protected function getHandler()
{
$resp = new \stdClass();
$resp->http_response_code = 200;
$this->mailgun = $this->prophesize(Mailgun::class);
$this->mailgun->sendMessage(Argument::cetera())->willReturn($resp);
return new MailgunHandler($this->mailgun->reveal(), 'www.example.org', 'default', 'mailgun');
}