Difference between Functional and Non Functional Testing

Before us proceeding towards the Difference between Functional and Non Functional Testing it is very important for us to first take a brief look at Functional and Non Functional Testing.

Functional and Non Functional Testing is what?

Functional testing is performed using the functional specifications provided by the client or you can say by using the design specifications like use cases provided by the design team.

In this, tester has to test the application to see that all requirements of the client which he has said in SRS and BRS have been incorporated or not.

Non Functional Testing is that which is always concerned with the client expectations like performance, load and stress issues and so on.

Distinction between Functional and Non Functional Testing

Functional Testing	Non- Functional Testing
1. In functional Testing tester tests how well the system performs.	1. In Non-Functional Testing tester tests how well the system responds.
2. Functional Testing is based on client requirements.	2. Non- Functional Testing is based on client expectations.
3. Functional Testing means Testing the application against business requirements.	3. Non- Functional Testing means Testing the application against clients and performance requirements.
4. It is a part of System Testing.	4. It is also a part of System Testing
5. Functional Testing Validating the behavior of application.	5. Non- Functional Testing Validating the performance of application.
6. This Testing covers Unit Testing, Integration Testing, Smoke Testing, Sanity Testing, Regression Testing and so on.	6. This Testing covers Load/Performance Testing, Stress/Volume Testing, Security Testing, Installation Testing and so on.
7. It is always concentrating on customer requirements.	7. It is always concentrating on customer expectations.
8. Functional Testing means how is your system is doing.	8. Non- Functional Testing means how well your system is doing example usability, performance and stress testing.