Functional testing should not be confused with Functional testing (manufacturing).
In software development, functional testing is a form of software system testing that verifies whether software matches its design.
Generally, functional testing is black-box meaning the internal program structure is ignored (unlike for white-box testing).[1]
Functional testing can evaluate compliance to functional requirements.[2]
Sometimes, functional testing is a quality assurance (QA) process.[3]
Functional testing differs from acceptance testing. Functional testing verifies a program by checking it against design document(s) or specification(s), while acceptance testing validates a program by checking it against the published user or system requirements.[4]
As a form of system testing, functional testing tests slices of functionality of the whole system. Despite similar naming, functional testing is not testing the code of a single function.
The concept of incorporating testing earlier in the delivery cycle is not restricted to functional testing.[5]
Functional testing includes but is not limited to:
Functional testing typically involves six steps