PHPUnit, mocked interfaces, and instanceof

Question

Sometimes in my code, I'll check to see if a particular object implements an interface:

if ($instance instanceof Interface) {};

However, creating mocks of said interface in PHPUnit, I can't seem to pass that test.

 // class name is Mock_Interface_431469d7, does not pass above check
 $instance = $this->getMock('Interface'); 

I understand that having a class named Interface is different from a class implementing Interface, but I'm not sure how to get deal with this.

Am I forced to mock a concrete class that implements Interface? Wouldn't that defeat the purpose of using an interface for portability?

Thanks

Solution 1

This works for me:

$mock = $this->getMock('TestInterface');
$this->assertTrue($mock instanceof TestInterface);

Maybe it's a typo or maybe $instance isn't what you think it is?

Solution 2

there is also assertInstanceOf as of 3.5.0

Example:

$this->assertInstanceOf('\Models\User', $this->userService->findById(1));

Solution 3

Use PhpUnit function assertInstanceOf.

Example:

$this->assertInstanceOf(ResponseInterface::class, $signInResponse);

Comments

[learner]

Yep, cooler heads prevail. After a night of full sleep, I realized I wasn't using the fully qualified namespace when mocking the object.

[stefgosselin]

This is recommended way of type checking.

[kapad]

Slightly different use case, but can I check if an instance is an instance of a class or of a mock of the class.

[Dmitry]

@kapad You see, this is the main point of Polymorphism that you don't have to know if the current object is and instance of class or a mock. If you still need to know, then you do something wrong. P.S. Just FYI you can use get_class function to know the exact class name of the object

[kapad]

@dvaffection Already solved using get_class(). I wanted to test, and definitely do something wrong. The point was to check an edge case.

[emix]

In addition to @stefgosselin answer, this is recommended way of type checking, because you get better, self explaining error messages. Compare failed asserting that object is instance of Class to fail asserting that false is true.

[Vegard Larsen]

As of PHP 5.5 you can use \Models\User::class instead of '\Models\User', which makes it a lot easier to do refactoring.