Govendor package negative testing

I have added stripe as a govendor package in my Go Chaincode (http://hyperledger-fabric.readthedocs.io/en/release-1.0/Style-guides/go-style.html) . As a part of negative testing , I would like to understand what would happen if the stripe goes down (which I understand would be rare) . Any leads on how I can do negative testing for govendor packages. I checked on stripe site , it was mentioned that if the stripe goes down , it would throw 5XX error(https://stripe.com/docs/api#errors)

Thanks in advance on the same.