Add ability to use formatter in email subject lines

src/Monolog/Handler/MailHandler.php

@@ -52,4 +52,16 @@ abstract class MailHandler extends AbstractProcessingHandler
     {
         $this->send((string) $record['formatted'], array($record));
     }
+
+    protected function getHighestRecord(array $records)
+    {
+        $highestRecord = null;
+        foreach ($records as $record) {
+            if ($highestRecord === null || $highestRecord['level'] < $record['level']) {
+                $highestRecord = $record;
+            }
+        }
+
+        return $highestRecord;
+    }
 }

src/Monolog/Handler/NativeMailerHandler.php

@@ -12,6 +12,7 @@
 namespace Monolog\Handler;
 
 use Monolog\Logger;
+use Monolog\Formatter\LineFormatter;
 
 /**
  * NativeMailerHandler uses the mail() function to send the emails
@@ -122,9 +123,16 @@ class NativeMailerHandler extends MailHandler
         if ($this->getContentType() == 'text/html' && false === strpos($headers, 'MIME-Version:')) {
             $headers .= 'MIME-Version: 1.0' . "\r\n";
         }
+
+        $subject = $this->subject;
+        if ($records) {
+            $subjectFormatter = new LineFormatter($this->subject);
+            $subject = $subjectFormatter->format($this->getHighestRecord($records));
+        }
+
         $parameters = implode(' ', $this->parameters);
         foreach ($this->to as $to) {
-            mail($to, $this->subject, $content, $headers, $parameters);
+            mail($to, $subject, $content, $headers, $parameters);
         }
     }
 

src/Monolog/Handler/SwiftMailerHandler.php

@@ -12,6 +12,7 @@
 namespace Monolog\Handler;
 
 use Monolog\Logger;
+use Monolog\Formatter\LineFormatter;
 
 /**
  * SwiftMailerHandler uses Swift_Mailer to send the emails
@@ -66,6 +67,11 @@ class SwiftMailerHandler extends MailHandler
             throw new \InvalidArgumentException('Could not resolve message as instance of Swift_Message or a callable returning it');
         }
 
+        if ($records) {
+            $subjectFormatter = new LineFormatter($message->getSubject());
+            $message->setSubject($subjectFormatter->format($this->getHighestRecord($records)));
+        }
+
         $message->setBody($content);
         $message->setDate(time());
 

tests/Monolog/Handler/NativeMailerHandlerTest.php

@@ -96,4 +96,16 @@ class NativeMailerHandlerTest extends TestCase
         $this->assertSame("From: $from\r\nContent-type: text/plain; charset=utf-8\r\n", $params[3]);
         $this->assertSame('', $params[4]);
     }
+
+    public function testMessageSubjectFormatting()
+    {
+        $mailer = new NativeMailerHandler('to@example.org', 'Alert: %level_name% %message%', 'from@example.org');
+        $mailer->handle($this->getRecord(Logger::ERROR, "Foo\nBar\r\n\r\nBaz"));
+        $this->assertNotEmpty($GLOBALS['mail']);
+        $this->assertInternalType('array', $GLOBALS['mail']);
+        $this->assertArrayHasKey('0', $GLOBALS['mail']);
+        $params = $GLOBALS['mail'][0];
+        $this->assertCount(5, $params);
+        $this->assertSame('Alert: ERROR Foo Bar  Baz', $params[1]);
+    }
 }

tests/Monolog/Handler/SwiftMailerHandlerTest.php

@@ -72,6 +72,30 @@ class SwiftMailerHandlerTest extends TestCase
         $handler->handleBatch($records);
     }
 
+    public function testMessageSubjectFormatting()
+    {
+        // Wire Mailer to expect a specific Swift_Message with a customized Subject
+        $messageTemplate = new \Swift_Message();
+        $messageTemplate->setSubject('Alert: %level_name% %message%');
+        $receivedMessage = null;
+
+        $this->mailer->expects($this->once())
+            ->method('send')
+            ->with($this->callback(function ($value) use (&$receivedMessage) {
+                $receivedMessage = $value;
+                return true;
+            }));
+
+        $handler = new SwiftMailerHandler($this->mailer, $messageTemplate);
+
+        $records = array(
+            $this->getRecord(Logger::EMERGENCY),
+        );
+        $handler->handleBatch($records);
+
+        $this->assertEquals('Alert: EMERGENCY test', $receivedMessage->getSubject());
+    }
+
     public function testMessageHaveUniqueId()
     {
         $messageTemplate = \Swift_Message::newInstance();