public function throw_exception($e=null)
    {
        $e = $e ?: new \Exception();

        foreach ($this->policies as $policy) {
            $policy->check_method_throws($this->className, $this->methodName, $e, true);
        }

        $this->will(function () use ($e) {
            throw $e;
        });

        return $this;
    }