So this is a weird one. It definitely feels like it's not the right solution, and it's apparent that something else might be going on.

`shoulda-context` with ruby 1.8.7 is dying on `respond_to?` with `@values` `nil`. They are using `instance_exec` and `respond_to?` is being called before the `StripeObject` sets up `@values`.

It's an odd one, but here is the build failure: https://travis-ci.org/stripe/stripe-ruby/jobs/17622167

Am open to suggestions!