What Is Functional Testing?

Software testing is carried out to ensure the final delivered product meets the desired requirements. Validation to understand if we are building the software right and verification if we are building the right software are both done during the testing phase.

Classification of software testing is done in various ways:

1. Some call it as White Box and Black Box testing

2. Others may call it Functional, Non-Functional, Maintenance testing. Broadly all testing types can be categorized into 2 types of testing:

  • Functional
  • Non-functional

Functional testing is a type of black-box testing, which means the tester is not concerned with the underlying code. It is done to verify that each function/feature of the software application functions in conformance with the requirements specification.

Functional testing checks and assures that the product designed by developers works as per requirement specified by stakeholders. It is not about user testing, it is about how each action module/ unit or feature should work. Functional testing is carried out with the help of test cases that are derived out of all possible scenarios, both negative and positive.

Functional testing is both static and dynamic. It's always better if it starts at an initial level of product development. It checks:

  • missing functionalities
  • incorrect specification
  • if any interface errors persist
  • gap that exists during the requirements phase

A well derived functional testing leads to delivering a high-end product. It helps:

  • to produce a bug-free product/software.
  • to check and assure that all the requirements are developed and tested as desired.
  • assures safety and security.
  • to ensure the end-user satisfaction.
  • to ensure the proper working of all the functionalities of an application/software/product.
  • to ensure the proper working of all the functionalities of an application/software/product.
  • Improve the quality of the product and risks associated with the product/software are exponentially reduced.

Let’s look at a few examples of functional testing:

  • Verify that the back button on the page is navigating to the correct page
  • Verify that links are redirecting to the right pages.
  • Drop-down features should list correct values on click
  • Verify that the next button takes to the next page
  • Verify that a user is able to type characters into the text fields as defined in the data element sheet

Functional Regression Testing is to test the application once more after new features are added or modification is done in the existing application. It checks for the same features, flows, functionalities as it was done during the functional testing phase. It ensures that the application runs smooth as it was working earlier. The purpose of the testing while performing functional regression testing is to check if modification of the application has not led to code break. It checks for:

  • End to end flow works fine.
  • Output data received is correct or not.
  • Data flow between modules is as expected.

Non-functional testing is to test the application from non-functional aspects such as performance, usability, security, reliability, load, stress, etc. It is basically done on live scenarios usually to check how the system will perform when kept under such circumstances.

Read more details about types of functional testing.


What is Regression Testing?

Dictionary meaning of the word "regression" is "the return to a former or less developed state." So, testing done with the aim of catching any regressions in an already tested functionality is called Regression Testing.

These regressions in the code can occur as a result of “bug fixes”, “new features added to the code” or “changing requirements”. The aim is to test all the code that could be impacted due to recent changes to ensure that no new bugs are introduced in an already tested functionality.


Difference Between Functional Testing and Regression testing

In this topic, we would be discussing the difference between both testing types with respect to various aspects.

  1. The purpose of testing:

    The purpose of functional testing is to determine how closely the developed application matches the desired requirements. Whereas, the purpose of regression testing is to check that any change in the application or systems have not led to code break and the system works fine.

  2. Test case executed:

    The test suite of the functional testing comprises a fresh set of cases and functionalities, which were never tested and executed before. The test cases are re-executed when the defect is raised against a requirement. Subsequently, it gets fixed and assigned for re-test. During retesting if the defect is closed, the linked test cases which failed earlier are passed. The regression suite contains cases that were previously tested and passed. Basically, in regression testing, test cases are re-executed to ensure changes have not impacted previously tested features

  3. When is testing required:

    Functional testing is required:

    • when a new system is being tested.
    • when an application is verified against its specifications and desired requirements.
    • to check system and module integration works fine.
    • when the functionality of a system as a whole has to be examined.
    • to determine the workflow of a system and its functions.
    • to ensure that end to end flows yield expected output.

