In order to use early hints, need to use Puma 3.11.0 or higher.
So, I think that should specify that version in newly generated applications.

Ref: https://github.com/puma/puma/commit/f6f3892f4d82638fb7a2a57d993641b1486ee88a

We generate master key on `rails new`.
Therefore, if do not add master key to `.gitginore` on `rails new`as
well, there is a possibility that the master key will be committed
accidentally.

These were added in #30101, after #31084 it became redundant.

In order to execute the `rails` command, need to run bundle install in
advance.
Therefore, if skipped bundle install, `rails` command may fail and
should not do it.

Omit `rails activestorage:install` for jdbcmysql, jdbc and shebang tests

AppGeneratorTest#test_config_jdbcmysql_database

  rails aborted!
  LoadError: Could not load 'active_record/connection_adapters/mysql_adapter'.
  Make sure that the adapter in config/database.yml is valid.
  If you use an adapter other than 'mysql2', 'postgresql' or 'sqlite3' add
  the necessary adapter gem to the Gemfile.
  (compressed)
  bin/rails:4:in `<main>'
  Tasks: TOP => activestorage:install => environment
  (See full trace by running task with --trace)

AppGeneratorTest#test_config_jdbc_database

  rails aborted!
  LoadError: Could not load 'active_record/connection_adapters/jdbc_adapter'.
  Make sure that the adapter in config/database.yml is valid.
  If you use an adapter other than 'mysql2', 'postgresql' or 'sqlite3' add
  the necessary adapter gem to the Gemfile.
  (compressed)
  bin/rails:4:in `<main>'
  Tasks: TOP => activestorage:install => environment
  (See full trace by running task with --trace)

AppGeneratorTest#test_shebang_is_added_to_rails_file

  /home/ubuntu/.rbenv/versions/2.4.1/bin/ruby: no Ruby script found in input (LoadError)

Prevent PendingMigrationError in tests

 * Run `bin/rails db:migrate RAILS_ENV=test` in test_cases before start tests to prevent PendingMigrationError
 * FileUtils.rm_r("db/migrate")
 * --skip-active-storage

Fix failed tests in `railties/test/railties/engine_test.rb`

Related to #30111

Imporve `SharedGeneratorTests#test_default_frameworks_are_required_when_others_are_removed`

 - Explicitly skip active_storage
 - Ensure that skipped frameworks are commented
 - Ensure that default frameworks are not commented

Fix error `Errno::ENOSPC: No space left on device - sendfile`

Since `rails new` runs `rails active_storage:install`
that boots an app.

Since adding Bootsnap 0312a5c6
during booting an app, it creates the cache:

   264K    tmp/cache/bootsnap-load-path-cache
   27M     tmp/cache/bootsnap-compile-cache

* teardown_app must remove app

Closes #30102

Revert part 787fe90d

--skip-active-storage pass throughs `rails plugin new`

Add changelog entry about default initialization of Active Storage

If specify the `quiet` option, expect that no status will be shown.
However, some process show status. This suppresses all status output.

* WIP: Add credentials using a generic EncryptedConfiguration class

This is sketch code so far.

* Flesh out EncryptedConfiguration and test it

* Better name

* Add command and generator for credentials

* Use the Pathnames

* Extract EncryptedFile from EncryptedConfiguration and add serializers

* Test EncryptedFile

* Extract serializer validation

* Stress the point about losing comments

* Allow encrypted configuration to be read without parsing for display

* Use credentials by default and base them on the master key

* Derive secret_key_base in test/dev, source it from credentials in other envs

And document the usage.

* Document the new credentials setup

* Stop generating the secrets.yml file now that we have credentials

* Document what we should have instead

Still need to make it happen, tho.

* [ci skip] Keep wording to `key base`; prefer defaults.

Usually we say we change defaults, not "spec" out a release.

Can't use backticks in our sdoc generated documentation either.

* Abstract away OpenSSL; prefer MessageEncryptor.

* Spare needless new when raising.

* Encrypted file test shouldn't depend on subclass.

* [ci skip] Some woordings.

* Ditch serializer future coding.

* I said flip it. Flip it good.

* [ci skip] Move require_master_key to the real production.rb.

* Add require_master_key to abort the boot process.

In case the master key is required in a certain environment
we should inspect that the key is there and abort if it isn't.

* Print missing key message and exit immediately.

Spares us a lengthy backtrace and prevents further execution.

I've verified the behavior in a test app, but couldn't figure the
test out as loading the app just exits immediately with:

```
/Users/kasperhansen/Documents/code/rails/activesupport/lib/active_support/testing/isolation.rb:23:in `load': marshal data too short (ArgumentError)
	from /Users/kasperhansen/Documents/code/rails/activesupport/lib/active_support/testing/isolation.rb:23:in `run'
	from /Users/kasperhansen/.rbenv/versions/2.4.1/lib/ruby/gems/2.4.0/gems/minitest-5.10.2/lib/minitest.rb:830:in `run_one_method'
	from /Users/kasperhansen/.rbenv/versions/2.4.1/lib/ruby/gems/2.4.0/gems/minitest-5.10.2/lib/minitest/parallel.rb:32:in `block (2 levels) in start'
```

It's likely we need to capture and prevent the exit somehow.
Kernel.stub(:exit) didn't work. Leaving it for tomorrow.

