CI is failing for a number of Ruby versions because shoulda is pulling
in should-matchers, which then pulls in activesupport. activesupport's
new 5.0.0 version is being picked up, and that requires at least Ruby
2.2.2.
Luckily the solution is easy, we're not using shoulda-matchers, only
shoulda-context, so just tighten up our dependencies a little and the
problem goes away.
I'm not sure exactly what changed here (did we change the `$VERBOSE`
setting?), but I'm not seeing a whole lot of warnings when running the
test suites locally and in CI. For example:
```
Started
........................................./home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
............../home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
../home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
......../home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
.../home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
........./home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
...
..../home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
....../home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
..../home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
......./home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
........./home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
........../home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
................./home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
.../home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
..../home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
....../home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
..........
........./home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
....../home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
......../home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
......../home/travis/build/stripe/stripe-ruby/lib/stripe/api_operations/list.rb:6: warning: instance variable @opts not initialized
............./home/travis/build/stripe/stripe-ruby/lib/stripe/stripe_object.rb:35: warning: instance variable @values not initialized
./home/travis/build/stripe/stripe-ruby/lib/stripe/stripe_object.rb:35: warning: instance variable @values not initialized
...................../home/travis/build/stripe/stripe-ruby/lib/stripe/transfer.rb:8: warning: instance variable @api_key not initialized
..............
..
Finished in 0.785621037 seconds.
```
Most of these are due to unused or uninitialized variables. This patch
fixes all warnings by fixing offending code.
Allow developers to use Stripe test data when stubbing responses
locally. This should help mitigate the risk of API drift with stubbed
responses.
* Move response helpers to their own file
