, which tests functionalities essential to happy flows, and another full cycle of functional testing.

Every regression case in an organization is designed with a tag attached to it based on the priority of the case, such as Tier 1 (all happy flows), Tier 2 (Major functionality), or Tier 3. (Minor functionality). Tier 1 is the highest, and tier 3 is the lowest.

The best way to decide is to research the risk at stake, the module that will be affected, and the testing window after the change has been incorporated into the project. Which functionality underwent a change and how crucial it was for the application will always determine the level of risk involved.

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