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

user_9987540 · Answer

Use PhpUnit function assertInstanceOf.

Example:

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