    Whereas, regression testing is done when:

    • a change request(CR) is raised by the client, which leads to change in the codebase.
    • backend code is migrated to a different platform.
    • a new feature is added to the existing application.
    • patch fixes are added.
    • there is a change in the testing environment.
    • critical bugs found by the tester during the testing phase are fixed by the developer.
    • the major concerns about performance issues and crashes are fixed by the developers.
    • the UI of the application is changed for better user experience.
  4. Techniques used:

    The techniques used in Functional testing are as follows:

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

    In Regression testing, the most common techniques used are:

    • Component-based
    • Aspect
    • Database
    • Web applications
  5. Process used:

    The process of functional testing starts with testers reading and understanding the requirements, raising a gap if any discrepancy exists in the requirement, followed by the identification of test input. Passing input values to the systems and comparing the output with the expected results. If the result does not match, the defect is raised against it and the test case is marked as failed. The entire functional testing process includes :

    • Identifying functionality to be tested
    • Raising data request
    • Running test cases
    • Comparing the output with an expected outcome.
    • Failing the test case which did not match the requirement.
    • Creating test scenarios based on the requirement
    • Converting test scenarios to test case
    • Raising defects and assigning it to the developer, if any discrepancies are found in the application
    • Re-executing the failed case once defect raised is fixed

    On the contrary, the process of Regression testing type is entirely different as this activity takes place only when the existing application is modified or new features are added to it.
    The activities involved in this type of testing are as follows:

    • Identification of modified parts
    • Prioritization of test cases based on the risk involved.
    • Selection of test cases based on the areas impacted due to modification.
  6. Automation Feasibility:

    Functional testing first is done manually and once a feature is stable, test cases are automated. While in regression testing, only those test cases are executed manually or automatically - that are already stable, so this can be automated when needed.
    To know if your team needs to adopt automation check here.

  7. Maintenance/modification of test script:

    Functional test cases don't need a lot of modification because they are less in number and focused on a feature.

    Whereas in the regression suite, Test scripts require higher maintenance, as the test suite is composed to test overall functionality. There may be chances that it can contain old test cases. Test cases may contain functionalities that have changed, new features that have been added or some features which have been removed. The regression suite should be updated after each release to avoid the failure of automation scripts.

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Tools To Perform Functional Regression Testing

Below discussed are a few tools that provide the best services in regards to the automation of the regression suite. Each has its own unique features that help make the automation process smooth and easy to understand for people who are new to the world of automation.

  1. Testsigma: one of the finest tools available in the market that provides cloud-based test automation service. It allows users to write test scripts in plain English language which is as easy as writing manual test cases. It has inbuilt artificial intelligence which helps you suggest critical areas of the applications.

    Key features/services provided: Supports all platforms(Web, Native & Desktop) and browsers. Tool provides service options to prioritize test cases, build multiple test suites, schedule and run automated regression tests for each build automatically, and generate comprehensive reports with the drill-down approach. The best part of this tool is that Coding skills are not required.

    For an in-depth study about automated regression testing and its aspects, check out our automated regression testing guide.

  2. Watir: Stands for web application testing in Ruby. It is an open-source Ruby library to automate tests for web browsers. It requires you to be well versed with the Ruby language, which is simple and easy to understand. It cannot be used to automate native applications.

    Key features/services provided: Easy to interact with web elements, supports all browsers.
  3. TestingWhiz: is a codeless automation testing tool, helps automation across all platforms. It executes and manages test cases effortlessly & efficiently. It permits users to verify the critical functionalities of their web applications and deliver efficient and effective web interfaces.

    Key features/services provided: Multiple Browser Support, Image comparison, Mobile testing support, Integration with a bug tracking tool, Integration with Test Management Tools, Captcha automation, Risk-based Testing.
  4. TimeShiftX: is a time shift regression testing service. It creates a virtual clock container that permits applications to travel in the past or future to help you perform temporary or date simulating testing.

    Key features/services provided: Requires no environment reboots and reloads, Supports all platforms & operating systems, no Code modifications required, Compatible with application & database.
  5. Appium: It is an open-source tool. It is a wrapper for selenium used for mobile testing. The automation test script can be run on physical devices or emulators.

