/**
  * @see HTTPS_Resource_Proxy::is_proxy_enabled()
  */
 function test_is_proxy_enabled()
 {
     $instance = new HTTPS_Resource_Proxy($this->plugin);
     $this->assertInternalType('bool', $instance->is_proxy_enabled());
     add_filter('https_resource_proxy_filtering_enabled', '__return_false', 5);
     $this->assertFalse($instance->is_proxy_enabled());
     add_filter('https_resource_proxy_filtering_enabled', '__return_true', 10);
     $this->assertTrue($instance->is_proxy_enabled());
 }