Question

I am trying to test a class that extends Symfony\Component\Form\AbstractType, and having trouble testing the required buildForm method with a PHPUnit mock object:

class PageType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder->add('name', 'text');
    }

    // ...
 }

Here’s some example test code:

public function testBuildForm()
{
    $form = new PageType($this->manager);
    $formBuilder = $this->getMock('Symfony\Component\Form\FormBuilderInterface');
    $form->buildForm($formBuilder, array());
}

Unfortunately the call to getMock() fails:

PHP Fatal error:  Class Mock_FormBuilderInterface_f36f83d4 must implement interface Traversable as part of either Iterator or IteratorAggregate in Unknown on line 0

I suspect I might have fallen foul of this bug:
https://github.com/sebastianbergmann/phpunit/issues/604

So, I have created an interface to work around the problem:

use Symfony\Component\Form\FormBuilderInterface;

interface FormBuilderInterfaceExtender extends \Iterator, FormBuilderInterface
{
}

and changed my test code:

public function testBuildForm()
{
    $form = new PageType($this->manager);
    $formBuilder = $this->getMock('Pwn\ContentBundle\Tests\Helper\FormBuilderInterfaceExtender');
    $form->buildForm($formBuilder, array());
}

Now I have a FormBuilder instance, but PHP doesn’t see it as an instance of Symfony\Component\Form\FormBuilderInterface, so the type hinting in $form->buildForm() gives this error:

Argument 1 passed to Pwn\ContentBundle\Form\Type\PageType::buildForm() must be an instance of Symfony\Component\Form\FormBuilderInterface, instance of Mock_FormBuilderInterfaceExtender_3527f313 given

In other cases when I’ve used a mock object, type hinting and instanceof work correctly, but here it doesn’t:

var_dump($formBuilder);
var_dump($formBuilder instanceof \Symfony\Component\Form\FormBuilderInterface);

gives

class Mock_FormBuilderInterfaceExtender_76df04af#19 (1) {
  private $__phpunit_invocationMocker =>
  NULL
}
bool(false)

It seems I can make this work by mocking a class that implements the interface:

$formBuilder = $this->getMockBuilder('Symfony\Component\Form\FormBuilder')
                    ->disableOriginalConstructor()
                    ->getMock();

var_dump($formBuilder instanceof \Symfony\Component\Form\FormBuilderInterface);
// ^ gives bool(true)

However, should I be able to use the interface itself? Why does extending an interface ‘lose’ the type hinting?

Answer 1

Whenever you can’t test a Symfony2 interface, look in the component’s Tests directory to see if there is a mock specifically for testing. The test interfaces extend the real interface, and add any tweaks required to make phpunit run them.

In your case, try mocking Symfony\Component\Form\Tests\FormBuilderInterface instead.