public function testCredit_createsACreditUsingGivenCustomerId()
{
$customer = Braintree\Customer::createNoValidate(['creditCard' => ['number' => '5105105105105100', 'expirationDate' => '05/12']]);
$creditCard = $customer->creditCards[0];
$result = Braintree\Customer::credit($customer->id, ['amount' => '100.00']);
$this->assertTrue($result->success);
$this->assertEquals('100.00', $result->transaction->amount);
$this->assertEquals(Braintree\Transaction::CREDIT, $result->transaction->type);
$this->assertEquals($customer->id, $result->transaction->customerDetails->id);
$this->assertEquals($creditCard->token, $result->transaction->creditCardDetails->token);
}