Method .strip_heredoc is defined in
active_support/core_ext/string/strip.rb so we need to require it.

[fixes #16677]

[ActiveJob] TestCase

We're seeing too many failures to believe otherwise.

This reverts commits bc116a55,
cbde413d,
bf0a6793, and
2440933f.

ActiveJob: Implemented enqueue_at for QueueClassic

[ci skip] Fix a typo in the doc of MessageDelivery

Do not swallow exception on NameError within constant.

Now we keep only the common code and move the specific code to the gems

Fixes https://github.com/rails/rails/issues/9933.

use self instead of #read_attribute

Fix for configuring rails guide [ci skip]

`ActiveSupport::Logger` has no concept like auto flushing since it has no userspace buffering.
It's a remnant of `ActiveSupport::BufferedLogger` epoch which was since removed from rails.

Allow polymorphic routes with nil when a route can still be drawn

Clarify that /console is an optional feature

(/console is not mounted by default with web-console 2.0.)

Suppose you have two resources routed in the following manner:

```ruby
resources :blogs do
  resources :posts
end

resources :posts
```

When using polymorphic resource routing like `url_for([@blog, @post])`, and `@blog` is `nil` Rails should still try to match the route to the top-level posts resource.

Fixes #16754

[ActionMailer] Rename test/test_test to test/test_case_test

[ci skip] add line about text layout

Sets the connection collation to the database collation configured
in database.yml. Otherwise, `SET NAMES utf8mb4` will use the default
collation for that charset (utf8mb4_general_ci) when you may have chosen
a different collation, like utf8mb4_unicode_ci.

This only applies to literal string comparisons, not column values, so
it is unlikely to affect you.

so this assertion causes random test fail

When we are loading a component and we want to know its version, we are
actually not speaking about the constant but the library itself.

[ci skip]

[Godfrey Chan & Xavier Noria]

Use system /tmp for temp files when testing actionpack

This was removed by mistake in 5e51bdda