Mocked class not accepting instance of Carbon - unit-testing

Question

I am trying to test a method with PhpUnit and Mockery. In the process of specifying a method should be called with arguments my test fails.
TEST:
$this->eventRepo = \Mockery::mock('Path\To\EventRepository');
$start = Carbon::createFromFormat('Ymd-H-i-s', '20141211-09-21-00');
$end = Carbon::createFromFormat('Ymd-H-i-s', '20141211-09-19-00');
$this->eventRepo
->shouldReceive('findEvent')
->withArgs([
$start,
$end,
'1',
'1234567891'
])
->andReturn($callEvent);
REAL CODE:
$start = Carbon::createFromFormat('Ymd-H-i-s', '20141211-09-20-00');
$end = Carbon::createFromFormat('Ymd-H-i-s', '20141211-09-20-00');
$event = $this->eventRepo->findEvent(
$start->subSeconds(60),
$end->addSeconds(60),
$id,
$number
);
ERROR FROM TEST:
Mockery\Exception\NoMatchingExpectationException: No matching handler found for EventRepo::findEvent(object(Carbon\Carbon), object(Carbon\Carbon), "1", "1234567891"). Either the method was unexpected or its arguments matched no expected argument list for this method
$this->eventRepo is a mocked in the test. The real code runs correctly. After the error displays, it, I guess var_dump()'s a instance of Carbon.
I have no idea what could be causing this. I tried googling it but not knowing what to google made that pretty worthless. Has anyone run into this before?

Answer 1

When using an object in with() or withArgs(), phpunit performs an === check. This means that it'll look for the exact same instance of the class, not just any instance of Carbon.
In this case, it means that findEvent() is receiving an instance of Carbon, but not the exact same instance that you have in the actual code.