# Unit Tests

Codeception uses PHPUnit as a backend for running tests. Thus, any PHPUnit test can be added to Codeception test suite and then executed.
If you ever wrote a PHPUnit test then do it just as you did before. 
Codeception adds some nice helpers to simplify common tasks.

The basics of unit tests are skipped here, instead you will get a basic knowledge of what features Codeception adds to unit tests.

__To say it again: you don't need to install PHPUnit to run its tests. Codeception can run them too.__

## Creating Test

Codeception have nice generators to simplify test creation.
You can start with generating a classical PHPUnit test extending `\PHPUnit_Framework_TestCase` class.
This can be done by this command:

```bash
php codecept generate:phpunit unit Example
```

Codeception has its addons to standard unit tests, so let's try them.
We need another command to create Codeception-powered unit tests.

```bash
php codecept generate:test unit Example
```

Both tests will create a new `ExampleTest` file located in `tests/unit` directory.

As always, you can run the just created test with this command:

```bash
php codecept run unit ExampleTest
```

or simply run the whole set of unit tests with this:

```bash
php codecept run unit
```

A test created by `generate:test` command will look like this:

```php
<?php
use Codeception\Util\Stub;

class ExampleTest extends \Codeception\Test\Unit
{
   /**
    * @var UnitTester
    */
    protected $tester;

    // executed before each test
    protected function _before()
    {
    }

    // executed after each test
    protected function _after()
    {
    }
}
```

This class has predefined `_before` and `_after` methods to start with. You can use them to create a tested object before each test, and destroy it afterwards.

As you see, unlike in PHPUnit, `setUp` and `tearDown` methods are replaced with their aliases: `_before`, `_after`.

The actual `setUp` and `tearDown` were implemented by parent class `\Codeception\TestCase\Test` and set up the UnitTester class to have all the cool actions from Cept-files to be run as a part of unit tests. Just like in acceptance and functional tests you can choose the proper modules for `UnitTester` class in `unit.suite.yml` configuration file.


```yaml
# Codeception Test Suite Configuration

# suite for unit (internal) tests.
class_name: UnitTester
modules:
    enabled: 
        - Asserts
        - \Helper\Unit
```

## Classical Unit Testing

Unit tests in Codeception are written in absolutely the same way as it is done in PHPUnit:

```php
<?php
class UserTest extends \Codeception\Test\Unit
{
    public function testValidation()
    {
        $user = User::create();

        $user->username = null;
        $this->assertFalse($user->validate(['username']));

        $user->username = 'toolooooongnaaaaaaameeee';
        $this->assertFalse($user->validate(['username']));

        $user->username = 'davert';
        $this->assertTrue($user->validate(['username']));           
    }
}
```


### Using Modules

As in scenario-driven functional or acceptance tests you can access Actor class methods. If you write integration tests, it may be useful to include `Db` module for database testing. 

```yaml
# Codeception Test Suite Configuration

# suite for unit (internal) tests.
class_name: UnitTester
modules:
    enabled: 
        - Asserts
        - Db
        - \Helper\Unit
```

To access UnitTester methods you can use `UnitTester` property in a test.

### Testing Database

Let's see how you can do some database testing:

```php
<?php
function testSavingUser()
{
    $user = new User();
    $user->setName('Miles');
    $user->setSurname('Davis');
    $user->save();
    $this->assertEquals('Miles Davis', $user->getFullName());
    $this->tester->seeInDatabase('users', ['name' => 'Miles', 'surname' => 'Davis']);
}
```

To enable the database functionality in the unit tests please make sure the `Db` module is part of the enabled module list in the unit.suite.yml configuration file. 
The database will be cleaned and populated after each test, as it happens for acceptance and functional tests.
If it's not your required behavior, please change the settings of `Db` module for the current suite.

