public function testFetchPurchase()
{
$request = $this->gateway->fetchPurchase(array('transactionReference' => 'abc123'));
$this->assertInstanceOf('\\Omnipay\\PayPal\\Message\\RestFetchPurchaseRequest', $request);
$this->assertSame('abc123', $request->getTransactionReference());
$data = $request->getData();
$this->assertEmpty($data);
}