diff --git a/tests/Mail/MailMessageTest.php b/tests/Mail/MailMessageTest.php
index d5a2d90f2c40..c134159fc724 100755
--- a/tests/Mail/MailMessageTest.php
+++ b/tests/Mail/MailMessageTest.php
@@ -26,65 +26,65 @@ protected function setUp(): void
 
     public function testFromMethod()
     {
-        $this->assertInstanceOf(Message::class, $message = $this->message->from('foo@bar.baz', 'Foo'));
-        $this->assertEquals(new Address('foo@bar.baz', 'Foo'), $message->getSymfonyMessage()->getFrom()[0]);
+        $this->assertSame($this->message, $this->message->from('foo@bar.baz', 'Foo'));
+        $this->assertEquals(new Address('foo@bar.baz', 'Foo'), $this->message->getSymfonyMessage()->getFrom()[0]);
     }
 
     public function testSenderMethod()
     {
-        $this->assertInstanceOf(Message::class, $message = $this->message->sender('foo@bar.baz', 'Foo'));
-        $this->assertEquals(new Address('foo@bar.baz', 'Foo'), $message->getSymfonyMessage()->getSender());
+        $this->assertSame($this->message, $this->message->sender('foo@bar.baz', 'Foo'));
+        $this->assertEquals(new Address('foo@bar.baz', 'Foo'), $this->message->getSymfonyMessage()->getSender());
     }
 
     public function testReturnPathMethod()
     {
-        $this->assertInstanceOf(Message::class, $message = $this->message->returnPath('foo@bar.baz'));
-        $this->assertEquals(new Address('foo@bar.baz'), $message->getSymfonyMessage()->getReturnPath());
+        $this->assertSame($this->message, $this->message->returnPath('foo@bar.baz'));
+        $this->assertEquals(new Address('foo@bar.baz'), $this->message->getSymfonyMessage()->getReturnPath());
     }
 
     public function testToMethod()
     {
-        $this->assertInstanceOf(Message::class, $message = $this->message->to('foo@bar.baz', 'Foo'));
-        $this->assertEquals(new Address('foo@bar.baz', 'Foo'), $message->getSymfonyMessage()->getTo()[0]);
+        $this->assertSame($this->message, $this->message->to('foo@bar.baz', 'Foo'));
+        $this->assertEquals(new Address('foo@bar.baz', 'Foo'), $this->message->getSymfonyMessage()->getTo()[0]);
 
-        $this->assertInstanceOf(Message::class, $message = $this->message->to(['bar@bar.baz' => 'Bar']));
-        $this->assertEquals(new Address('bar@bar.baz', 'Bar'), $message->getSymfonyMessage()->getTo()[0]);
+        $this->assertSame($this->message, $this->message->to(['bar@bar.baz' => 'Bar']));
+        $this->assertEquals(new Address('bar@bar.baz', 'Bar'), $this->message->getSymfonyMessage()->getTo()[0]);
     }
 
     public function testToMethodWithOverride()
     {
-        $this->assertInstanceOf(Message::class, $message = $this->message->to('foo@bar.baz', 'Foo', true));
-        $this->assertEquals(new Address('foo@bar.baz', 'Foo'), $message->getSymfonyMessage()->getTo()[0]);
+        $this->assertSame($this->message, $this->message->to('foo@bar.baz', 'Foo', true));
+        $this->assertEquals(new Address('foo@bar.baz', 'Foo'), $this->message->getSymfonyMessage()->getTo()[0]);
     }
 
     public function testCcMethod()
     {
-        $this->assertInstanceOf(Message::class, $message = $this->message->cc('foo@bar.baz', 'Foo'));
-        $this->assertEquals(new Address('foo@bar.baz', 'Foo'), $message->getSymfonyMessage()->getCc()[0]);
+        $this->assertSame($this->message, $this->message->cc('foo@bar.baz', 'Foo'));
+        $this->assertEquals(new Address('foo@bar.baz', 'Foo'), $this->message->getSymfonyMessage()->getCc()[0]);
     }
 
     public function testBccMethod()
     {
-        $this->assertInstanceOf(Message::class, $message = $this->message->bcc('foo@bar.baz', 'Foo'));
-        $this->assertEquals(new Address('foo@bar.baz', 'Foo'), $message->getSymfonyMessage()->getBcc()[0]);
+        $this->assertSame($this->message, $this->message->bcc('foo@bar.baz', 'Foo'));
+        $this->assertEquals(new Address('foo@bar.baz', 'Foo'), $this->message->getSymfonyMessage()->getBcc()[0]);
     }
 
     public function testReplyToMethod()
     {
-        $this->assertInstanceOf(Message::class, $message = $this->message->replyTo('foo@bar.baz', 'Foo'));
-        $this->assertEquals(new Address('foo@bar.baz', 'Foo'), $message->getSymfonyMessage()->getReplyTo()[0]);
+        $this->assertSame($this->message, $this->message->replyTo('foo@bar.baz', 'Foo'));
+        $this->assertEquals(new Address('foo@bar.baz', 'Foo'), $this->message->getSymfonyMessage()->getReplyTo()[0]);
     }
 
     public function testSubjectMethod()
     {
-        $this->assertInstanceOf(Message::class, $message = $this->message->subject('foo'));
-        $this->assertSame('foo', $message->getSymfonyMessage()->getSubject());
+        $this->assertSame($this->message, $this->message->subject('foo'));
+        $this->assertSame('foo', $this->message->getSymfonyMessage()->getSubject());
     }
 
     public function testPriorityMethod()
     {
-        $this->assertInstanceOf(Message::class, $message = $this->message->priority(1));
-        $this->assertEquals(1, $message->getSymfonyMessage()->getPriority());
+        $this->assertSame($this->message, $this->message->priority(1));
+        $this->assertEquals(1, $this->message->getSymfonyMessage()->getPriority());
     }
 
     public function testBasicAttachment()