Add sensible defaults to active record objects

[searls]

• By default, (recursively?) compare attributes, excluding id, created_at, and updated_at.
• initially implement with a devdep on AR, but replace it with a minimal fake once we're done to save on build time.

[searls]

Some thoughts: AR's default == behavior makes for a really bad out-of-the-box experience with Suture

I am truly happy to release a Suture 1.0.0 without any AR-specific affordances, but for the fact that by default users will get confusing false positives if they pass in or return AR objects to and from seams.

By default, AR will consider two already-persisted objects equivalent if their IDs match. This is definitely a problem with Suture'a default comparator, because drastically-mutated AR objects will be seen as "passing" in Suture.verify tests and as comparable in staging (e.g. call_both mode).

Since some woefully high percentage of legacy Ruby classes extend from AR::Base, this is a terrible out-of-the-box experience because it looks like it's passing immediately, the user must recognize it is not, and then figure out the Custom Comparator API to look at just the properties they care about.

This is unacceptably bad UX IMO.

[searls]

My inclination at this point is to do a few things:

• Add to the default comparator a check for defined?(ActiveRecord::Base) and if both objects are AR Base, enter a branch to compare them
• By default, compare the two objects' attribute hashes
• Expose a config property like :ignore_active_record_attributes which defaults to created_at and updated_at.
• I have no idea how to handle associations for this purpose, though.

As an aside, I'm saying "ActiveRecord" here since attributes is defined in AR and not on ActiveModel. In practice I'm more interested in solving for the vast majority of cases rather than trying to build-in a super-smart comparator to serve everyone.