It's better to use Ruby methods when possible over methods defined by
Active Support because then it does not need to rely on any
dependencies.

Code was moved into the `assign` method.

`head` method works similar to `render` method with `:nothing` option

spelling fix [ci skip]

example to be consistent [ci skip]

grammatical fix

typo fixes [ci skip]

Stems from https://github.com/rails/rails/pull/20105#issuecomment-100900939
where @senny said:

> From my point of view, all the docs (guides, API) are version bound.
> They should describe that version and continue to be available when newer versions are released.
> The cross referencing can be done by the interested user.

This moves `TemplateAssertions` out of the `test_case.rb` file and into
it's own `template_assertions` file. It still inherits from
`ActionController`.`

This is in preparation for combining the code for Integration tests and
Controller tests. This will need to be it's own file to be added to the
`requires` for Integration tests. This does not currently change ANY
behavior, just moving it for access later on.

Digest allowed the messages.
Add the same feature to basic and token

`*args` is not required here and should be avoided when not necessary
because `*args` are slower than `args` and create unnecessary array
allocations.

 - Changed Javascript to JavaScript.
 - Added full-stop which was missing, also wrapped the sentence to 80 chars.
 - Changed proc to Proc and oauth to OAuth.

[ci skip]

specifically are checked for CSRF, when dealing with the browser.

[ci skip]

This reverts commit d2156203, reversing
changes made to bbbbfe1a.

After merging #19377 ActionPack tests were missing a require for
`ActiveSupport::LogSubscriber::TestHelper` and change didn't take
into account that logger could be nil. Added the require and only log to
info if logger exists.

This wasn't caught earlier because these tests only run after a merge.

https://github.com/ruby/ruby/pull/579 - there is a new optimization
since ruby 2.2

Previously regexp patterns were faster (since a string was converted to
regexp underneath anyway). But now string patterns are faster and
better reflect the purpose.

  Benchmark.ips do |bm|
    bm.report('regexp') { 'this is ::a random string'.gsub(/::/, '/') }
    bm.report('string') { 'this is ::a random string'.gsub('::', '/') }
    bm.compare!
  end
  # string: 753724.4 i/s
  # regexp: 501443.1 i/s - 1.50x slower

The current implementation of ActionController::Parameters.const_missing
returns `ActionController::Parameters.always_permitted_parameters` even
if its `super` returns a constant without raising error. This prevents its
subclass in a autoloading module/class from taking advantage of
autoloading constants.

    class SomeParameters < ActionController::Parameters
      def do_something
        DefinedSomewhere.do_something
      end
    end

In the code above, `DefinedSomewhere` is to be autoloaded with
`Module.const_missing` but `ActionController::Parameters.const_missing`
returns `always_permitted_parameters` instead of the autoloaded
constant.

This pull request fixes the issue respecting `const_missing`'s `super`.

Closes #18933.

It was returning false in normal circumstances.
This broke the `head :ok and return if` construct.
Add appropriate test.

As of the upgrade to Rack 1.5, request.session_options[:id] is no
longer populated. Reflect this change in the tests by using
request.session.id instead.

Related change in Rack:
https://github.com/rack/rack/commit/83a270d6

 - The request needs to be instance of ActionDispatch::Request or an
   object that responds to host, optional_port, protocol and
   symbolized_path_parameter.
 - This documentation was correctly added in
   https://github.com/rails/rails/commit/e3b3f416b57f5642ea25078485f7e9394ad04526
   but was changed to
   https://github.com/rails/rails/commit/e1ceae576e3911f3e6708b5d19a0e3ef63769eb7.
 - Fixes #16160.