Software Functional Testing: A Comprehensive Breakdown

Timothy Joseph
Timothy Joseph | August 4, 2020

Software Functional Testing: A Comprehensive Breakdown

If you want a bug-free product, your QA team must carry out both functional and non-functional testing. QA teams tend to be more familiar with executing non-functional tests to ensures the usability and performance of the product, leading to less time and attention on functional testing where many of the defects often hide.

Functional testing doesn’t have to be intimidating. With the understanding of the value that functional testing can bring to your development cycle, your team can then plan how to incorporate functional testing services within your QA testing procedures.

But what is functional software testing? What are the tools that support functional testing? And how do you do functional testing?

This comprehensive breakdown answers all of your top questions about functional testing, from how to test software functionality to which are the best functional testing tools.

What Is Functional Software Testing?

Functional software testing is a type of software testing designed to verify software against the functional requirements and/or specifications. The goal of functional testing is carrying out tests for each function of the software product in which the tester (with the help of functional testing tools) provides the appropriate input and validates the output against the functional requirements.

What is functionality in software testing? Functionality is what a product, including software apps, can do for a user. In software testing, QA engineers execute test cases to confirm that the intended functionality of the software product meets pre-determined expectations. To do this effectively, QA teams execute functional testing for the User Interface, APIs, database, security and client/server communication as well as additional functionality of the software product under testing.

There are key differences between functional and non-functional testing in software testing. While non-functional testing focuses on the performance and usability of the software system, functional testing concentrates on the behavior and execution of the system. For example, functional testing confirms that the intended action of a specific functionality is executed, while non-functional testing validates the speed in performing this action.

How to Test Software Functionality

Now that you know what functional testing is, let’s discuss how you execute functional testing. QA teams follow these five steps when performing functional testing:

  1. Confirm the Software Engineering Requirements
  2. Identify test input (or test data)
  3. Measure the expected outcomes with the selected test input values
  4. Perform test case
  5. Compare actual results with expected result

Types of Functional Tests

A strong QA process for software products should include these types of functional tests for the most accurate results on product behavior. Here’s how to test software functionality:

  • Unit testing: Does each unit of the software code perform as expected?
  • Regression testing: Does existing functionality behave as expected alongside the addition of new code, enhancements and bug fixes?
  • Integration testing: Do the software modules behave as expected when integrated together within the software system?
  • Smoke testing: Does the software product remain stable after build deployment?
  • Sanity testing: Upon completion of smoke testing, do all major and vital functionalities of the software application behave correctly?

Functional Testing Tool Specifications

Now that you understand how to test the functionality of software, let's discuss the tools commonly used to execute the tests. After all, what is functional software testing without the assistance of a functional testing tool?

A strong testing tool is designed to streamline your functional and non-functional testing in software testing, so it’s important to have the right functional testing tool in place. Your team should consider these questions when choosing a functional testing tool:

  • Is the functional testing tool easy to use for all QA team members?
  • Can the functional testing tool operate seamlessly across various environments?
  • Does the functional testing tool provide features specific to your team’s needs?
  • Can the functional testing tool support the reusability of test cases?

Top Functional Testing Tools

Can a team do functional testing without a functional testing tool? Yes - but expect longer testing cycles, lower test accuracy and more mistakes within the testing process.

The best way on how to test software functionality is by choosing the right automated functional testing tools for your team. Make sure to consider these functional testing tools during your evaluation process:

  • Selenium: This open source functional testing tool can be downloaded and used for free across Windows, MAC OS and Linux. Selenium is an easy-to-use tool that accepts multiple languages for test scripts including C#, Java, Perl, PHP, Python, Ruby and Groovy.

  • Tricentis: Considered as one of the most effective end to end functional testing tools on the market, Tricentis uses a model-based approach best executed in an Agile method development cycle. Test cases can be created in less time and supports both manual tests and automated test scripts.

  • TestComplete: This functional testing tool is great for testing all platforms, including web, desktop and mobile applications. Users can execute test cases with different languages including JScript, VBScript, C++ and C#. TestComplete can support simultaneous testing as well as a variety of defect tracking tools such as Bugzilla, Jira and VS 2005

  • UFT: Unified Functional Testing (UFT), an automation tool introduced by Micro Focus, is best known for supporting functional and regression testing. In UFT, visual basic scripting can be used to automate test scripts as well as combine manual, automated and framework-based test scripts within one integrated development environment.

  • Watir: Web Application Testing in Ruby (Watir) is an open source functional testing tool (read: FREE) that is supported across a selection of browsers so that teams can automate web applications. Watir is designed to make reading, maintaining and understanding tests easy for all types of users of the testing tool.

What’s Next?

Having all the answers to what is functional software testing is a great start to your QA process, especially since both functional and non-functional testing in software testing are critical for software success. But answers can often lead to new, more challenging questions to tackle. For example, how do you do functional testing when you simply don’t have enough resources to carry out this kind of testing effectively and accurately?

When your team needs additional assistance with functional testing, choose to partner with a QA services provider like QASource. Our experienced QA engineers are skilled in all types of functional testing and specialize in managing functional testing tools. With our team of experts, your business can create a framework that properly supports all essential functional testing so that you’re confident in the testing results you receive from one development cycle to the next. Get in touch with a QASource expert today.


This publication is for informational purposes only, and nothing contained in it should be considered legal advice. We expressly disclaim any warranty or responsibility for damages arising out of this information and encourage you to consult with legal counsel regarding your specific needs. We do not undertake any duty to update previously posted materials.