phpunit - Testing constructor with dependency injection

Question

I need to test following constructor which has dependency injection using phpunit. For that do I have to use mocking ? If so please give an example.

/**
 * Set graph object
 *
 * @param Graph $graphObj graph object
 */
public function __construct(Graph $graphObj)
{
    $this->graphObject = $graphObj;
}

Answer 1

Assuming phpunit:

$mockGraph = $this->getMockBuilder('Graph')
                  ->setMethods(array('update'))
                  ->getMock();
$testObject = new Object($mockGraph);