What Is Functional Testing: The Ultimate Guide

What Is Functional Testing

Before a platform goes into the market, it should go through various assessments to ensure that it works. One of these is functional testing.

This blog post will guide you through functional testing, what it is, and how to do it.

What Is Functional Testing?

Functional testing assesses software’s functionality. It can include checking for correctness, accuracy, and completeness. Usually, manual testers perform this including a functional testing company. However, the process can also be automated with tools that simulate user actions and check the achievement of expected results.

Functional testing can have many benefits, including:

  • Improved software quality. By finding and fixing defects early in the development cycle, functional testing can help to improve the overall quality of the software.
  • Reduced development costs. By finding and fixing defects early, functional testing can save money by preventing them from becoming more expensive to fix later on.
  • Faster time to market. By starting functional testing early, you can speed up the development process and get the software to market faster.
  • Improved customer satisfaction. By ensuring that the software works correctly, you can improve customer satisfaction and reduce support costs.

Functional Testing Types

Many different types of functional testing are possible, each of which focuses on a different aspect of the software:

  • Usability testing. This type of testing assesses the ease with which users can use the software. Ensuring this helps improve user satisfaction and decreases support calls.
  • Compatibility testing. It sees to it that the software works correctly on different platforms and with different configurations. For example, if the platform is designed to run on Windows, it should also be tested on Linux and Mac OS to ensure compatibility.
  • Security testing. This type of functional testing assesses the security of the software. This can include assessing for vulnerabilities, such as SQL injection attacks, and ensuring that data is encrypted when it is transmitted.
  • Performance testing. It evaluates the speed and scalability of the software. The objective is to guarantee that the software can handle large amounts of data and traffic without slowing down.

What Is Functional Testing

How to Perform Functional Testing

Functional testing goes through many phases:

  • Before starting functional testing, the development team should come up with a plan. This includes deciding what to test and how to go about it. In addition, the team should determine the criteria for a successful test.
  • In this phase, the development team sets up the test environment and prepares the test data. This can involve creating test user accounts, populating databases with sample data, and configuring the software to run in a test mode.
  • Execution of test cases. The next step is to execute the test cases and check the actual outputs against the expected ones. If there are any discrepancies, then a defect has been found.
  • Reporting of defects. Once all the test cases have been executed, any defects that were found should be reported to the development team.
  • In this stage, the development team fixes the defects and the testers retest the software to ensure that the issues have been resolved.

Who Should Do Functional Testing?

Functional testing should be done by a dedicated team of testers. This team should have a good understanding of the software’s functionality and how it is supposed to work. They should also be familiar with the test environment and the tools that will be used for testing.

In some cases, the development team may perform functional testing themselves. However, it is generally best to leave this to a separate team so that they can provide an independent assessment of the software’s quality.

When Is the Best Time to Perform Functional Testing?

Ideally, functional testing should be done after the software has been through unit testing and integration testing. This ensures that all the individual components of the software are working correctly before they are put together.

However, in practice, it is often not possible to wait until the end of the development cycle to start functional testing. In these cases, it is best to start as early as possible. This allows any defects that are found to be fixed quickly before they have a chance to impact other parts of the software.

Functional testing should be an ongoing process throughout the development cycle. As new features are added to the software, they should be tested to ensure that they work as expected.

Tools for Functional Testing

There are many different tools that can be used for functional testing. These tools can be divided into two main categories:

  • Automation tools. These tools automatically execute test cases and compare the actual outputs with the expected ones. If there are any discrepancies, then a defect is logged. Automation tools can be expensive, but they can save a lot of time in the long run.
  • Manual testing tools. These are simply tools that help testers to execute test cases manually. They do not automate the process, but they can make it easier and faster. Manual testing tools include test management software and case management software.

Which type of tool you use will depend on your budget, your needs, and your preferences.


Functional testing is important to do. It can help to ensure that the software works as it should and that any defects are found and fixed quickly.

But it can be hard. If you can’t do it all by yourself, you can work with a software testing team to help you out.

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About the author



Tom is a gizmo-savvy guy, who has a tendency to get pulled into the nitty gritty details of technology. He attended UT Austin, where he studied Information Science. He’s married and has three kids, one dog and 2 cats. With a large family, he still finds time to share tips and tricks on phones, tablets, wearables and more. You won’t see Tom anywhere without his ANC headphones and the latest smartphone. Oh, and he happens to be an Android guy, who also has a deep appreciation for iOS.