Eliminate minitest warnings

https://github.com/seattlerb/minitest/commit/9a57c520ceac76abfe6105866f8548a94eb357b6#L15R8
partition the where values so we can access the removed ones
In batches test @total was assigned but not used. Use it in tests instead of Post.count
Merge pull request #10702 from divineforest/use-total-in-batches-test

Use @total variable created in the setup of batches tests instead of counting again.
the rake task `db:test:prepare` needs to load the configuration

Without loading the configuration the task will not perform any work.
Merge pull request #10711 from senny/10660_rake_db_test_prepare_needs_config

the rake task `db:test:prepare` needs to load the configuration
Extract AR::Core#inspect and AR::Core.inspect's test code from base_test.rb

The methods got moved to core.rb in commit
b2c9ce341a1c907041f55461aefebb0321280cb5, but the tests never did.
Extract AR::AttributeMethods#attribute_for_inspect's test code out from base_test.rb

The method itself got extracted out from ActiveRecored::Base in commit
ceb33f84933639d3b61aac62e5e71fd087ab65ed, but the test code never did.
push partion logic down and initialization logic up
push partitioning up so bind elimination can get the removed wheres
remove bind values for where clauses that were removed
avoid creating a set if no where values are removed
Merge branch 'bindwhere'

* bindwhere:
  avoid creating a set if no where values are removed
  remove bind values for where clauses that were removed
  push partitioning up so bind elimination can get the removed wheres
  push partion logic down and initialization logic up
  partition the where values so we can access the removed ones
use drop rather than calculate the array length
fold the collection rather than multiple assigments
just set the default argument, a nil parent should be an error
reverse comparison because of strange AS behavior

http://tenderlovemaking.com/2013/05/21/one-danger-of-freedom-patches.html
Extract AR::Persistence#becomes's test code out from base_test.rb

The method got extracted out from AR::Base in commit
d916c62cfc7c59ab6411407a05b946d3dd7535e9, but the tests never did.
Add ActiveModel requirement to application.rb

Currently, ActiveModel is only loaded by ActiveRecord. If you skip ActiveRecord, ActiveModel will not be required (or even autoloaded) and including `ActiveModel::Model` into a plain Ruby class will raise `NameError`.

To reproduce this:

- create a new app with `rails new my_app -O`
- create a Ruby class that includes `ActiveModel::Model` in `app/models`
- load up a Rails console and try to do anything with the class :-)

Since ActionPack relies so heavily on the ActiveModel API, this should probably be considered a dependency of the app. Another possibility would be to make it a dependency of ActionController.
Merge pull request #10722 from jgaskins/patch-1

Add ActiveModel requirement to application.rb