Functional and Non Functional Testing – The Differences!

Functional and Non-Functional Testing - The Differences!

We have often read about Functional Testing and Non-Functional Testing as individual testing but let us go through the differences between these two testings in this blog.

Functional Testing – Defined & Detailed

Functional testing is a software testing process used within software development wherein the software is tested to make sure that it complies with all the requirements. Functional testing is a way of verifying a software to ensure that it has all the desired functionality specific to its functional requirements.

Functional testing is always done against the app’s business requirement that means it is a black box testing type. It involves the complete integration system to evaluate the system’s compliance with its specified requirements. This type of testing is carried out based on the product’s functional specification document. Typically, functional testing involves evaluating and comparing each software function with the business requirements. Functional testing is concerned only with the functional requirements of a system or subsystem. These include any user commands, data manipulation, searches, business processes, user screens, and integrations. This testing is done using the functional specifications provided by the client or by using the design specifications like use cases provided by the design team. So, this type of testing is strictly specific.

For functional testing either manual testing or automation tools can be used but functionality testing would be easier using manual testing only. Functional testing also checks the software for usability, such as by ensuring that the navigational functions are working as required.

Functional testing techniques include:

Non-Functional Testing – Defined & Detailed

The Non-functional type of testing is performed based on the product’s non-functional requirements. This testing tests the characteristics of the software for example, like say the speed of the response, or the time taken for the software to perform any operation. Non-Functioning testing is done based on the requirements and test scenarios defined by the client.

Non-functional testing can as well be described as testing software attributes not related to specific actions and user actions such as scalability, security, performance or app’s behavior under certain constraints. It has a great influence on customer and user satisfaction with the product. This testing is concerned with the non-functional requirements and is designed specifically to evaluate the readiness of a system according to the various criteria which are not covered by functional testing. Essentially non-functional testing lets us measure and compare the results of testing the non-functional attributes of software systems.

So, it is derived that, non-functional testing indicates the behaviour of the product and not the description of what the product does. Certainly, while functionality is important, it should not be forgotten that users’ inclination and trust of a software or system is converted and affected by non-functional qualities, so always remember that non-functional testing is crucial in its own way. Also Non-functional testing should be expressed in a testable way not in a manner which is not testable. Unlike Functional testing, to make the non-functional testing effective, it is important to use testing tools rather than testing it manually.

Non-functional testing involves following sub-types of testings:

Note: Prior to Non-Functional testing the Functional testing would be executed first.


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