What is Functional Testing?

Michael Harvey
August 5, 2022
 Mins Read

A software testing method wherein the system is tested to ensure that it meets the functional requirements and expected specifications mentioned in the document is known as Functional Testing. To elaborate, in functional testing, the functions or features of the software are verified by feeding the input and analyzing the output to ensure that the software meets the expectations. The focus of this type of software testing method is the result of the processing and not how the processing occurs.          

The Need for Functional Testing

Delivering high-performance and bug-free applications/systems/software has become a criticality due to the intensified competition level in the Information Technology (IT) development arena. In such a scenario, functional testing enables stakeholders and software development services to deliver a product with fewer or no issues. This process of software testing simulates the actual system usage without making any system structure assumption, thereby, helping one achieve the desired output.

The Process of Functional Testing

The black box testing technique is the most reliable one for functional testing. In this, the tester does not have knowledge about the system’s internal logic. This type of testing is performed at the system and acceptance testing levels and the steps include:

  • Identifying Functions: In this step, the tester identifies the functions that the software is expected to meet.
  • Creating Input Data: This step marks the creation of input data based on the specified functions in the development documentation.
  • Determining the Output: This step involves determining the output which is mentioned in the documentation.
  • Designing the Test Cases: Multiple test cases are designed in this step to check the performance of the software in different conditions.
  • Executing the Test Cases: Each test case is implemented thoroughly and the results are scrutinized minutely by the tester.
  • Comparing the Actual and Expected Outputs: Lastly, the tester draws out a comparison between the actual output that the software is providing after implementing the different test cases and the output that it is expected to provide.

Automating the process of software functional testing is extremely important for immediate implementation.  On the other hand, one should also note that automating the process does not guarantee the software’s functionality.  Hence, a practice that can utilize the capabilities of the functional testing process to its hilt should be devised.

Advantages of the Functional Testing Method

The prime importance of the functional testing method is to test a system’s functionality. When the programmers add a new code to any software, its new and old functionality will have to be tested to ensure that the software is performing smoothly after the said modifications are done to the code.

The test cases developed during the software’s functional testing will have to include the database of codes, the application components, and the network. This process of software testing also verifies everything that is within the software and also whether the code and the design structure are working together smoothly or not.

Other advantages of the functional testing method are that it helps in simulating the actual system’s usage, and in this process, no system structure assumptions are made.

Also Read: What is Black Box Testing and its Advantages and Disadvantages


In conclusion, the method of functional testing has proven to be more effective when the test cases are created directly as per the users’ requirements, rather than from the system documentation’s point-of-view.

Article by
Michael Harvey

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