RoutingAssertions. [ci skip]

after views. [ci skip]

 Update CHANGELOG entry for #18070 [ci skip]

functional testing section and implement :show, :destroy, and :update tests.

[ci skip]

 - Improved wording of CHANGELOG entry for https://github.com/arthurnn/rails/commit/5acd24bbeae0e9e5e81e87b5929e17f35527b2ea.

Ensures that primary_key method will return nil when multi-pk

in the Action Dispatch Integration module. [ci skip]

When table has a composite primary key, the `primary_key` method for
sqlite3 and postgresql was only returning the first field of the key.

Ensures that it will return nil instead, as AR dont support composite pks.

Use more semantic method to authenticate password in SecurePassword

 Fix description for application_name method - change simple to simply [ci skip]

 [ci skip]

 Better docs for AV::RecordIdentifier [ci skip]

Remove single space response body for head request

- The single space response was added due to a bug in safari
  in https://github.com/rails/rails/commit/cb0f8fda9652c4d24d04693bdb82cecd3b067e5c
  and
  https://github.com/rails/rails/commit/807df4fcf021fc4d15972aa1c17ba7398d43ab0d.
- This was removed from the `render nothing: true` in
  https://github.com/rails/rails/pull/14883.
- Removing it from response of :head also. As :head is more obvious
  alternative to call `render nothing:
  true`(http://guides.rubyonrails.org/layouts_and_rendering.html#using-head-to-build-header-only-responses),
  removing it from head method also.
- Closes #18253.

Fix form_for to work with objects that implement to_model

Closes #7247.

Conflicts:
	activerecord/CHANGELOG.md
	activerecord/test/models/owner.rb

Given the following templates:

    mailer/demo.html.erb
    mailer/demo.en.html.erb
    mailer/demo.pt.html.erb

Before this change for a locale that doesn't have its related file
the `mailer/demo.html.erb` will
be rendered even if `en` is the default locale.

Now `mailer/demo.en.html.erb` has precedence over the file without
 locale.

Also, it is possible to give a fallback.

    mailer/demo.pt.html.erb
    mailer/demo.pt-BR.html.erb

So if the locale is `pt-PT`, `mailer/demo.pt.html.erb` will be
 rendered given the right I18n fallback configuration.

Fixes #11884.

It makes more sense here, rather than after explaining all of the testing
facilities of Rails. [ci skip]

Previously, if you tried to use form_for with a presenter object
that implements to_model, it would crash in
action_dispatch/routing/polymorphic_routes.rb when asking the presenter
whether it is .persisted?

Now, we always ask .persisted? of the to_model object instead.

This seems to been an issue since 1606fc9dSigned-off-by: NEugenia Dellapenna <eugenia.dellapenna@gmail.com>

82b75eda

Also explain how Rails inherits capabilities from Minitest. Test classes should
be roughly the same based on this information, we can address them at a high
level when introducing the first test case. [ci skip]

assertions are introduced. [ci skip]

existing example. [ci skip]

My reasoning is that this is probably too much information for the complete
Rails testing guide, as we're trying to cover testing all aspects of the
framework.

before this PR IDENTIFIER_ERROR_MESSAGE could lead to misunderstand the convention of partial name.
Added OPTION_AS_ERROR_MESSAGE for unvalid charter in as option.

Add doc for `:touch` option of AR::Base#save

ActiveRecord::Base `save` and `save!` take an option boolean
`:touch` parameter since #18225 (stems from #18202).

This commit document that parameter.

[ci skip]