`default_middleware_stack` seems to kick off the `on_load` calls that
may mutate the middleware stack.  We have to call that method before
merging middleware stacks, otherwise the middleware stacks get mutated
*after* the app middleware stack is built.

We shouldn't merge the app middleware in to the config middleware for
engines.

Eliminate overlapping `app/assets` load path

* Move `app/assets/manifest.js` to `app/assets/config/manifest.js`.
  Avoid the suggestion that you can/should deep-link `stylesheets/foo`.
* Pull in all toplevel stylesheets and JavaScripts, not just
  `application.js` and `.css`. Demonstrate how to use `link_directory`
  with a specified `.js`/`.css` type.
* Fix RAILS_ENV handling in assets tests.
* Shush warnings spam from third-party libs that distract from tests.

Allocating a new middleware proxy in each application configuration and
then merging the app specific config with the global config when the app
is built.

Improve readability of docs by using code tag [ci skip]

Fix documentation for has_many dependant options.

* A `has_many` dependant association accepts `[:destroy, :delete_all, :nullify,
:restrict_with_error, :restrict_with_exception]` as options.
Currently the documentation references `delete` instead of `delete_all`
* Adds documentation for other options

Add fail fast reporting to test runner.

Passing `--fail-fast` to the test runner will now abort the test run
on the first failure. The run continues on any unexpected errors.

Fix - Prevent adding of `data-disable-with` option twice in html.

Remove TestRouter#add_routes

Now, we use the mapper to build the routing table

related to https://github.com/rails/rails/commit/703275ba70efbefb3358052b6ba750443eff1a28

Fix names of test cases

Update docs for `formatted_offset`

Output of `formatted_offset` is depends on input so it’s not always in +HH:MM format. Possible outputs are “+5:30”, “+530” or provided alternate UTC string [ci skip]

the caller of `handle_conditional_get!` checks the committed state of
the response, so we don't need to in the subclass.

I'm looking to move towards a tree-like structure for dirty checking
that involves an attribute holding onto the attribute that it was
created from. This means that `changed?` can be fully encapsulated on
that object. Since the objects are immutable, in `changes_applied`, we
can simply perform a shallow dup, instead of a deep one.

I'm not sure if that will actually end up in a performance boost, but
I'd like to semantically separate these concepts regardless

The external uses of this method have been removed, and I'd like to
internally re-use that name, as I'm planning to encapsulate `changed?`
into the attribute object itself.

no more class methods for JoinDependency [ci skip]

`ActiveRecord::Associations::JoinDependency` now it’s own class` and `ActiveRecord::Associations::ThroughAssociationScope` doesn’t exists

Any failures or errors will be reported inline during the run by default.
Skipped tests will be reported if run in verbose mode.

Any result is output with failure messages and a rerun snippet for that test.

Rerun snippets won't be output after a run, unless `--defer-output` is passed.

Updated docs for transform_keys & transform_values

We're calling this function on an empty hash as part of copying the
attribute set during dirty checking initialization. The new structure
caused a performance regression on loading records from the database.
This causes `User.all.to_a` to perform about 10% faster w/ 10k records.

Calculating -------------------------------------
   User.all - master     9.000  i/100ms
   User.all - sg-fix-ar-regression
                         8.000  i/100ms
-------------------------------------------------
   User.all - master     81.236  (± 7.4%) i/s -    405.000
   User.all - sg-fix-ar-regression
                         89.716  (± 7.8%) i/s -    448.000

Make fuzzy sentence more clear

[ci skip]

check if @rake_patterns is defined

This removes the following warning.
```
railties/lib/rails/test_unit/minitest_plugin.rb:45: warning: instance variable @rake_patterns not initialize
```

Fix minor docs [ci skip]

Fix `ActiveRecord::RecordNotFound` error message with custom primary …

[ci skip] Update docs of `AR::Sanitization`

[ci skip] Fix which method `FormHelper#date_field` try to call

minor doc fix [ci skip]