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Now that we've written some acceptance tests, functional tests are almost the same, with just one major difference: functional tests don't require a web server to run tests.

In simple terms we set $_REQUEST, $_GET and $_POST variables and then we execute application from a test. This may be valuable as functional tests are faster and provide detailed stack traces on failures.

Codeception can connect to different web frameworks which support functional testing: Symfony2, Laravel4, Yii2, Zend Framework and others. You just need to enable desired module in your functional suite config to start.

Modules for all of these frameworks share the same interface, and thus your tests are not bound to any one of them. This is a sample functional test.

<?php
$I = new FunctionalTester($scenario);
$I->amOnPage('/');
$I->click('Login');
$I->fillField('Username', 'Miles');
$I->fillField('Password', 'Davis');
$I->click('Enter');
$I->see('Hello, Miles', 'h1');
// $I->seeEmailIsSent() - special for Symfony2
?>

As you see you can use same tests for functional and acceptance testing.

Acceptance tests are usually much slower than functional tests. But functional tests are less stable as they run Codeception and application in one environment.

One of the common issues with functional tests is usage of PHP functions that deal with headers, sessions, cookies. As you know, header function triggers an error if it is executed more than once for the same header. In functional tests we run application multiple times, thus, we will get lots of trash errors in the result.

In functional testing unlike the traditional way, PHP application does not stop after it finished processing a request. As all requests run in one memory container they are not isolated. So if you see that your tests are mysteriously failing when they shouldn't - try to execute a single test. This will check if tests were isolated during run. Because it's really easy to spoil environment as all tests are run in shared memory. Keep your memory clean, avoid memory leaks and clean global and static variables.

You have a functional testing suite in tests/functional dir. To start you need to include one of the framework modules in suite config file: tests/functional.suite.yml. Below we provide simplified instructions for setting up functional tests with the most popular PHP frameworks.

To perform Symfony2 integrations you don't need to install any bundles or do any configuration changes. You just need to include the Symfony2 module into your test suite. If you also use Doctrine2, don't forget to include it too.

Example of functional.suite.yml

class_name: FunctionalTester
modules:
    enabled: [Symfony2, Doctrine2, TestHelper] 

By default this module will search for App Kernel in the app directory.

The module uses the Symfony Profiler to provide additional information and assertions.

See the full reference

Laravel module requires no configuration and can be easily set up.

class_name: FunctionalTester
modules:
    enabled: [Laravel4, TestHelper]

Yii2 tests are included in Basic and Advanced application templates. Follow Yii2 guides to start.

By itself Yii framework does not have an engine for functional testing. So Codeception is the first and the only functional testing framework for Yii. To use it with Yii include Yii1 module into config.

class_name: FunctionalTester
modules:
    enabled: [Yii1, TestHelper]

To avoid common pitfalls we discussed earlier, Codeception provides basic hooks over Yii engine. Please set them up following the installation steps in module reference.

Use ZF2 module to run functional tests inside Zend Framework 2.

class_name: FunctionalTester
modules:
    enabled: [ZF2, TestHelper]

The module for Zend Framework is highly inspired by ControllerTestCase class, used for functional testing with PHPUnit. It follows similar approaches for bootstrapping and cleaning up. To start using Zend Framework in your functional tests, include the ZF1 module.

Example of functional.suite.yml

class_name: FunctionalTester
modules:
    enabled: [ZF1, TestHelper] 

See the full reference

Phalcon1 module requires creating bootstrap file which returns instance of \Phalcon\Mvc\Application. To start writing functional tests with Phalcon support you should enable Phalcon1 module and provide path to this bootstrap file:

class_name: FunctionalTester
modules:
    enabled: [Phalcon1, FunctionalHelper]
    config:
        Phalcon1
            bootstrap: 'app/config/bootstrap.php'

See the full reference

Functional tests are written in the same manner as Acceptance Tests with PhpBrowser module enabled. All framework modules and PhpBrowser module share the same methods and the same engine.

Therefore we can open a web page with amOnPage command.

<?php
$I = new FunctionalTester;
$I->amOnPage('/login');
?>

We can click links to open web pages of application.

<?php
$I->click('Logout');
// click link inside .nav element
$I->click('Logout', '.nav');
// click by CSS
$I->click('a.logout');
// click with strict locator
$I->click(['class' => 'logout']);
?>

We can submit forms as well:

<?php
$I->submitForm('form#login', ['name' => 'john', 'password' => '123456']);
// alternatively
$I->fillField('#login input[name=name]', 'john');
$I->fillField('#login input[name=password]', '123456');
$I->click('Submit', '#login');
?>

And do assertions:

<?php
$I->see('Welcome, john');
$I->see('Logged in successfully', '.notice');
$I->seeCurrentUrlEquals('/profile/john');
?>

Framework modules also contain additional methods to access framework internals. For instance, Laravel4, Phalcon1, and Yii2 modules have seeRecord method which uses ActiveRecord layer to check that record exists in database. Laravel4 module also contains methods to do additional session checks. You may find seeSessionHasErrors useful when you test form validations.

Take a look at the complete reference for module you are using. Most of its methods are common for all modules but some of them are unique.

Also you can access framework globals inside a test or access Dependency Injection containers inside FunctionalHelper class.

<?php
class FunctionalHelper extends \Codeception\Module
{
    function doSomethingWithMyService()
    {
        $service = $this->getModule('Symfony2') // lookup for Symfony 2 module
            ->container // get current DI container
            ->get('my_service'); // access a service

        $service->doSomething();
    }
}
?>

We accessed Symfony2 internal kernel and took a service out of container. We also created custom method in FunctionalTester class which can be used in tests.

You can learn more about accessing framework you use by checking Public Properties section in the reference for the corresponding module.

By default Codeception uses E_ALL & ~E_STRICT & ~E_DEPRECATED error reporting level. In functional tests you might want to change this level depending on framework's error policy. The error reporting level can be set in the suite configuration file:

class_name: FunctionalTester
modules:
    enabled: [Yii1, TestHelper]
error_level: "E_ALL & ~E_STRICT & ~E_DEPRECATED"

error_level can be set globally in codeception.yml file.

Functional tests are great if you are using powerful frameworks. By using functional tests you can access and manipulate their internal state. This makes your tests shorter and faster. In other cases, if you don't use frameworks there is no practical reason to write functional tests. If you are using a framework other than the ones listed here, create a module for it and share it with community.