A few days ago I was explaining mocking to a few colleagues. I came up with the following quick n dirty code to show them the elegance of Mockery as a mocking framework. The code is straight-forward: it checks the health of a server using a tiny heart beat script.
He provides both sides of the code - a simple "heartbeat" script that just responds with a JSON result, the class to consume it, a HTTP wrapper class that will be the target of the mock and his PHPUnit tests (testSystemIsOnlineWhenServiceRuns). You can see the use of the Mockery tool in this test.