Add IMessage::getSubject

Author: zbateson

src/IMessage.php

@@ -21,6 +21,12 @@
  */
 interface IMessage extends IMimePart
 {
+    /**
+     * Returns the subject of the message, retrieved from the 'Subject' header,
+     * or null if the message has none set.
+     */
+    public function getSubject() : ?string;
+
     /**
      * Returns the inline text/plain IMessagePart for a message.
      *

src/Message.php

@@ -101,6 +101,11 @@ public function isMime() : bool
         return ($contentType !== null || $mimeVersion !== null);
     }
 
+    public function getSubject() : ?string
+    {
+        return $this->getHeaderValue(HeaderConsts::SUBJECT);
+    }
+
     public function getTextPart(int $index = 0) : ?IMessagePart
     {
         return $this->getPart(

tests/MailMimeParser/IntegrationTests/EmailFunctionalTest.php

@@ -98,7 +98,7 @@ private function runEmailTestForMessage($message, array $props, $failMessage) :
         }
 
         if (isset($props['Subject'])) {
-            $this->assertEquals($props['Subject'], $message->getHeaderValue('subject'), $failMessage);
+            $this->assertEquals($props['Subject'], $message->getSubject(), $failMessage);
         }
 
         if (isset($props['Date'])) {