PHPUnit: How to mock a function on a class?

Question

I have a class called \"QueryService\". On this class, there is a function called \"GetErrorCode\". Also on this class is a function called \"DoQuery\". So you can safely sa

Answer 1

To test this class, you would mock the IntegratedService. Then, the IntegratedService::getResult() can be set to return what ever you like in a mock.

Then testing becomes easier. You also need to be able to use Dependency Injection to pass the mocked service instead of the real one.

Class:

class QueryService {
    private $svc;

    // Constructor Injection, pass the IntegratedService object here
    public function __construct($Service = NULL)
    {
        if(! is_null($Service) )
        {
            if($Service instanceof IntegratedService)
            {
                $this->SetIntegratedService($Service);
            }
        }
    }

    function SetIntegratedService(IntegratedService $Service)
    {
        $this->svc = $Service
    }

    function DoQuery($request) {
        $svc    = $this->svc;
        $result = $svc->getResult($request);
        if ($result->success == false)
            $result->error = $this->GetErrorCode($result->errorCode);
    }

    function GetErrorCode($errorCode) {
         // do stuff
    }
}

Test:

class QueryServiceTest extends PHPUnit_Framework_TestCase
{
    // Simple test for GetErrorCode to work Properly
    public function testGetErrorCode()
    {
        $TestClass = new QueryService();
        $this->assertEquals('One', $TestClass->GetErrorCode(1));
        $this->assertEquals('Two', $TestClass->GetErrorCode(2));
    }

    // Could also use dataProvider to send different returnValues, and then check with Asserts.
    public function testDoQuery()
    {
        // Create a mock for the IntegratedService class,
        // only mock the getResult() method.
        $MockService = $this->getMock('IntegratedService', array('getResult'));

        // Set up the expectation for the getResult() method 
        $MockService->expects($this->any())
                    ->method('getResult')
                    ->will($this->returnValue(1));

        // Create Test Object - Pass our Mock as the service
        $TestClass = new QueryService($MockService);
        // Or
        // $TestClass = new QueryService();
        // $TestClass->SetIntegratedServices($MockService);

        // Test DoQuery
        $QueryString = 'Some String since we did not specify it to the Mock';  // Could be checked with the Mock functions
        $this->assertEquals('One', $TestClass->DoQuery($QueryString));
    }
}