Fix setting mail header (#32272)

Author: driesvints

src/Illuminate/Mail/Mailer.php

@@ -324,20 +324,25 @@ protected function parseView($view)
      */
     protected function addContent($message, $view, $plain, $raw, $data)
     {
+        $header = $message->getContentType();
+
         if (isset($view)) {
-            $message->setBody($this->renderView($view, $data), 'text/html');
+            $message->setBody(
+                $this->renderView($view, $data),
+                $header && $header !== 'text/plain' ? $header : 'text/html'
+            );
         }
 
         if (isset($plain)) {
             $method = isset($view) ? 'addPart' : 'setBody';
 
-            $message->$method($this->renderView($plain, $data), 'text/plain');
+            $message->$method($this->renderView($plain, $data), $header ?: 'text/plain');
         }
 
         if (isset($raw)) {
             $method = (isset($view) || isset($plain)) ? 'addPart' : 'setBody';
 
-            $message->$method($raw, 'text/plain');
+            $message->$method($raw, $header ?: 'text/plain');
         }
     }
 

tests/Mail/MailMailerTest.php

@@ -36,6 +36,7 @@ public function testMailerSendSendsMessageWithProperViewContent()
         $message->shouldReceive('setFrom')->never();
         $this->setSwiftMailer($mailer);
         $message->shouldReceive('getSwiftMessage')->once()->andReturn($message);
+        $message->shouldReceive('getContentType')->once()->andReturn('');
         $mailer->getSwiftMailer()->shouldReceive('send')->once()->with($message, []);
         $mailer->send('foo', ['data'], function ($m) {
             $_SERVER['__mailer.test'] = $m;
@@ -57,6 +58,7 @@ public function testMailerSendSendsMessageWithProperViewContentUsingHtmlStrings(
         $message->shouldReceive('setFrom')->never();
         $this->setSwiftMailer($mailer);
         $message->shouldReceive('getSwiftMessage')->once()->andReturn($message);
+        $message->shouldReceive('getContentType')->once()->andReturn('');
         $mailer->getSwiftMailer()->shouldReceive('send')->once()->with($message, []);
         $mailer->send(['html' => new HtmlString('rendered.view'), 'text' => new HtmlString('rendered.text')], ['data'], function ($m) {
             $_SERVER['__mailer.test'] = $m;
@@ -77,6 +79,7 @@ public function testMailerSendSendsMessageWithProperViewContentUsingHtmlMethod()
         $message->shouldReceive('setFrom')->never();
         $this->setSwiftMailer($mailer);
         $message->shouldReceive('getSwiftMessage')->once()->andReturn($message);
+        $message->shouldReceive('getContentType')->once()->andReturn('');
         $mailer->getSwiftMailer()->shouldReceive('send')->once()->with($message, []);
         $mailer->html('rendered.view', function ($m) {
             $_SERVER['__mailer.test'] = $m;
@@ -99,6 +102,7 @@ public function testMailerSendSendsMessageWithProperPlainViewContent()
         $message->shouldReceive('setFrom')->never();
         $this->setSwiftMailer($mailer);
         $message->shouldReceive('getSwiftMessage')->once()->andReturn($message);
+        $message->shouldReceive('getContentType')->once()->andReturn('');
         $mailer->getSwiftMailer()->shouldReceive('send')->once()->with($message, []);
         $mailer->send(['foo', 'bar'], ['data'], function ($m) {
             $_SERVER['__mailer.test'] = $m;
@@ -121,6 +125,7 @@ public function testMailerSendSendsMessageWithProperPlainViewContentWhenExplicit
         $message->shouldReceive('setFrom')->never();
         $this->setSwiftMailer($mailer);
         $message->shouldReceive('getSwiftMessage')->once()->andReturn($message);
+        $message->shouldReceive('getContentType')->once()->andReturn('');
         $mailer->getSwiftMailer()->shouldReceive('send')->once()->with($message, []);
         $mailer->send(['html' => 'foo', 'text' => 'bar'], ['data'], function ($m) {
             $_SERVER['__mailer.test'] = $m;