The AND is important!
Disclaimer: In my career I have done most of the things I describe below, but never tied them all into one project. The following should be possible:
Testing a SystemSuppose we have a software system of reasonable complexity. Suppose our system is comprised of a front end with a user interface (UI) and a back end, thus a client and a server. The front end and the back end communicate via an application programming interface (API) of some sort. This is a common architecture of many software systems.