在phpUnit中模拟异常

Question

The method I am trying to test has a try catch like

try {
    $fooClass->doStuff(); // Throws \Lib\Custom\Exception
} 
catch (\Lib\Custom\Exception $exception) {
    return false;
}

I want to test if the return is false, but the custom exception is not loaded when my tests are executed.

Php unit has the option of mocking classes, but I can't seem to use this for Exceptions.

$exceptionMock= $this->getMockBuilder(\Lib\Custom\Exception::class)->getMock();

$fooClassMock = $this->getMockBuilder(fooClass::class)->getMock()
     ->method('doStuff')
     ->willThrowException($exceptionMock);

Gives me the folowing exception:

Argument 1 passed to 
PHPUnit_Framework_MockObject_Builder_InvocationMocker::willThrowException() 
must be an instance of Exception, instance of Mock_Exception_c4dd9394 given

How to properly mock this Exception to test the function?

Answer 1

The reason that your test isn't working is because the class isn't known in the test. When that happens and you create a mock in PHPUnit, it does some trickery to create a class definition and then extends that to create the mock. Otherwise it would use the extend the class itself and you would not have had a problem.

In this case, PHPUnit creates a fake \Lib\Custom\Exception and then uses that to create the mock. The fake class created doesn't extend anything (since it wouldn't know what to extend/implement). So the type hint in the willThrowException will not be matched because your mock object didn't extend Exception.

This would happen with any type hinting for extended classes in PHPUnit if the class is not loaded in the test. In order to fix this, you need to have the class available in the test via a require, include, or autoloader.