Test that Premium hooks are executed [PREMIUM-2]

lib/WP/Hooks.php

@@ -0,0 +1,28 @@
+<?php
+namespace MailPoet\WP;
+
+class Hooks {
+  static function addFilter() {
+    return self::callWithFallback('add_filter', func_get_args());
+  }
+
+  static function applyFilters() {
+    return self::callWithFallback('apply_filters', func_get_args());
+  }
+
+  static function addAction() {
+    return self::callWithFallback('add_action', func_get_args());
+  }
+
+  static function doAction() {
+    return self::callWithFallback('do_action', func_get_args());
+  }
+
+  private static function callWithFallback($func, $args) {
+    $local_func = __NAMESPACE__ . '\\' . $func;
+    if(function_exists($local_func)) {
+      return call_user_func_array($local_func, $args);
+    }
+    return call_user_func_array($func, $args);
+  }
+}