Clergyman's

for the service in spec/service_spec.rb, you add another describe block:
— Paul Dix

You create a file called user.rb in the /models directory:
— Paul Dix

For invalid user name and password combinations, the service should return a 400 HTTP status code, which means that the server received a “bad request.” The service could also use the 401 (“unauthorized”) response code, but that code specifies that authentication credentials need to be in the request header, which is not quite what is required.
— Paul Dix

However, for the purposes of migrating existing Rails applications to services, the shared database approach may be necessary in the early stages.
— Paul Dix