Services isolated on business logic can share data sources with other systems.
However, for the purposes of migrating existing Rails applications to services, the shared database approach may be necessary in the early stages.
You create a file called user.rb in the /models directory:
for the service in spec/service_spec.rb, you add another describe block:
Many programmers would prefer to mock in their client library specs, but doing so could result in the service and client passing all specs with hidden failures.