JsonGem and JsonPure adapters should work with the yajl-ruby compatible ::JSON implementations.

yajl-ruby's "yajl/json_gem" overwrites ::JSON implementation in a "compatible" way, but the options expected are different.  yajl-ruby expects :symbolize_keys, while the json gem expects :symbolize_names. 

yajl-ruby has patched this issue in HEAD, for v2 of the gem which is unreleased, but it doesn't appear they will backport to v1.1.  v1.1.0 was released 2 years ago, so I'm not certain when v2 will be released...

https://github.com/brianmario/yajl-ruby/issues/94
https://github.com/brianmario/yajl-ruby/pull/105

To explain the impact, I just hit this issue last week and here are some other people who have run into it as well: https://github.com/sferik/twitter/issues/317


Note: I read the contribution guidelines and tried todo `open coverage/index.html`, but i didn't have a coverage directory - even after running the rspec tests.  Not sure if this is a requirement anymore or not.