"we sent to candidates a functional test suíte, a binary that when started would try to connect to the candidate’s server implementation, open lots of sockets,

"we sent to candidates a functional test suíte, a binary that when started would try to connect to the candidate’s server implementation, open lots of sockets, sends lots of messages, and verify the results against what the problem description stated" Codility.com is a software as service company that automates this.