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How to Unit Test your Forms

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How to Unit Test your Forms

The Form Component consists of 3 core objects: a form type (implementing FormTypeInterface), the Form and the FormView.

The only class that is usually manipulated by programmers is the form type class which serves as a form blueprint. It is used to generate the Form and the FormView. You could test it directly by mocking its interactions with the factory but it would be complex. It is better to pass it to FormFactory like it is done in a real application. It is simple to bootstrap and you can trust the Symfony components enough to use them as a testing base.

There is already a class that you can benefit from for simple FormTypes testing: TypeTestCase. It is used to test the core types and you can use it to test your types too.

Note

Depending on the way you installed your Symfony or Symfony Form Component the tests may not be downloaded. Use the --prefer-source option with composer if this is the case.

The Basics

The simplest TypeTestCase implementation looks like the following:

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// src/Acme/TestBundle/Tests/Form/Type/TestedTypeTests.php
namespace Acme\TestBundle\Tests\Form\Type;

use Acme\TestBundle\Form\Type\TestedType;
use Acme\TestBundle\Model\TestObject;
use Symfony\Component\Form\Tests\Extension\Core\Type\TypeTestCase;

class TestedTypeTest extends TypeTestCase
{
    public function testBindValidData()
    {
        $formData = array(
            'test' => 'test',
            'test2' => 'test2',
        );

        $type = new TestedType();
        $form = $this->factory->create($type);

        $object = new TestObject();
        $object->fromArray($formData);

        $form->bind($formData);

        $this->assertTrue($form->isSynchronized());
        $this->assertEquals($object, $form->getData());

        $view = $form->createView();
        $children = $view->children;

        foreach (array_keys($formData) as $key) {
            $this->assertArrayHasKey($key, $children);
        }
    }
}

So, what does it test? Let's explain it line by line.

First you verify if the FormType compiles. This includes basic class inheritance, the buildForm function and options resolution. This should be the first test you write:

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$type = new TestedType();
$form = $this->factory->create($type);

This test checks that none of your data transformers used by the form failed. The isSynchronized`() method is only set to false if a data transformer throws an exception:

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$form->bind($formData);
$this->assertTrue($form->isSynchronized());

Note

Don't test the validation: it is applied by a listener that is not active in the test case and it relies on validation configuration. Instead, unit test your custom constraints directly.

Next, verify the binding and mapping of the form. The test below checks if all the fields are correctly specified:

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$this->assertEquals($object, $form->getData());

Finally, check the creation of the FormView. You should check if all widgets you want to display are available in the children property:

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$view = $form->createView();
$children = $view->children;

foreach (array_keys($formData) as $key) {
    $this->assertArrayHasKey($key, $children);
}

Adding a Type your Form depends on

Your form may depend on other types that are defined as services. It might look like this:

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// src/Acme/TestBundle/Form/Type/TestedType.php

// ... the buildForm method
$builder->add('acme_test_child_type');

To create your form correctly, you need to make the type available to the form factory in your test. The easiest way is to register it manually before creating the parent form:

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// src/Acme/TestBundle/Tests/Form/Type/TestedTypeTests.php
namespace Acme\TestBundle\Tests\Form\Type;

use Acme\TestBundle\Form\Type\TestedType;
use Acme\TestBundle\Model\TestObject;
use Symfony\Component\Form\Tests\Extension\Core\Type\TypeTestCase;

class TestedTypeTest extends TypeTestCase
{
    public function testBindValidData()
    {
        $this->factory->addType(new TestChildType());

        $type = new TestedType();
        $form = $this->factory->create($type);

        // ... your test
    }
}

Caution

Make sure the child type you add is well tested. Otherwise you may be getting errors that are not related to the form you are currently testing but to its children.

Adding custom Extensions

It often happens that you use some options that are added by form extensions. One of the cases may be the ValidatorExtension with its invalid_message option. The TypeTestCase loads only the core form extension so an "Invalid option" exception will be raised if you try to use it for testing a class that depends on other extensions. You need add those extensions to the factory object:

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// src/Acme/TestBundle/Tests/Form/Type/TestedTypeTests.php
namespace Acme\TestBundle\Tests\Form\Type;

use Acme\TestBundle\Form\Type\TestedType;
use Acme\TestBundle\Model\TestObject;
use Symfony\Component\Form\Tests\Extension\Core\Type\TypeTestCase;

class TestedTypeTest extends TypeTestCase
{
    protected function setUp()
    {
        parent::setUp();

        $this->factory = Forms::createFormFactoryBuilder()
            ->addTypeExtension(
                new FormTypeValidatorExtension(
                    $this->getMock('Symfony\Component\Validator\ValidatorInterface')
                )
            )
            ->addTypeGuesser(
                $this->getMockBuilder(
                    'Symfony\Component\Form\Extension\Validator\ValidatorTypeGuesser'
                )
                    ->disableOriginalConstructor()
                    ->getMock()
            )
            ->getFormFactory();

        $this->dispatcher = $this->getMock('Symfony\Component\EventDispatcher\EventDispatcherInterface');
        $this->builder = new FormBuilder(null, null, $this->dispatcher, $this->factory);
    }

    // ... your tests
}

Testing against different Sets of Data

If you are not familiar yet with PHPUnit's data providers, this might be a good opportunity to use them:

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// src/Acme/TestBundle/Tests/Form/Type/TestedTypeTests.php
namespace Acme\TestBundle\Tests\Form\Type;

use Acme\TestBundle\Form\Type\TestedType;
use Acme\TestBundle\Model\TestObject;
use Symfony\Component\Form\Tests\Extension\Core\Type\TypeTestCase;

class TestedTypeTest extends TypeTestCase
{

    /**
     * @dataProvider getValidTestData
     */
    public function testForm($data)
    {
        // ... your test
    }

    public function getValidTestData()
    {
        return array(
            array(
                'data' => array(
                    'test' => 'test',
                    'test2' => 'test2',
                ),
            ),
            array(
                'data' => array(),
            ),
            array(
                'data' => array(
                    'test' => null,
                    'test2' => null,
                ),
            ),
        );
    }
}

The code above will run your test three times with 3 different sets of data. This allows for decoupling the test fixtures from the tests and easily testing against multiple sets of data.

You can also pass another argument, such as a boolean if the form has to be synchronized with the given set of data or not etc.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.