Use the $this->fail() method with Mockery::on()

When you have a more complex assertion you need to make on the parameters of a mocked object, you might use the Mockery::on() method. It can be hard to tell how this fails, though, because if the assertion fails somewhere, the message is confusing - it basically says that there was no matching call to that method, which is technically correct.

Let’s take a look at this example:

$mockedClass->shouldReceive('process')->once()
  ->with(\Mockery::on(function($parameter) {
    $valid = false;
    if (
      ($parameter instanceof SomeClass)
      &&
      ($parameter->getProperty() == 12)
    ) {
      $valid = true;
    }
    return $valid;
  })->andReturn(true);

Here, we have a mocked class that should receive a call to the process method once and that should return true. We want to make sure that the parameter passed into the function is an instance of SomeClass and that the getProperty() method returns 12 - for some reason. This is just a contrived example of course.

Now, if everything is valid, we return true - and the test passes. However, if the parameter isn’t an instance of SomeClass - or - if the value is not right, $valid will be false. This will make Mockery give us the weird error like:

Mockery\Exception\NoMatchingExpectationException: 
No matching handler found for Mockery_2_Mocked_Class_name::process(...

This obviously is not clear - which thing failed? Or even worse, imagine if there were a bunch of checks to do - instead of just 2. How would you ever track this down?

Got the solution from a tip from my coworker Fred - it has to do with using $this->fail() in PHPUnit (or the equivalent method in your test framework of choice). Let’s check out our new test with more verbose items.

$mockedClass->shouldReceive('process')->once()
  ->with(\Mockery::on(function($parameter) {
    if (! $parameter instanceof SomeClass) {
      $this->fail('Parameter not instance of SomeClass');
    }
    if ($parameter->getProperty() != 12) {
      $this->fail('Property is not 12.');
    }
    return true;
  })->andReturn(true);

Now, when we run the script and we have an issue, it’ll fail with a more verbose message:

There was 1 failure:

1) Tests\MockedClassTest::test
Property is not 12.

This is pretty easy to tell what the exact error was - and why it failed.

As a bonus, you might also use the parameter hinting of the closure passed to Mockery::on() to get cut down on the testing you have to write. Instead of checking for instances, just require the incoming item to be that instance.

$mockedClass->shouldReceive('process')->once()
  ->with(\Mockery::on(function(SomeClass $parameter) {
    if ($parameter->getProperty() != 12) {
      $this->fail('Property is not 12.');
    }
    return true;
    }
    return $valid;
  })->andReturn(true);

If the wrong class comes in, the error will be very clear and verbose:

There was 1 error:

1) Tests\MockedClassTest::test
TypeError: Argument 1 passed to Tests\MockedClassTest::Tests\{closure}() 
must be an instance of SomeClass, instance of WrongClass given, called in
/project/path/vendor/mockery/mockery/library/Mockery/Matcher/Closure.php on line 35

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