assert_payload tests can become false positives on empty attributes payload and nil json_item

[Startouf]

I have special payload/serialized result in my app made almost entirely of relationships and no attributes (a conversation = list of messages + references to senders, etc.)

Therefore, my test payload declaration was empty.

In my test, the payload assertion was passing although the return from the controller was nil / the test should have failed

In a nutshell :

# spec/payloads/messaging/conversation.rb
JsonapiSpecHelpers::Payload.register(:'messaging/conversation') do
# empty, only relationships
end

# spec/requests/messaging/conversations_controller.rb
...
json_item = {"id"=>nil, "jsonapi_type"=>nil}
assert_payload(:'messaging/conversation', conversation, json_item)
# Would pass !

[richmolj]

Yeah, this is a good point. Currently we validate all the payload keys, but not id/type. We should add that. I can get to that within a week or so.