public function testRefund()
{
/**
* @var LegacyRefundResponse $response
*/
$response = $this->gateway->refund(['refund_items' => [['out_trade_no' => '2016092021001003280286716852', 'amount' => '1', 'reason' => 'test']]])->send();
$this->assertTrue($response->isSuccessful());
$this->assertTrue($response->isRedirect());
$this->assertNotEmpty($response->getRedirectUrl());
}