Fix reply-to address when sending WP e-mails

This commit makes sure that the reply-to set for WP e-mails is
preserved when MailPoet is used to send them. Before this change,
MailPoet would ignore whatever was set for the reply-to field for WP
e-mails and use the same address as the one used for the sender instead.

I'm not super happy with the solution proposed here. I couldn't find an
easy way to simple set the reply-to address in the Mailer class and that
is why I'm calling Mailer::init() inside WordPressMailer.

[MAILPOET-3707]

lib/Mailer/WordPress/WordPressMailer.php

@@ -51,7 +51,15 @@ class WordPressMailer extends \PHPMailer {
     ];
 
     $sendWithMailer = function ($mailer) use ($email, $address, $extraParams) {
+      // we need to call Mailer::init() for every single WP e-mail to make sure reply-to is set
+      $replyTo = $this->getReplyToAddress();
+      $mailer->init(false, false, $replyTo);
+
       $result = $mailer->send($email, $address, $extraParams);
+
+      // make sure Mailer::init() is called again to clear the reply-to address that was just set if Mailer is used in another context
+      $mailer->mailerInstance = null;
+
       if (!$result['response']) {
         throw new \Exception($result['error']->getMessage());
       }
@@ -103,4 +111,25 @@ class WordPressMailer extends \PHPMailer {
     }
     return $result;
   }
+
+  private function getReplyToAddress() {
+    $replyToAddress = false;
+    $addresses = $this->getReplyToAddresses();
+
+    if (!empty($addresses)) {
+      // only one reply-to address supported by \MailPoet\Mailer
+      $address = array_shift($addresses);
+      $replyToAddress = [];
+
+      if ($address[1]) {
+        $replyToAddress['name'] = $address[1];
+      }
+
+      if ($address[0]) {
+        $replyToAddress['address'] = $address[0];
+      }
+    }
+
+    return $replyToAddress;
+  }
 }

tests/integration/Mailer/WordPress/WordpressMailerTest.php

@@ -6,6 +6,7 @@ use MailPoet\Entities\SubscriberEntity;
 use MailPoet\Mailer\Mailer;
 use MailPoet\Mailer\MailerError;
 use MailPoet\Mailer\MetaInfo;
+use MailPoet\Settings\SettingsController;
 use MailPoet\Subscribers\SubscribersRepository;
 
 // phpcs:disable Squiz.NamingConventions.ValidVariableName.MemberNotCamelCaps
@@ -268,6 +269,101 @@ class WordpressMailerTest extends \MailPoetTest {
     $wpMailer->send();
   }
 
+  /*
+   * Test for issue https://mailpoet.atlassian.net/browse/MAILPOET-3707
+   */
+  public function testItPreservesWPReplyTo() {
+    list($mailer, $fallbackMailer) = $this->getMailerInstancesForReplyToTests();
+
+    $wpMailer = new WordPressMailer($mailer, $fallbackMailer, new MetaInfo, $this->subscribersRepository);
+    $wpMailer->addAddress('email@example.com', 'Full Name');
+    $wpMailer->addReplyTo('reply-to@example.com', 'Reply To');
+    $wpMailer->From = 'email-from@example.com';
+    $wpMailer->Body = 'Body';
+    $wpMailer->send();
+
+    $mailer = $this->getPrivateProperty($wpMailer, 'mailer');
+
+    $this->assertEquals('reply-to@example.com', $mailer->replyTo['reply_to_email']);
+    $this->assertEquals('Reply To', $mailer->replyTo['reply_to_name']);
+  }
+
+  /*
+   * Test for issue https://mailpoet.atlassian.net/browse/MAILPOET-3707
+   */
+  public function testItSetsSenderAsReplyToWhenReplyToIsNotDefined() {
+    list($mailer, $fallbackMailer) = $this->getMailerInstancesForReplyToTests();
+
+    $wpMailer = new WordPressMailer($mailer, $fallbackMailer, new MetaInfo, $this->subscribersRepository);
+    $wpMailer->addAddress('email@example.com', 'Full Name');
+    $wpMailer->From = 'email-from@example.com';
+    $wpMailer->Body = 'Body';
+    $wpMailer->send();
+
+    $mailer = $this->getPrivateProperty($wpMailer, 'mailer');
+
+    $this->assertEquals('staff@mailinator.com', $mailer->replyTo['reply_to_email']);
+    $this->assertEquals('Sender', $mailer->replyTo['reply_to_name']);
+  }
+
+  /*
+   * Test for issue https://mailpoet.atlassian.net/browse/MAILPOET-3707
+   */
+  public function testItChangesReplyToEmailOnDifferentCalls() {
+    list($mailer, $fallbackMailer) = $this->getMailerInstancesForReplyToTests();
+
+    $wpMailer = new WordPressMailer($mailer, $fallbackMailer, new MetaInfo, $this->subscribersRepository);
+    $wpMailer->addAddress('email@example.com', 'Full Name');
+    $wpMailer->addReplyTo('reply-to@example.com', 'Reply To');
+    $wpMailer->From = 'email-from@example.com';
+    $wpMailer->Body = 'Body';
+    $wpMailer->send();
+
+    $mailer = $this->getPrivateProperty($wpMailer, 'mailer');
+
+    $this->assertEquals('reply-to@example.com', $mailer->replyTo['reply_to_email']);
+    $this->assertEquals('Reply To', $mailer->replyTo['reply_to_name']);
+
+    $wpMailer = new WordPressMailer($mailer, $fallbackMailer, new MetaInfo, $this->subscribersRepository);
+    $wpMailer->addAddress('email@example.com', 'Full Name');
+    $wpMailer->From = 'email-from@example.com';
+    $wpMailer->Body = 'Body';
+    $wpMailer->send();
+
+    $mailer = $this->getPrivateProperty($wpMailer, 'mailer');
+
+    $this->assertEquals('staff@mailinator.com', $mailer->replyTo['reply_to_email']);
+    $this->assertEquals('Sender', $mailer->replyTo['reply_to_name']);
+  }
+
+  private function getMailerInstancesForReplyToTests() {
+    $settings = SettingsController::getInstance();
+    $settings->set(
+      'sender',
+      [
+        'name' => 'Sender',
+        'address' => 'staff@mailinator.com',
+      ]
+    );
+
+    $mailer = new Mailer();
+
+    $fallbackMailer = $this->createMock(FallbackMailer::class);
+    $fallbackMailer->expects($this->never())->method('send');
+
+    return [
+      $mailer,
+      $fallbackMailer,
+    ];
+  }
+
+  private function getPrivateProperty($object, $property) {
+    $reflectedClass = new \ReflectionClass($object);
+    $reflection = $reflectedClass->getProperty($property);
+    $reflection->setAccessible(true);
+    return $reflection->getValue($object);
+  }
+
   public function _after() {
     $this->subscribersRepository->truncate();
   }