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Functional Testing Vs Non-Functional Testing

What is Functional Testing?

Functional Testing is the type of testing done against the business requirements of the application. it revolves around the functional aspects of the system or subsystems and how efficiently the system executes its functions. This testing is carried out by specifications provided by the client, or use cases provided by the design team.

In actual testing, testers need to verify a specific action or function of the code. For functional testing either manual testing or automation tools can be used but functionality testing would be easier using manual testing only. 

Performed either manually or with the assistance of automated tools, during the process of functional testing, testers test how well the system performs as well as its core functions, text input, installation, setup, usability, and more. Functional testing is an immensely valuable testing technique for validating that the output of the application is in compliance with the client’s requirements.

 Common Functional Testing Techniques

Installation testing: for desktop or mobile application, testing proper installation

Unit testing: testing performed at the smallest level of the software, not how the system is functioning as a whole, but whether each unit is executing properly

API testing: checks that internal and external APIs are functioning properly, including data transfer and authorization

Regression testing: tests that are performed to verify that new software changes did not have adverse effects on existing functionality (most common automation technique).

What is Non-Functional Testing?

The objective of this testing is to test the readiness of the application as per the non-functional requirement, which is overlooked during the process of functional testing. Moreover, it evaluates the competency & effectiveness of the application under various load and conditions. During this type of software testing, the prime focus of the tester’s is on validating impeccable user experience.

it is the type of testing done against the non-functional requirements. by which software engineers are able to optimize the way product is installed, setup, executed, managed, and monitored. this test helps reduce the production risk and cost, which are associated with the non-functional aspects of the product. Additionally, it plays a major role in ensuring that the quality attributes of the software product are identified correctly.

Non-Functional Testing Techniques

Load testing: tests performed on the simulated environment to test the behavior of the system during expected conditions.

Stress testing: testing performance when low on resources, such as server issues or lack of hard drive space on a device.

Scalability testing: checking a system’s ability to scale with increased usage and to what extent performance is affected.

Volume testing: testing performance with a high volume of data, not necessarily the high number of users, but could be one user performing a high-volume task, such as a multiple-file upload

Security testing: tests performed to uncover how vulnerable the system is to attacks, and how well data is protected

Disaster recovery testing: checks on how quickly a system can recover following a crash or major issue

Compliance testing: tests of the software system against any set of standards whether due to industry regulations or a company’s set of standards.

Usability testing: testing whether the GUI is consistent and if the application as a whole is intuitive and easy to use

The difference between functional and nonfunctional testing

1- Functional requirements describe the behavior or execution of the software system. but Nonfunctional requirements describe the performance or usability of the software system.

2- While a functional requirement will specify that a feature must execute some action, a nonfunctional requirement might specify the speed with which the feature performs that action.

3- Functional is What, but nonfunctional is How.

4- So, the testing of functional requirements is the verification that the software is executing actions as it should, while nonfunctional testing helps verify that customer expectations are being met.