### Interacting with the Framework

Probably you should not access your database directly if your project already uses ORM for database interactions.
Why not use the ORM directly inside your tests? Let's try to write a test using Laravel's ORM Eloquent, for this we need configured Laravel5 module. We won't need its web interaction methods like `amOnPage` or `see`, so let's enable only ORM part of it:

```yaml
class_name: UnitTester
modules:
    enabled:
        - Asserts
        - Laravel5:
            part: ORM
        - \Helper\Unit
```

We included Laravel5 module as we did for functional testing. Let's see how we can use it for integration tests:

```php
<?php
function testUserNameCanBeChanged()
{
    // create a user from framework, user will be deleted after the test
    $id = $this->tester->haveRecord('users', ['name' => 'miles']);
    // access model
    $user = User::find($id);
    $user->setName('bill');
    $user->save();
    $this->assertEquals('bill', $user->getName());
    // verify data was saved using framework methods
    $this->tester->seeRecord('users', ['name' => 'bill']);
    $this->tester->dontSeeRecord('users', ['name' => 'miles']);
}
```

The very similar approach can be used to all frameworks that have ORM implementing ActiveRecord pattern.
These are Yii2 and Phalcon, they have methods `haveRecord`, `seeRecord`, `dontSeeRecord` working in the same manner. They also should be included with specifying `part: ORM` in order to not use functional testing actions.

In case you are using Symfony with Doctrine you may not enable Symfony itself but use only Doctrine2 only:

```yaml
class_name: UnitTester
modules:
    enabled:
        - Asserts
        - Doctrine2:
            depends: Symfony
        - \Helper\Unit
```

In this case you can use methods from Doctrine2 module, while Doctrine itself uses Symfony module to establish connection to database. In this case a test may look like:

```php
<?php
function testUserNameCanBeChanged()
{
    // create a user from framework, user will be deleted after the test
    $id = $this->tester->haveInRepository('Acme\DemoBundle\Entity\User', ['name' => 'miles']);
    // get entity manager by accessing module
    $em = $this->getModule('Doctrine2')->em;
    // get real user
    $user = $em->find('Acme\DemoBundle\Entity\User', $id);
    $user->setName('bill');
    $em->persist($user);
    $em->flush();
    $this->assertEquals('bill', $user->getName());
    // verify data was saved using framework methods
    $this->tester->seeInRepository('Acme\DemoBundle\Entity\User', ['name' => 'bill']);
    $this->tester->dontSeeInRepository('Acme\DemoBundle\Entity\User', ['name' => 'miles']);
}
```

In both examples you should not be worried about the data persistence between tests.
Doctrine2 module as well as Laravel5 module will clean up created data at the end of a test.
This is done by wrapping a test in a transaction and rolling it back afterwards. 

### Accessing Module

Codeception allows you to access properties and methods of all modules defined for this suite. Unlike using the UnitTester class for this purpose, using module directly grants you access to all public properties of that module.

We already demonstrated this case in previous code piece where we accessed Entity Manager from a Doctrine2 module

```php
<?php
/** @var Doctrine\ORM\EntityManager */
$em = $this->getModule('Doctrine2')->em;
```

If you use `Symfony` module, here is the way you can access Symfony container:

```php
<?php
/** @var Symfony\Component\DependencyInjection\Container */
$container = $this->getModule('Symfony')->container;
```

The same can be done for all public properties of an enabled module. Accessible properties are listed in the module reference

## BDD Specification Testing

When writing tests you should prepare them for constant changes in your application. Tests should be easy to read and maintain. If a specification to your application is changed, your tests should be updated as well. If you don't have a convention inside your team on documenting tests, you will have issues figuring out what tests were affected by introduction of a new feature.

That's why it's pretty important not just to cover your application with unit tests, but make unit tests self-explanatory. We do this for scenario-driven acceptance and functional tests, and we should do this for unit and integration tests as well.

