Autodetect content-types for email attachments (2.x)

This ports the safe parts of #9619 and updates the tests. Because
existing tests had to change and I was concerned about changing people's
email messages in a bugfix release I'm targetting 2.next with this
change.

Author: markstory

lib/Cake/Network/Email/CakeEmail.php

@@ -1081,6 +1081,9 @@ public function attachments($attachments = null) {
 					$name = basename($fileInfo['file']);
 				}
 			}
+			if (!isset($fileInfo['mimetype']) && function_exists('mime_content_type')) {
+				$fileInfo['mimetype'] = mime_content_type($fileInfo['file']);
+			}
 			if (!isset($fileInfo['mimetype'])) {
 				$fileInfo['mimetype'] = 'application/octet-stream';
 			}

lib/Cake/Test/Case/Network/Email/CakeEmailTest.php

@@ -821,7 +821,7 @@ public function testAttachments() {
 		$expected = array(
 			'basics.php' => array(
 				'file' => CAKE . 'basics.php',
-				'mimetype' => 'application/octet-stream'
+				'mimetype' => 'text/x-php'
 			)
 		);
 		$this->assertSame($expected, $this->CakeEmail->attachments());
@@ -837,9 +837,9 @@ public function testAttachments() {
 		$this->CakeEmail->addAttachments(array('other.txt' => CAKE . 'bootstrap.php', 'license' => CAKE . 'LICENSE.txt'));
 		$expected = array(
 			'basics.php' => array('file' => CAKE . 'basics.php', 'mimetype' => 'text/plain'),
-			'bootstrap.php' => array('file' => CAKE . 'bootstrap.php', 'mimetype' => 'application/octet-stream'),
-			'other.txt' => array('file' => CAKE . 'bootstrap.php', 'mimetype' => 'application/octet-stream'),
-			'license' => array('file' => CAKE . 'LICENSE.txt', 'mimetype' => 'application/octet-stream')
+			'bootstrap.php' => array('file' => CAKE . 'bootstrap.php', 'mimetype' => 'text/x-php'),
+			'other.txt' => array('file' => CAKE . 'bootstrap.php', 'mimetype' => 'text/x-php'),
+			'license' => array('file' => CAKE . 'LICENSE.txt', 'mimetype' => 'text/plain')
 		);
 		$this->assertSame($expected, $this->CakeEmail->attachments());
 
@@ -1075,7 +1075,7 @@ public function testSendNoTemplateWithAttachments() {
 			"\r\n" .
 			"\r\n" .
 			"--$boundary\r\n" .
-			"Content-Type: application/octet-stream\r\n" .
+			"Content-Type: text/x-php\r\n" .
 			"Content-Transfer-Encoding: base64\r\n" .
 			"Content-Disposition: attachment; filename=\"basics.php\"\r\n\r\n";
 		$this->assertContains($expected, $result['message']);
@@ -1156,7 +1156,7 @@ public function testSendNoTemplateWithAttachmentsAsBoth() {
 			"--alt-{$boundary}--\r\n" .
 			"\r\n" .
 			"--$boundary\r\n" .
-			"Content-Type: application/octet-stream\r\n" .
+			"Content-Type: text/plain\r\n" .
 			"Content-Transfer-Encoding: base64\r\n" .
 			"Content-Disposition: attachment; filename=\"VERSION.txt\"\r\n\r\n";
 		$this->assertContains($expected, $result['message']);
@@ -1208,7 +1208,7 @@ public function testSendWithInlineAttachments() {
 			"--alt-{$boundary}--\r\n" .
 			"\r\n" .
 			"--rel-$boundary\r\n" .
-			"Content-Type: application/octet-stream\r\n" .
+			"Content-Type: text/plain\r\n" .
 			"Content-Transfer-Encoding: base64\r\n" .
 			"Content-ID: <abc123>\r\n" .
 			"Content-Disposition: inline; filename=\"cake.png\"\r\n\r\n";
@@ -1250,7 +1250,7 @@ public function testSendWithInlineAttachmentsHtmlOnly() {
 			"\r\n" .
 			"\r\n" .
 			"--rel-$boundary\r\n" .
-			"Content-Type: application/octet-stream\r\n" .
+			"Content-Type: text/plain\r\n" .
 			"Content-Transfer-Encoding: base64\r\n" .
 			"Content-ID: <abc123>\r\n" .
 			"Content-Disposition: inline; filename=\"cake.png\"\r\n\r\n";
@@ -1289,7 +1289,7 @@ public function testSendWithNoContentDispositionAttachments() {
 			"\r\n" .
 			"\r\n" .
 			"--{$boundary}\r\n" .
-			"Content-Type: application/octet-stream\r\n" .
+			"Content-Type: text/plain\r\n" .
 			"Content-Transfer-Encoding: base64\r\n" .
 			"\r\n";
 
@@ -1707,11 +1707,11 @@ public function testSendAttachment() {
 		$this->CakeEmail->config(array());
 		$this->CakeEmail->attachments(array(CAKE . 'basics.php'));
 		$result = $this->CakeEmail->send('body');
-		$this->assertContains("Content-Type: application/octet-stream\r\nContent-Transfer-Encoding: base64\r\nContent-Disposition: attachment; filename=\"basics.php\"", $result['message']);
+		$this->assertContains("Content-Type: text/x-php\r\nContent-Transfer-Encoding: base64\r\nContent-Disposition: attachment; filename=\"basics.php\"", $result['message']);
 
 		$this->CakeEmail->attachments(array('my.file.txt' => CAKE . 'basics.php'));
 		$result = $this->CakeEmail->send('body');
-		$this->assertContains("Content-Type: application/octet-stream\r\nContent-Transfer-Encoding: base64\r\nContent-Disposition: attachment; filename=\"my.file.txt\"", $result['message']);
+		$this->assertContains("Content-Type: text/x-php\r\nContent-Transfer-Encoding: base64\r\nContent-Disposition: attachment; filename=\"my.file.txt\"", $result['message']);
 
 		$this->CakeEmail->attachments(array('file.txt' => array('file' => CAKE . 'basics.php', 'mimetype' => 'text/plain')));
 		$result = $this->CakeEmail->send('body');