Refactor confirmation email sending

Aspect mock stopped working for me so I had to create a separate service
for sending confirmation emails.

[MAILPOET-1522]

tests/unit/Subscribers/SendConfirmationEmailTest.php

@@ -0,0 +1,71 @@
+<?php
+
+namespace MailPoet\Subscribers;
+
+use AspectMock\Test as Mock;
+use Codeception\Stub;
+use MailPoet\Mailer\Mailer;
+use MailPoet\Models\Segment;
+use MailPoet\Models\Subscriber;
+use MailPoet\Models\SubscriberSegment;
+
+class SendConfirmationEmailTest extends \MailPoetTest {
+
+  function testItSendsConfirmationEmail() {
+    Mock::double('MailPoet\Subscription\Url', [
+      'getConfirmationUrl' => 'http://example.com'
+    ]);
+    $subscriber = Subscriber::create();
+    $subscriber->hydrate([
+      'first_name' => 'John',
+      'last_name' => 'Mailer',
+      'email' => 'john@mailpoet.com'
+    ]);
+
+    $mailer = Stub::makeEmpty(Mailer::class, [
+      'send' =>
+        Stub\Expected::once(function($email) {
+          expect($email['body']['html'])->contains('<strong>Test segment</strong>');
+          expect($email['body']['html'])->contains('<a target="_blank" href="http://example.com">Click here to confirm your subscription.</a>');
+        }),
+    ], $this);
+
+    $sender = new SendConfirmationEmail($mailer);
+
+
+    $segment = Segment::createOrUpdate(
+      array(
+        'name' => 'Test segment'
+      )
+    );
+    SubscriberSegment::subscribeToSegments(
+      $subscriber,
+      array($segment->id)
+    );
+
+    $sender->sendConfirmationEmail($subscriber);
+  }
+
+  function testItSetsErrorsWhenConfirmationEmailCannotBeSent() {
+    $subscriber = Subscriber::create();
+    $subscriber->hydrate([
+      'first_name' => 'John',
+      'last_name' => 'Mailer',
+      'email' => 'john@mailpoet.com'
+    ]);
+
+    $mailer = Stub::makeEmpty(Mailer::class, [
+      'send' =>
+        Stub\Expected::once(function () {
+          throw new \Exception('send error');
+        }),
+    ], $this);
+
+    $sender = new SendConfirmationEmail($mailer);
+
+    $sender->sendConfirmationEmail($subscriber);
+    // error is set on the subscriber model object
+    expect($subscriber->getErrors()[0])->equals('send error');
+  }
+
+}