- Adds Amazon SES tests

- Refactors all API mailers
- Updates unit tests for all API mailers
- Adds Mailer router + tests

lib/Mailer/API/SendGrid.php

@@ -0,0 +1,51 @@
+<?php
+namespace MailPoet\Mailer\API;
+
+if(!defined('ABSPATH')) exit;
+
+class SendGrid {
+  function __construct($api_key, $from) {
+    $this->url = 'https://api.sendgrid.com/api/mail.send.json';
+    $this->api_key = $api_key;
+    $this->from = $from;
+  }
+
+  function send($newsletter, $subscriber) {
+    $this->newsletter = $newsletter;
+    $this->subscriber = $subscriber;
+    $result = wp_remote_post(
+      $this->url,
+      $this->request()
+    );
+    if(is_object($result) && get_class($result) === 'WP_Error') return false;
+    $result = json_decode($result['body'], true);
+    return (!isset($result['errors']) === true);
+  }
+
+  function getBody() {
+    $parameters = array(
+      'to' => $this->subscriber,
+      'from' => $this->from,
+      'subject' => $this->newsletter['subject'],
+      'html' => $this->newsletter['body']['html'],
+      'text' => $this->newsletter['body']['text']
+    );
+    return urldecode(http_build_query($parameters));
+  }
+
+  function auth() {
+    return 'Bearer ' . $this->api_key;
+  }
+
+  function request() {
+    return array(
+      'timeout' => 10,
+      'httpversion' => '1.1',
+      'method' => 'POST',
+      'headers' => array(
+        'Authorization' => $this->auth()
+      ),
+      'body' => $this->getBody()
+    );
+  }
+}