A Quick Guide to Functional Testing

Testing is a vital part of developing software. It has multiple facets, including checking what a product does, how well it does it, all while ensuring that software operates properly for consumer use.

Part of that involves functional testing. Below, we’ll discuss what that is, it’s necessity, while comparing it to other types of testing.

We’ll also discuss important tools that may help out with the process.

Functional Testing: Definition

This is a form of software testing that checks how a product operates. Specifically, it ensures whether the software works in accordance with specific system/business requirements.

Most of the time, this form of testing doesn’t require to view the software code. This means that most functional tests are classified as “black box” testing.

Black Box Testing

It’s defined as a test that checks how the code operates, without peering into its internal structure. It looks at software from an end-user perspective. It checks different functions while mapping out a cause and effect graph.

The goal is to see if the code works in accordance with a specific outlined input/output, as defined by the software’s developers. So, is it a Quality Testing Measure? No. Think of it this way.

With functional testing, you check how a product (or app) works and how its functions are executed. However, what you do not test is how fast they’re executed or how the performance of an app changes across browsers.

As a result, this type of testing looks at the details of how an app operates.

The Focus of Functional Testing

This test looks at almost every function in software and not just focus on specific facets. It focuses on how all the functions of a program are to be used.

Functional testing looks at multiple factors, from APIs and security, to user interface, security systems, and how the application functions under testing.

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Additionally, the testing can be done manually, or in an automated manner. Though automated testing covers as many functions as possible, and with more accurate results.

Primary Goals

While functional testing looks at all uses of a system, it prioritizes the basic functions of software above others. Specifically, it concentrates on…

  • An application’s main functions
  • Basic use. This involves checking navigation, and how easily a user can change interfaces, screens, and access to different tools
  • Checking how accessible a system is to a user
  • Functional testing attempts to check the functions that display error messages. It also checks whether error messages displayed as suitable for the situation.

How Functional Testing is Performed?

In order to functionally test an application, the following steps must be observed…

  • Define input (testing data).
  • Define “output expected using the defined input.
  • Execute multiple test cases.
  • Comparing real results with the expected output.

How Functional and Non-Functional Testing Differ

To clarify what functional testing looks at, we’ll do a comparison on what each focuses on.

(A) Goal

Functional testing focuses on specifics. A client or software designer supplies certain specifications to be verified against the system. From there, the tester operates within those parameters.

With non-functional testing, general metrics such as scalability, reliability, and performance of the software are checked.

(B) Priority

Functional testing is usually performed before non-functional testing. The reason is, it’s difficult to assess the general performance of a system if the specific functions of a system aren’t working properly.

(C) Tools

Since functional testing looks at specifics, both manual and automated testing tools can work. In fact, manual testing is sometimes easier for functional testing.

But for non-functional testing, automation is faster – where manual testing is more difficult.

(D) Sources of Input

Functional testing is done to check that the software conforms to design and business specifications. Non-functional testing is performed to check general metrics, like scalability and speed.

(E) Results

Functional testing looks at what the software does. Non-functional testing focuses on the quality of the said product.

Functional Testing Tools

Functional testing can be performed manually. However, there are certain tools that may speed up the process – even assisting functional testing teams.

They include the following:

(A) Selenium

Another thing to know is the “different parts” of Selenium. This tool comes as a Web-Driver and IDE version. The Web-Driver versions let you create regression tests for browsers. It lets you create testing scripts for multiple environments.

This is a tool specifically developed for web applications. When testing an app on multiple tools, this is a prime option.

It’s written in JAVA, and it’s fairly recent, only being a year in age. The tool costs $29/month for use, which is cheap from a business perspective.

But the IDE version is more focused for bug scouting. There, you can create scripts for exploratory testing. And Finally, Selenium comes with an add-on for Chrome and Firefox. This lets you playback interactions between the executed script and browser.


It’s another tool that is recommended, it is designed by HP for functional testing. Also known as “Quick-Test,” this tool was launched in March 2018, and uses the Windows operating system.

It provides an easy to use and handle interface. It lets you select and perform different operations via mouse and keyboard.

It also provides a keyword view for creating tests and steps in a table format. A user can swap into an expert view, which lets them view and modify the source code as they test.

The only drawback of this tool is its operating system limitations. It’s primarily designed for a Windows setting. As a result, if you’re using Mac (or even Ubuntu), you may struggle a bit with this tool.

(C) SoapUI

This open-source app testing tool is the oldest thus far, launched back in 2017. It focuses on Java.

This tool supports many web protocols, such as SOAP and HTTP. This tool also comes with great variance in what it allows you to test.

Through it, you can perform load, compliance, functional, and regression testing. It works best for those seeking tools that support a large range of technologies and protocols. That is – if your business focuses on designing many types of APIs, then this tool is for you.

(D) Watir

This is an open source tool that uses the Ruby language. It’s powered by Selenium. In fact, you can use this tool in combination with Selenium.

It is known to ease the writing of Selenium scripts, which allows you to perform functional tests faster and at higher frequencies.

Also, this tool is useable on multiple browser systems. And like its Selenium variant, it comes in multiple packages,

  • Watir-Classic.
  • Watir-Webdriver.
  • Watir-Spec.

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In Summation

Functional testing attempts to ensure that a system functions “perfectly” – according to developer specifications.

It’s less focused on quality and more on whether a system works or not. As a result, it’s a vital part of testing and is a pre-requisite to quality control.

If you’re a software tester (or seeking better tools to learn), you can try the above-mentioned tools. We believe it might assist you in the programs you’d like to test.

Author: Pradeep Parthiban
Pradeep is a Content Writer and Digital Marketing Specialist at Indium Software with a demonstrated history of working in the information technology and services industry.