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). Functional testing can evaluate compliance to functional requirements. Sometimes, functional testing is a quality assurance (QA) process. 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. 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. In fixture testing, while ICT fixtures test each individual component on a PCB, functional test fixtures assess the entire board's functionality by applying power and verifying that the system operates correctly. Types Functional testing includes but is not limited to:

Six steps

Functional testing typically involves six steps