In a test app we observed that the query cache was not enabled on the
first request. This was because the query cache hooks are installed on
load and active record is loaded in the middle of the first request.

If we remove the `on_load` from the railtie the query cache hooks will
be installed before the first request, allowing the cache to be enabled
on that first request.

This is ok because query cache doesn't load anything else, only itself
so we're not eager loading all of active record before the first
request, just the query cache hooks.

[Eileen M. Uchitelle & Matthew Draper]

`to_prepare` callbacks are run during initialization; using one here
meant that `ActiveStorage::Blob` would be loaded when the app boots,
which would in turn load `ActiveRecord::Base`.

By using a lazy load hook to configure `ActiveStorage::Blob` instead,
we can avoid loading `ActiveRecord::Base` unnecessarily.

See #30520

This reverts commit 3420a145, reversing
changes made to afb66a5a.

Style/SpaceBeforeBlockBraces
Style/SpaceInsideBlockBraces
Style/SpaceInsideHashLiteralBraces

Fix all violations in the repository.

The current code base is not uniform. After some discussion,
we have chosen to go with double quotes by default.

- The `boot_rails` method from abstract_unit.rb is empty after 2abcdfd9.
- So let's remove it and its usage.

This PR introduces a key/value type store to Active Record that can be used for storing internal values. It is an alternative implementation to #21237 cc @sgrif @matthewd.

It is possible to run your tests against your production database by accident right now. While infrequently, but as an anecdotal data point, Heroku receives a non-trivial number of requests for a database restore due to this happening. In these cases the loss can be large.

To prevent against running tests against production we can store the "environment" version that was used when migrating the database in a new internal table. Before executing tests we can see if the database is a listed in `protected_environments` and abort. There is a manual escape valve to force this check from happening with environment variable `DISABLE_DATABASE_ENVIRONMENT_CHECK=1`.

Apart from specific versioning support, our tests should focus on the
behaviour of whatever version they're accompanying, regardless of when
they were written.

Application code should *not* do this.

LoadingTest#test_does_not_reload_constants_on_development_if_custom_file_watcher_always_returns_false in railties/test/application/loading_test.rb is failing with: `NoMethodError: undefined method 'execute' for #<#<Class:0x00000002465a30>:0x00000001f79698>`

The test creates an anonymous class to be used as a custom file watcher using `config.file_watcher=`. Per the Rails guides for Configuring, the class set to `config.file_watcher` “Must conform to ActiveSupport::FileUpdateChecker API”. Per the docs for ActiveSupport::FileUpdateChecker, the API depends on four methods: #initialize, #updated?, #execute, and #execute_if_updated. The custom file watcher in the failing test only implements the first two methods.

This pull request adds #execute and #execute_if_updated to the custom file_watcher, conforming it to the ActiveSupport::FileUpdateChecker API, and passing the test.

Rails.application when drawing routes and creating other configurations
on the application.

Conflicts:
	railties/test/application/loading_test.rb

more agnostic Rails.application syntax. This means tests will be more
portable, and won't rely on the existence of a particular subclass.

In the current router DSL, using the +match+ DSL
method will match all verbs for the path to the
specified endpoint.

In the vast majority of cases, people are
currently using +match+ when they actually mean
+get+. This introduces security implications.

This commit disallows calling +match+ without
an HTTP verb constraint by default. To explicitly
match all verbs, this commit also adds a
:via => :all option to +match+.

Closes #5964

Changes:

* `Rails.initialized=` has been removed
* `Rails.initialized?` and `Rails.application.initialized?` are now
* delegating to `MyApp::Application.initialized?`

SchemaMigration model is loaded on rails initialization,
which means that it will not be cleaned on each request.

Clean up the cache before the request in case we are running in the reload_classes_only_on_change schema.

Add config.file_watcher so developers can provide their own watchers (for instance, hooking on fsevents).

This can be turned off by setting `config.reload_classes_only_on_change` to false.

Extensions like Active Record should add their respective files like db/schema.rb and db/structure.sql to `config.watchable_files` if they want their changes to affect classes reloading.

Thanks to https://github.com/paneq/active_reload and Pastorino for the inspiration. <3