Alternatives When Testing Asynchronous Messaging?

Hi,

 

Ok - when testing an API that utilises a nonblocking comms pattern (asynch messaging) - you don't get responses to assert against.

 

Before now - I've always had the developers create an additional 'test API' that hooks into API (that doesn't return a response) so I get a response back to assert against.

 

However - I've been looking through some old posts and the testing of Asynch message exchange patterns people use MockServices/VIRTs and I don't understand how this works.

 

Can anyone elaborate on this or explain how they test against APIs that use asynch comms?

 

Cheers!

 

rich