Fix for ActiveRecord dirty attributes for rails 5.2

[madding]

Cause of bug:
rails/rails#33753 (comment)
You cannot call attribute_will_change! on something not registered with the attributes API -- There must be attribute :user_ids if you want that to be managed by Active Record.

For fixing this I added instantce variable where store changed attributes after save.

[hashicorp-cla]

All committers have signed the CLA.

[justincampbell]

Thanks for submitting! This seems to have a lot of changes unrelated to the fix for Rails 5.2. Could you rebase the PR with only the tests and implementation for the fix? I'm happy to review the other changes too in separate PRs, but minimizing the scope of this PR would increase my confidence in merging and releasing it.

[madding]

@justincampbell I left only the necessary changes

[madding]

I rebased branch

[justincampbell]

@madding Thanks for keeping this updated! I wasn't able to allocate time to get Rails 5.2 support into the 0.5.0 release, but I hope to find time to review this and get another release out soon. Thanks for your patience!

[dankozlowski]

Hey @justincampbell What's the ETA here? This merge is blocking use of the gem for us. Can I help?

[Valarissa]

#67 was merged. Do you feel like that PR handles all the issues put forth in this PR, or do you feel like something in that PR misses something in your PR @madding ? If it does, then may I close this PR? If it doesn't, would you be able to elaborate what?

Thanks in advance, and sorry for leaving this to languish for so long.

[madding]

@Valarissa I think you can close my PR. Yesterday was PRs birthday :)