In manufacturing, functional testing (FCT) is performed during the last phase of the production line.
[1] This is often referred to as a final quality control test, which is done to ensure that specifications are carried out by FCTs.
The process of FCTs is entailed by the emulation or simulation of the environment in which a product is expected to operate.
In order for this to be completed, the software will communicate with any external programmable instruments such as I/O boards, digital multimeters, and communication ports.
In conjunction with the test fixture, the software that interfaces with the DUT is what makes it possible for a FCT to be performed.