FakeSoapClient.php

<?php

class FakeSoapClient extends \SoapClient
{
    protected $response;
    protected $customizer;

    public static function wsdl($wsdl)
    {
        return new self($wsdl);
    }

    public function withResponse($response, $customizer = null)
    {
        $this->customizer = $customizer;
        $this->response = $response;

        return $this;
    }

    public function __doRequest($request, $location, $action, $version, $one_way = null)
    {
        return $this->response;
    }

    public function __call($name, $arguments)
    {
        $response = parent::__call($name, $arguments);

        if (is_callable(($this->customizer))) {
            ($this->customizer)($response);
        }

        return $response;
    }
}