Serialization of mock issues

[garethellis36]

I came across a bit of an edge-case in a test which touched the database. I was using a Phake mock as follows:

$mock = Phake::mock(MyClass::class);
Phake::when($mock)->myMethod->thenThrow(new MyException);

The issue was that later in the test, I was passing the mock as a constructor argument to the Class Under Test and then trying to serialize the CUT. I was getting the error:
You cannot serialize or unserialize PDO instances

The thing is that MyClass did not have anything to do with the database, and neither did the CUT or any of its dependencies.

After a lot of debugging I found that the mock object had the instance of the exception stored as a data property a long way down the nested structure, and the exception itself had a trace property which included all of the global context from the test class, including the CakePHP fixture manager, which of course had a PDO instance inside it!

So this was really unexpected behaviour and after losing a few hours, in the end I could not use Phake to mock this class because of it.

I'm not sure if there is a solution to this. Perhaps Phake mocks could implement __sleep() in such a way as to exclude expected exceptions?