Unintended dependency to active_record

[andreaseger]

Expected behavior vs actual behavior

I expect to be able to use AMS without active_record. What I'm seeing is that to_json won't serialize the serializer adapter instance correctly if I don't explicitly call as_json before hand. If I load active_record and establish a database connection a simple call to to_json will work as expected

Steps to reproduce

Please have a look at this gist
https://gist.github.com/andreaseger/84edad45b690b142c401a170b742aafb

Environment

ActiveModelSerializers Version (commit ref if not on tag): latest master (d30aa4c)

Output of ruby -e "puts RUBY_DESCRIPTION": ruby 2.2.4p230 (2015-12-16 revision 53155) [x86_64-linux]

Additonal helpful information

Although I originally found this dependency issue with active_record in one of our apps @groyoh noticed that requiring active_support/json is enough to fix the behavior of to_json