ENGCOM-7467: Fixes unstable email integration tests #27892

 - Merge Pull Request #27892 from hostep/magento2:fix-unstable-email-tests-part2
 - Merged commits:
   1. 3ec905f

Author: magento-engcom-team

dev/tests/integration/testsuite/Magento/Newsletter/Model/SubscriberTest.php

@@ -89,15 +89,15 @@ public function testUnsubscribeSubscribe(): void
         $this->assertEquals($subscriber, $subscriber->unsubscribe());
         $this->assertContains(
             'You have been unsubscribed from the newsletter.',
-            $this->transportBuilder->getSentMessage()->getRawMessage()
+            $this->transportBuilder->getSentMessage()->getBody()->getParts()[0]->getRawContent()
         );
         $this->assertEquals(Subscriber::STATUS_UNSUBSCRIBED, $subscriber->getSubscriberStatus());
         // Subscribe and verify
         $this->assertEquals(Subscriber::STATUS_SUBSCRIBED, $subscriber->subscribe('customer@example.com'));
         $this->assertEquals(Subscriber::STATUS_SUBSCRIBED, $subscriber->getSubscriberStatus());
         $this->assertContains(
             'You have been successfully subscribed to our newsletter.',
-            $this->transportBuilder->getSentMessage()->getRawMessage()
+            $this->transportBuilder->getSentMessage()->getBody()->getParts()[0]->getRawContent()
         );
     }
 
@@ -116,14 +116,14 @@ public function testUnsubscribeSubscribeByCustomerId(): void
         $this->assertEquals(Subscriber::STATUS_UNSUBSCRIBED, $subscriber->getSubscriberStatus());
         $this->assertContains(
             'You have been unsubscribed from the newsletter.',
-            $this->transportBuilder->getSentMessage()->getRawMessage()
+            $this->transportBuilder->getSentMessage()->getBody()->getParts()[0]->getRawContent()
         );
         // Subscribe and verify
         $this->assertSame($subscriber, $subscriber->subscribeCustomerById(1));
         $this->assertEquals(Subscriber::STATUS_SUBSCRIBED, $subscriber->getSubscriberStatus());
         $this->assertContains(
             'You have been successfully subscribed to our newsletter.',
-            $this->transportBuilder->getSentMessage()->getRawMessage()
+            $this->transportBuilder->getSentMessage()->getBody()->getParts()[0]->getRawContent()
         );
     }
 
@@ -143,7 +143,7 @@ public function testConfirm(): void
         $subscriber->confirm($subscriber->getSubscriberConfirmCode());
         $this->assertContains(
             'You have been successfully subscribed to our newsletter.',
-            $this->transportBuilder->getSentMessage()->getRawMessage()
+            $this->transportBuilder->getSentMessage()->getBody()->getParts()[0]->getRawContent()
         );
     }
 

dev/tests/integration/testsuite/Magento/ProductAlert/Model/EmailTest.php

@@ -101,8 +101,8 @@ public function testSend($isCustomerIdUsed)
         $this->_emailModel->send();
 
         $this->assertContains(
-            'Smith,',
-            $this->transportBuilder->getSentMessage()->getRawMessage()
+            'John Smith,',
+            $this->transportBuilder->getSentMessage()->getBody()->getParts()[0]->getRawContent()
         );
     }
 

dev/tests/integration/testsuite/Magento/ProductAlert/Model/ObserverTest.php

@@ -70,8 +70,8 @@ public function testProcess()
     {
         $this->observer->process();
         $this->assertContains(
-            'ohn Smith,',
-            $this->transportBuilder->getSentMessage()->getRawMessage()
+            'John Smith,',
+            $this->transportBuilder->getSentMessage()->getBody()->getParts()[0]->getRawContent()
         );
     }