Change commands in the Getting Started guide to use scripts in bin/ [ci skip]

[ci skip]

This is a better test for 51660f01. It is testing that the SQL is the
same before and after the previously leaky scope is called. Before if
`hotel.drink_designers` was called first then `hotel.recipes` would
incorrectly get the scope applied. We want to be sure that the
polymorphic hm:t association is not leaking into or affecting the
SQL for the hm:t association on `Hotel`.

The reason I couldn't do this before was because there was an issue with
the SQL getting cached and wanted to resolve that later and then fix the
test to be better. Because of the caching, this test requires that
`Hotel.reflect_on_association(:recipes).clear_association_scope_cache`
be called after the first call to `hotel.recipes` to clear the
assocation scope chain and not interfere with the rest of the test.

In the tests if I were to call `post.categorizations.to_a` and then later call
`post.categorizations.to_a` expecting to have different results the 2 queries
would be the same because of the caching involved in
`@association_scope_cache`. The chain gets cached and the queries will
be the same even if they are not supposed to be (i.e. testing an order
dependent scoping issue).

I found this issue because I was working on a bug with cached scoped
in hm:t and hm:t polymorphic relationships but `capture_sql` was
outputting the wrong SQL to write a good test.

Remove gem check in guides/rails_guides.rb

Conflicts:
	guides/rails_guides.rb

This logic was just doing duplicated work, since the button_to helper
relies on tag/content_tag to generate the button html, which already
handles all boolean attributes it knows about.

The code dates back to 2005: 43c470fa.

Reuse the CollectionAssociation#reader proxy cache if the foreign key is present from the start.

Conflicts:
	activerecord/CHANGELOG.md

Make example code consistent for better understanding. [ci skip]

Update old link in pessimistic.rb comments [ci skip]

Update link in comments to point to latest MySQL production version documentation. See here for reference: http://dev.mysql.com/doc/refman/5.0/en/choosing-version.html

Fix NullRelation.update_all and .exists? signature to match the same on Relation

Fix wrong model name for 'Articles', It should be 'Article' [ci skip]

- Also changed 'a' to 'an' for 'Article' word.

Compare content_type with Mime::XML instead of regexp

Skip the `:race_condition_ttl` branch if the option is 0 or nil.

Add config.active_record.dump_schemas.

Fixes db:structure:dump when using schema_search_path and PostgreSQL
extensions.

Closes #17157.

Drop `references_eager_loaded_tables?` test from `has_include?`

It is redundant with tests in `eager_loading?`, but for the difference
between `includes_values.present?` and `includes_values.any?`, which
is a difference without a distinction because `false` has no meaning
for `includes`.

Fix deprecation warning in rails_info_controller tests

Use keyword arguments in request methods

Remove unused variable in activerecord reflection_test.

[ci skip] reflection doc fix about hierarchy

Materialize subqueries by adding `DISTINCT` to suport MySQL 5.7.6 and later

Renaming transactional fixtures to transactional tests

I’m renaming all instances of `use_transcational_fixtures` to
`use_transactional_tests` and “transactional fixtures” to
“transactional tests”.

I’m deprecating `use_transactional_fixtures=`. So anyone who is
explicitly setting this will get a warning telling them to use
`use_transactional_tests=` instead.

I’m maintaining backwards compatibility—both forms will work.
`use_transactional_tests` will check to see if
`use_transactional_fixtures` is set and use that, otherwise it will use
itself. But because `use_transactional_tests` is a class attribute
(created with `class_attribute`) this requires a little bit of hoop
jumping. The writer method that `class_attribute` generates defines a
new reader method that return the value being set. Which means we can’t
set the default of `true` using `use_transactional_tests=` as was done
previously because that won’t take into account anyone using
`use_transactional_fixtures`. Instead I defined the reader method
manually and it checks `use_transactional_fixtures`. If it was set then
it should be used, otherwise it should return the default, which is
`true`. If someone uses `use_transactional_tests=` then it will
overwrite the backwards-compatible method with whatever they set.

Move Adapter to private constant

to support MySQL 5.7.6 `optimizer_switch='derived_merge=on'`

Adds more clarity on how to use custom rake tasks with arguments passed to it [ci skip]

Regexp is broken for both content types including charsets and for
integration tests, where the content_type is a Mime::Type and not String

When a new record has the necessary information prior to save, we can
avoid busting the cache.

We could simply clear the @proxy on #reset or #reset_scope, but that
would clear the cache more often than necessary.

[skip ci] Fix typos in guides

[skip ci] Fix typo in actionmailer documentation