Fixes unstable email integration tests, by decoding the raw contents which had a maximum line length of 76 to a parseable string without a maximum line length, so there is no chance a particular string used in an assertion is getting splitted over multiple lines.

Author: hostep

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

@@ -100,7 +100,7 @@ public function testConfirm()
 
         $this->assertContains(
             'You have been successfully subscribed to our newsletter.',
-            $transportBuilder->getSentMessage()->getRawMessage()
+            $transportBuilder->getSentMessage()->getBody()->getParts()[0]->getRawContent()
         );
     }
 }

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

@@ -102,7 +102,7 @@ public function testSend($isCustomerIdUsed)
 
         $this->assertContains(
             'John Smith,',
-            $this->transportBuilder->getSentMessage()->getRawMessage()
+            $this->transportBuilder->getSentMessage()->getBody()->getParts()[0]->getRawContent()
         );
     }
 

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

@@ -71,7 +71,7 @@ public function testProcess()
         $this->observer->process();
         $this->assertContains(
             'John Smith,',
-            $this->transportBuilder->getSentMessage()->getRawMessage()
+            $this->transportBuilder->getSentMessage()->getBody()->getParts()[0]->getRawContent()
         );
     }
 
@@ -117,7 +117,7 @@ public function testProcessPortuguese()
 
         // dispatch process() method and check sent message
         $this->observer->process();
-        $message = $this->transportBuilder->getSentMessage()->getRawMessage();
+        $message = $this->transportBuilder->getSentMessage()->getBody()->getParts()[0]->getRawContent();
         $expectedText = array_shift($translation);
         $this->assertContains('/frontend/Magento/luma/pt_BR/', $message);
         $this->assertContains(substr($expectedText, 0, 50), $message);

dev/tests/integration/testsuite/Magento/Wishlist/Controller/IndexTest.php

@@ -175,7 +175,7 @@ public function testSendAction()
             \Magento\TestFramework\Mail\Template\TransportBuilderMock::class
         );
 
-        $actualResult = quoted_printable_decode($transportBuilder->getSentMessage()->getRawMessage());
+        $actualResult = $transportBuilder->getSentMessage()->getBody()->getParts()[0]->getRawContent();
 
         $this->assertStringMatchesFormat(
             '%A' . $this->_customerViewHelper->getCustomerName($this->_customerSession->getCustomerDataObject())