added FileMailer implementation of mailer interface

extensions/swiftmailer/FileMailer.php

+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yii\swiftmailer;
+
+use yii\helpers\FileHelper;
+use yii\mail\BaseMailer;
+use Yii;
+
+/**
+ * FileMailer implements a mailer that saves mails as files under runtime directory.
+ *
+ * To use FileMailer, you should configure it in the application configuration like the following,
+ *
+ * ~~~
+ * 'components' => array(
+ *     ...
+ *     'email' => array(
+ *         'class' => 'yii\swiftmailer\FileMailer'
+ *     ),
+ *     ...
+ * ),
+ * ~~~
+ *
+ * To send an email, you may use the following code:
+ *
+ * ~~~
+ * Yii::$app->mail->compose('contact/html', ['contactForm' => $form])
+ *     ->setFrom('from@domain.com')
+ *     ->setTo($form->email)
+ *     ->setSubject($form->subject)
+ *     ->send();
+ * ~~~
+ *
+ * @author Dmitry Erofeev <dmeroff@gmail.com>
+ * @since 2.0
+ */
+class FileMailer extends BaseMailer
+{
+	/**
+	 * @var string message default class name.
+	 */
+	public $messageClass = 'yii\swiftmailer\Message';
+
+	/**
+	 * @var string The path under which mail files will be written. Defaults to "@app/runtime/mail".
+	 */
+	protected $path;
+
+	/**
+	 * @var callable Callback that will be used to generate name of the message to save.
+	 */
+	protected $callback;
+
+	/**
+	 * Sets path under which mail files will be written.
+	 * Any trailing '/' and '\' characters in the given path will be trimmed.
+	 *
+	 * @param $path
+	 * @throws \InvalidArgumentException
+	 */
+	public function setPath($path)
+	{
+		$path = Yii::getAlias($path);
+		if (!is_dir($path) || !is_writable($path)) {
+			throw new \InvalidArgumentException('Filemailer::setPath expects a valid path in which to write mail files');
+		}
+
+		$this->path = rtrim($path, '\\/');
+	}
+
+	/**
+	 * Gets path under which mail files will be written.
+	 *
+	 * @return string
+	 */
+	public function getPath()
+	{
+		if ($this->path == null) {
+			$path = Yii::getAlias('@app/runtime/mail');
+			if (!is_dir($path)) {
+				FileHelper::createDirectory($path);
+			}
+			$this->setPath($path);
+		}
+
+		return $this->path;
+	}
+
+	/**
+	 * Sets callback that will be used to generate name of the message to save.
+	 *
+	 * @param callable $callback
+	 */
+	public function setCallback(callable $callback)
+	{
+		$this->callback = $callback;
+	}
+
+	/**
+	 * Gets callback that will be used to generate name of the message to save.
+	 *
+	 * @return callable
+	 */
+	public function getCallback()
+	{
+		if ($this->callback == null) {
+			$this->setCallback(function () {
+				return uniqid('Message_') . '.txt';
+			});
+		}
+
+		return $this->callback;
+	}
+
+	/**
+	 * @inheritdoc
+	 */
+	public function send($message)
+	{
+		$address = $message->getTo();
+		if (is_array($address)) {
+			$address = implode(', ', array_keys($address));
+		}
+		Yii::trace('Sending email "' . $message->getSubject() . '" to "' . $address . '"', __METHOD__);
+
+		$filename = $this->getPath() . DIRECTORY_SEPARATOR . call_user_func($this->getCallback());
+
+		return file_put_contents($filename, $message->toString()) !== false;
+	}
+}
\ No newline at end of file

extensions/swiftmailer/README.md

@@ -16,6 +16,20 @@ return [
 ];
 ```
 
+Extension also includes `FileMailer` that saves mails as files under runtime directory.
+It can be useful during development. To use it add the following code in your application configuration:
+
+```php
+return [
+	//....
+	'components' => [
+		'mail' => [
+			'class' => 'yii\swiftmailer\FileMailer',
+		],
+	],
+];
+```
+
 You can then send an email as follows:
 
 ```php

extensions/swiftmailer/composer.json

@@ -15,6 +15,10 @@
 		{
 			"name": "Paul Klimov",
 			"email": "klimov.paul@gmail.com"
+		},
+        {
+            "name": "Dmitry Erofeev",
+            "email": "dmeroff@gmail.com"
         }
 	],
 	"minimum-stability": "dev",

tests/unit/extensions/swiftmailer/FileMailerTest.php

+<?php
+
+namespace yiiunit\extensions\swiftmailer;
+
+require __DIR__ . '/../../../../extensions/swiftmailer/FileMailer.php';
+
+use yii\swiftmailer\FileMailer;
+use yiiunit\VendorTestCase;
+
+/**
+ * @group vendor
+ * @group mail
+ * @group swiftmailer
+ */
+class FileMailerTest extends VendorTestCase
+{
+	public function setUp()
+	{
+		$this->mockApplication([
+			'components' => [
+				'mail' => $this->createTestEmailComponent()
+			]
+		]);
+	}
+
+	/**
+	 * @return FileMailer test email component instance.
+	 */
+	protected function createTestEmailComponent()
+	{
+		$component = new FileMailer([
+			'callback' => function () {
+				return 'Message_test.txt';
+			}
+		]);
+
+		return $component;
+	}
+
+	public function testConfigurePath()
+	{
+		$mailer = new FileMailer();
+		$this->assertEquals(\Yii::getAlias('@app/runtime/mail'), $mailer->getPath());
+		$mailer->setPath('@yiiunit/runtime/');
+		$this->assertEquals(\Yii::getAlias('@yiiunit/runtime'), $mailer->getPath());
+	}
+
+	public function testSend()
+	{
+		$message = \Yii::$app->mail->compose()
+			->setTo('tester@example.com')
+			->setFrom('admin@example.com')
+			->setSubject('Just a test')
+			->setHtmlBody('This is html body');
+		$message->send();
+		$this->assertEquals(
+			$message->toString(),
+			file_get_contents(\Yii::$app->getRuntimePath() . '/mail/Message_test.txt')
+		);
+	}
+}
+ 
\ No newline at end of file