For this case we have a stand-alone project [Specify](https://github.com/Codeception/Specify) (which is included in phar package) for writing specifications inside unit tests.

```php
<?php
class UserTest extends \Codeception\Test\Unit
{
    use \Codeception\Specify;

    private $user;

    public function testValidation()
    {
        $this->user = User::create();

        $this->specify("username is required", function() {
            $this->user->username = null;
            $this->assertFalse($this->user->validate(['username']));
        });

        $this->specify("username is too long", function() {
            $this->user->username = 'toolooooongnaaaaaaameeee';
            $this->assertFalse($this->user->validate(['username']));
        });

        $this->specify("username is ok", function() {
            $this->user->username = 'davert';
            $this->assertTrue($this->user->validate(['username']));
        });
    }
}
```

Using `specify` codeblocks you can describe any piece of test. This makes tests much cleaner and understandable for everyone in your team.

Code inside `specify` blocks is isolated. In the example above any change to `$this->user` (as any other object property), will not be reflected in other code blocks. Specify uses deep and shallow cloning strategies to save objects between isolated scopes. The downsides of this approach is increased memory consumption (on deep cloning) or not complete isolation when shallow cloning is used. Please make sure you understand how [Specify](https://github.com/Codeception/Specify) works and how to configure it before using it in your tests.

Also you may add [Codeception\Verify](https://github.com/Codeception/Verify) for BDD-style assertions. This tiny library adds more readable assertions, which is quite nice, if you are always confused of which argument in `assert` calls is expected and which one is actual.

```php
<?php
verify($user->getName())->equals('john');

```


## Cest

Alternatively to testcases extended from `PHPUnit_Framework_TestCase` you may use Codeception-specific Cest format. It does not require to be extended from any other class. All public methods of this class are tests.

The example above can be rewritten in scenario-driven manner like this:

```php
<?php
class UserCest
{
    public function validateUser(UnitTester $t)
    {
        $user = $t->createUser();
        $user->username = null;
        $t->assertFalse($user->validate(['username']); 

        $user->username = 'toolooooongnaaaaaaameeee';
        $t->assertFalse($user->validate(['username']));

        $user->username = 'davert';
        $t->assertTrue($user->validate(['username']));

        $t->seeInDatabase('users', ['name' => 'Miles', 'surname' => 'Davis']);
    }
}
```

For unit testing you may include `Asserts` module, that adds regular assertions to UnitTester which you may access from `$t` variable.

```yaml
# Codeception Test Suite Configuration

# suite for unit (internal) tests.
class_name: UnitTester
modules:
    enabled: 
        - Asserts
        - Db
        - \Helper\Unit
```

[Learn more about Cest format](http://codeception.com/docs/07-AdvancedUsage#Cest-Classes).

<div class="alert alert-info">
It may look like Cest format is too simple for writing tests. It doesn't provide assertion methods,
methods to create mocks and stubs or even accessing the module with `getModule`, as we did in example above.
However Cest format is better at separating concerns. Test code does not interfere with support code, provided by `UnitTester` object. All additional actions you may need in your unit/integration tests you can implement in `Helper\Unit` class.
</div>

To check your code for exception you can use `expectException` method from `Asserts` module. Unlike similar method from PHPUnit this method asserts exception was thrown inside a test. For this code executing exception is wrapped inside a closure.

```php
<?php
$t->expectException(Exception::class, function() {
   throw new Exception; 
});
```

## Stubs

Codeception provides a tiny wrapper over PHPUnit mocking framework to create stubs easily. Include `\Codeception\Util\Stub` to start creating dummy objects.

In this example we instantiate object without calling a constructor and replace `getName` method to return value *john*.

```php
<?php
$user = Stub::make('User', ['getName' => 'john']);
$name = $user->getName(); // 'john'
```

Stubs are created with PHPUnit's mocking framework. Alternatively you can use [Mockery](https://github.com/padraic/mockery) (with [Mockery module](https://github.com/Codeception/MockeryModule)), [AspectMock](https://github.com/Codeception/AspectMock) or others.

Full reference on Stub util class can be found [here](/docs/reference/Stub).

## Conclusion

PHPUnit tests are first-class citizens in test suites. Whenever you need to write and execute unit tests, you don't need to install PHPUnit, but use Codeception to execute them. Some nice features can be added to common unit tests by integrating Codeception modules. For the most of unit and integration testing PHPUnit tests are just enough. They are fast and easy to maintain.