Since Rails 5.0, belongs_to_required_by_default has been the official ActiveRecord default.
Add the configuration lines necessary to enable this default in both 5.0 and 5.1.
Add "optional: true" where necessary to fix spec failures caused by this change.
Add version-checking conditionals where necessary.
Update the Changelog appropriately.
- Convert serializers/mixin_json_test.rb to rspec
- Convert functional/thread_safety_test.rb to rspec
- Convert functional/controller_test.rb to rspec
- Move the dummy app from test to spec, delete test dir
Jared Beck