* Fix require_master_key config test.

Loading the app would trigger the `exit 1` per require_master_key's
semantics, which then aborted the test.

Fork and wait for the child process to finish, then inspect the
exit status.

Also check we aborted because of a missing master key, so something
else didn't just abort the boot.

Much <3 to @tenderlove for the tip.

* Support reading/writing configs via methods.

* Skip needless deep symbolizing.

* Remove save; test config reader elsewhere.

* Move secret_key_base check to when we're reading it.

Otherwise we'll abort too soon since we don't assign the secret_key_base
to secrets anymore.

* Add missing string literal comments; require unneeded yaml require.

* ya ya ya, rubocop.

* Add master_key/credentials after bundle.

Then we can reuse the existing message on `rails new bc4`.

It'll look like:

```
Using web-console 3.5.1 from https://github.com/rails/web-console.git (at master@ce985eb)
Using rails 5.2.0.alpha from source at `/Users/kasperhansen/Documents/code/rails`
Using sass-rails 5.0.6
Bundle complete! 16 Gemfile dependencies, 72 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.
Adding config/master.key to store the master encryption key: 97070158c44b4675b876373a6bc9d5a0

Save this in a password manager your team can access.

If you lose the key, no one, including you, can access anything encrypted with it.

      create  config/master.key
```

And that'll be executed even if `--skip-bundle` was passed.

* Ensure test app has secret_key_base.

* Assign secret_key_base to app or omit.

* Merge noise

* Split options for dynamic delegation into its own method and use deep symbols to make it work

* Update error to point to credentials instead

* Appease Rubocop

* Validate secret_key_base when reading it.

Instead of relying on the validation in key_generator move that into
secret_key_base itself.

* Fix generator and secrets test.

Manually add config.read_encrypted_secrets since it's not there by default
anymore.

Move mentions of config/secrets.yml to config/credentials.yml.enc.

* Remove files I have no idea how they got here.

* [ci skip] swap secrets for credentials.

* [ci skip] And now, changelogs are coming.

And enable `context_dependent` of Style/BracesAroundHashParameters cop.

Add SharedGeneratorTests#application_path
This method will help to DRY in files app_generator_test.rb, plugin_generator_test.rb

It can't use JavaScript in api mode.
Action cable should be disabled by default.

Improve app generator tests.

Ensure that generation `config/application.rb` is correct.

Ensure that generation `config/application.rb` is correct.

This reverts commit a8f59044.

See discussion on https://github.com/rails/rails/pull/30016.

This reverts commit fd7f978a.

The fallback javascript engine on Windows is Windows Script Host (JScript).
However this engine isn't able to process the default assets, because it supports
ES3 only but the coffeescript compiler requires ES5.

Fixes #30014

Currently, `app:update` generates all contents regardless of the
component using in application.

For example, even if not using Action Cable, `app:update` will generate
a contents related to Action Cable. This is a little inconvenient.
This PR checks the existence of the component and does not generate
unnecessary contents.
Can not check all options in this way. However, it will be able to
prevent the generation of unnecessary files.

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

Allows users to not have remote forms by default, since there's
more JS harness, e.g. bundling rails-ujs, otherwise.

Also don't skip creating defaults file anymore. Sprockets isn't the only new config.

The "-j" option was added 5 years ago (https://github.com/rails/rails/commit/d9c39c3a)
when we wanted to support prototype-rails and jquery-rails.
Prototype is not as popular and jQuery is not a requirement anymore.
Still the "-j" option can be used to install *any* gem that ends in "-rails".

This "might" open security issues and does not bring great benefits anymore.

If you know which "-rails"-ending gem you want to install, you can manually
add it to the Gemfile just like any other gem.

This is necessary only when updating to Rails 5.0, it is not necessary
for updating to 5.1.

Related #24243

It can not check correctly with `defined?`

```ruby
irb(main):001:0> Rails.application.config.active_record
=> {:maintain_test_schema=>true, :belongs_to_required_by_default=>true}
irb(main):002:0> defined?(Rails.application.config.active_record)
=> nil
```

Follow up to #28469

Instead of forcing new applications to carry an initializer that just
switches things to what their default "should" be, we can handle it
internally.

The initializer is then only used by upgraders: it shows what the new
default would be (commented out), while their upgraded application
continues to operate as it did before.

Under this model, a multiply-upgraded application could accumulate
several new_framework_defaults_*.rb files, for each release series it
has traversed. A given release series only needs to generate the latest,
though, because we don't support `rails app:upgrade` while skipping
releases.

`rails:update` was changed to `app:update` in 6fb31638.
Therefore, I think that it is better that the test name is also `app_update`.