    Key features/services provided: Supports parallel test execution which helps reduce time and increases the efficiency of tests, supports all operating systems.
  6. Katalon Studio: It is a free automation service provider tool. It has a dual interchangeable interface for creating test cases, a manual view for the less technical users and a script view for experienced testers. This tool requires basic knowledge of scripting.

    Key features/services provided: Supports all platforms(Web, Native & Desktop) and browsers, script execution on multiple devices. It can be integrated with Git, Jenkins, qTest, and Jira.
  7. TestComplete: It is an automated regression testing tool designed by Smart bear. It helps automate functional test scenarios and backend scenarios such as database testing. It can be used across all browsers, operating systems, and native applications. The automation tool demands you to have basic knowledge of coding.

    Key features/services provided: Supports Database testing, Integrates with other tools, Object-driven testing, Data-driven testing, Keyword-driven testing, Development of custom extensions, supports all web browsers, Operating systems.
  8. IBM Rational Functional Tester: Automation tool designed by IBM. This software provides services to automate functional, regression, GUI and data-driven testing

    Key features/services provided: Supports visual editing, Test scripting, Earlier data detection, Integration with other software, Story testing, Data-driven testing
  9. Selenium: It is an open-source web testing automation tool. It supports many third party libraries to build a robust automation framework.

    Key features/services provided: Supports parallel test execution which helps reduce time and increases the efficiency of tests, can be integrated with frameworks like Ant and Maven for source code compilation.
  10. Tosca: It is a model-based test automation tool, used widely across all platforms, and has embedded business intelligence. This tool automatically scans the AUT(Application Under Test) script and loads into the software with minimal manual steps. Business intelligence helps the tool in suggesting certain critical tests that help the team identify the trouble areas, and thus reducing the risk.

    Key features/services provided: built-in artificial intelligence, supports interactive testing, supports all platforms and browsers.

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FAQs on Functional Testing

Regression can be functional as well as nonfunctional. Functional Regression testing checks for change or modification in code, backend or environment changes have not led to any failures in the functionality of an application. Whereas, Non-functional regression testing checks for any performance issue which may have resulted due to new introduced changes or modification in the application.

When there is a modification or addition of feature(s) to any existing product, Regression testing is highly recommended. But it really becomes difficult to decide whether to run a full cycle of functional testing all over again or to run the regression suite which covers functionalities that are vital and happy flows.

Usually in an organization the regression suite is designed in such a way that each case of the suite has a tag associated with it depending upon the priority of the case such as Tier 1( all happy flows) , Tier 2(Major functionality), Tier 3(Minor functionality). Tier 1 being the highest and 3 being the lowest.

The best way to decide is to study the risk involved, impacted module and time allocated for testing after the change has been incorporated in the project. Risk involved will always depend on which functionality underwent change and how critical it was for the application.

Let's discuss multiple scenario to have a better idea to how to decide on:

Scenario 1: When risk level is high and time permits Which means a critical Functionality/ies underwent the change. In this case, You should run the entire functional test cases all over again to ensure new code has not impacted previously developed and tested functionality in any way.

Scenario 2: When risk level is high and time is less In such cases you cannot run the entire functional test cases all over again due to time constraints. Just Run a regression suite plus the full functional cycle of the functionality and its associated features which underwent change.

Scenario 3: When risk level is medium and Time is sufficient Since you have sufficient time it is always good to be double sure about the application before deploying it to the production. Run the entire functional test suite to have full confidence over application.

Scenario 4: When risk level is medium and Time is insufficient Since you do not have sufficient time but you need to be sure about the application before deploying it to the production. Run the entire Regression test suite as well as run more functional test cases that focus more on the functionality which underwent change.

Scenario 5: When risk level is low In such case it means that not a major functionality has undergone change. Just run the regression suite and you are good to go.

Scenario 6: Urgent change, immediate deployment and Insufficient time IIn such cases, you cannot run the entire regression suite due to time constraints,just run tier 1 cases of the regression suite which consists of all happy flows. This will help you ensure that there is no breakage in the system and end to end flows fine. Any minor defect or issue detected in such cases can be addressed later.

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