[Mime] Fix email (de)serialization issues

Author: X-Coder264

Part/DataPart.php

@@ -156,7 +156,7 @@ public function __wakeup()
             throw new \BadMethodCallException('Cannot unserialize '.__CLASS__);
         }
         foreach (['body', 'charset', 'subtype', 'disposition', 'name', 'encoding'] as $name) {
-            if (null !== $this->_parent[$name] && !\is_string($this->_parent[$name])) {
+            if (null !== $this->_parent[$name] && !\is_string($this->_parent[$name]) && !$this->_parent[$name] instanceof File) {
                 throw new \BadMethodCallException('Cannot unserialize '.__CLASS__);
             }
             $r = new \ReflectionProperty(TextPart::class, $name);

Part/TextPart.php

@@ -226,7 +226,7 @@ private function chooseEncoding(): string
     public function __sleep(): array
     {
         // convert resources to strings for serialization
-        if (null !== $this->seekable || $this->body instanceof File) {
+        if (null !== $this->seekable) {
             $this->body = $this->getBody();
             $this->seekable = null;
         }

Tests/EmailTest.php

@@ -658,4 +658,34 @@ public function testBodyCache()
         $body2 = $email->getBody();
         $this->assertNotSame($body1, $body2, 'The two bodies must not reference the same object, so the body cache does not ensure that the hash for the DKIM signature is unique.');
     }
+
+    public function testAttachmentBodyIsPartOfTheSerializationEmailPayloadWhenUsingAttachMethod()
+    {
+        $email = new Email();
+        $email->attach(file_get_contents(__DIR__.\DIRECTORY_SEPARATOR.'Fixtures'.\DIRECTORY_SEPARATOR.'foo_attachment.txt') ?: '');
+
+        $this->assertTrue(str_contains(serialize($email), 'foo_bar_xyz_123'));
+    }
+
+    public function testAttachmentBodyIsNotPartOfTheSerializationEmailPayloadWhenUsingAttachFromPathMethod()
+    {
+        $email = new Email();
+        $email->attachFromPath(__DIR__.\DIRECTORY_SEPARATOR.'Fixtures'.\DIRECTORY_SEPARATOR.'foo_attachment.txt');
+
+        $this->assertFalse(str_contains(serialize($email), 'foo_bar_xyz_123'));
+    }
+
+    public function testEmailsWithAttachmentsWhichAreAFileInstanceCanBeUnserialized()
+    {
+        $email = new Email();
+        $email->attachFromPath(__DIR__.\DIRECTORY_SEPARATOR.'Fixtures'.\DIRECTORY_SEPARATOR.'foo_attachment.txt');
+
+        $email = unserialize(serialize($email));
+        $this->assertInstanceOf(Email::class, $email);
+
+        $attachments = $email->getAttachments();
+
+        $this->assertCount(1, $attachments);
+        $this->assertStringContainsString('foo_bar_xyz_123', $attachments[0]->getBody());
+    }
 }

Tests/Fixtures/foo_attachment.txt

@@ -0,0 +1 @@
+foo_bar_xyz_123