- 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
The reason some projects have both is so that some spec files can be
run in isolation, without the rails stuff. In practice, I don't find
myself ever doing this. So, the complexity of two files is unnecessary.