Since #30016 Rails generates `.ruby-version` file
in order to help Ruby version manager tools like `rbenv`, `rvm`
determine which Ruby version should be used for the current Rails
project.

Since #32649 Rails sets Ruby version to the file compatible with MRI/JRuby
by default.

Pull Request #31496 reports that `.ruby-version` doesn't match ruby version other
than stable version and recommends to use `ENV["RBENV_VERSION"]`, and
`ENV["rvm_ruby_string"]` in order to set correct Ruby version to the file
that `rbenv` or `rvm` can understand.
Also, there is another similar issue that reports the same case if use
JRuby https://github.com/jruby/jruby/issues/5144.

Closes #31496, https://github.com/jruby/jruby/issues/5144.

Execute `rails new myapp -S` and then upgrade the app by using the `app:update` task, `bin/rails c` results in `NoMethodError`.

```
$ bin/rails app:update

$ bin/rails c
Traceback (most recent call last):
    44: from bin/rails:4:in `<main>'
(snip)
     1: from /Users/tanimichi.tsukuru/ghq/github.com/moneyforward/moneyplus/config/initializers/assets.rb:4:in `<top (required)>'
/Users/tanimichi.tsukuru/ghq/github.com/moneyforward/moneyplus/vendor/bundle/ruby/2.5.0/gems/railties-5.2.0/lib/rails/railtie/configuration.rb:97:in `method_missing': undefined method `assets' for #<Rails::Application::Configuration:0x00007fcb8d3697e0> (NoMethodError)
Did you mean?  asset_host
```

`assert_directory("test/system")` may pass even if `assert_file("test/system/.keep")` fails.

We don't use `mini_magick` directly since #32471.

Rubocop auto-correct doesn't work well, so I fixed indentation manually.

This change may only apply to POSIX-compliant systems.

Previously:

    $ ls -l config/master.key
    -rw-r--r--   1 owner  group      32 Jan 1 00:00 master.key

Now:

    $ ls -l config/master.key
    -rw-------   1 owner  group      32 Jan 1 00:00 master.key

ImageProcessing gem is a wrapper around MiniMagick and ruby-vips, and
implements an interface for common image resizing and processing. This
is the canonical image processing gem recommended in [Shrine], and
that's where it developed from. The initial implementation was extracted
from Refile, which also implements on-the-fly transformations.

Some features that ImageProcessing gem adds on top of MiniMagick:

  * resizing macros
    - #resize_to_limit
    - #resize_to_fit
    - #resize_to_fill
    - #resize_and_pad
  * automatic orientation
  * automatic thumbnail sharpening
  * avoids the complex and inefficient MiniMagick::Image class
  * will use "magick" instead of "convert" on ImageMagick 7

However, the biggest feature of the ImageProcessing gem is that it has
an alternative implementation that uses libvips. Libvips is an
alternative to ImageMagick that can process images very rapidly (we've
seen up 10x faster than ImageMagick).

What's great is that the ImageProcessing gem provides the same interface
for both implementations. The macros are named the same, and the libvips
implementation does auto orientation and thumbnail sharpening as well;
only the operations/options specific to ImageMagick/libvips differ. The
integration provided by this PR should work for both implementations.

The plan is to introduce the ImageProcessing backend in Rails 6.0 as the
default backend and deprecate the MiniMagick backend, then in Rails 6.1
remove the MiniMagick backend.

Somehow `test_config_another_database` didn't fail on CI, but it will
fail locally.

https://travis-ci.org/rails/rails/jobs/356212950#L2474-L2482

```
% bundle exec ruby -w -Itest test/generators/app_generator_test.rb -n test_config_another_database
Run options: -n test_config_another_database --seed 7260

# Running:

F

Failure:
AppGeneratorTest#test_config_another_database [test/generators/app_generator_test.rb:417]:
Expected /^\s*gem\s+["']mysql2["'], '~> 0.4.4'$*/ to match "source 'https://rubygems.org'\ngit_source(:github) { |repo| \"https://github.com/\#{repo}.git\" }\n\nruby '2.5.0'\n\n# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'\ngem 'rails', '~> 6.0.0.alpha'\n# Use mysql as the database for Active Record\ngem 'mysql2', '>= 0.4.4', '< 0.6.0'\n# Use Puma as the app server\ngem 'puma', '~> 3.11'\n# Use SCSS for stylesheets\ngem 'sass-rails', '~> 5.0'\n# Use Uglifier as compressor for JavaScript assets\ngem 'uglifier', '>= 1.3.0'\n# See https://github.com/rails/execjs#readme for more supported runtimes\n# gem 'mini_racer', platforms: :ruby\n\n# Use CoffeeScript for .coffee assets and views\ngem 'coffee-rails', '~> 4.2'\n# Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks\ngem 'turbolinks', '~> 5'\n# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder\ngem 'jbuilder', '~> 2.5'\n# Use Redis adapter to run Action Cable in production\n# gem 'redis', '~> 4.0'\n# Use ActiveModel has_secure_password\n# gem 'bcrypt', '~> 3.1.7'\n\n# Use ActiveStorage variant\n# gem 'mini_magick', '~> 4.8'\n\n# Use Capistrano for deployment\n# gem 'capistrano-rails', group: :development\n\n# Reduces boot times through caching; required in config/boot.rb\ngem 'bootsnap', '>= 1.1.0', require: false\n\ngroup :development, :test do\n  # Call 'byebug' anywhere in the code to stop execution and get a debugger console\n  gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]\nend\n\ngroup :development do\n  # Access an interactive console on exception pages or by calling 'console' anywhere in the code.\n  gem 'web-console', '>= 3.3.0'\n  gem 'listen', '>= 3.0.5', '< 3.2'\n  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring\n  gem 'spring'\n  gem 'spring-watcher-listen', '~> 2.0.0'\nend\n\ngroup :test do\n  # Adds support for Capybara system testing and selenium driver\n  gem 'capybara', '>= 2.15', '< 4.0'\n  gem 'selenium-webdriver'\n  # Easy installation and use of chromedriver to run system tests with Chrome\n  gem 'chromedriver-helper'\nend\n\n# Windows does not include zoneinfo files, so bundle the tzinfo-data gem\ngem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]\n".

bin/rails test test/generators/app_generator_test.rb:411

Finished in 0.174681s, 5.7247 runs/s, 34.3483 assertions/s.
1 runs, 6 assertions, 1 failures, 0 errors, 0 skips
```

With the disabling of TLS 1.0 by most major websites, continuing to run
IE8 or lower becomes increasingly difficult so default to not enforcing
UTF-8 encoding as it's not relevant to other browsers.

Remove redundant assertions of an absence of `mini_magick` in `Gemfile`
since `bin/rails app:update` does not update Gemfile.
This assertions was added by 4a835aa3,
after reviewing of https://github.com/rails/rails/pull/32049 i realized
that assertions are redundant.

See https://github.com/rails/rails/pull/31957#issuecomment-364817423

The purpose of `--force` is not to have any prompt whether a file should
be kept or overwritten. In general, all existing files should be overwritten.
However, `config/master.key` is special because it is git-ignored, and
overwriting it will cause the app not to run (since there won't be a way
to decrypt the credentials).

As a result, it's probably better to keep the existing config/master.key.

Incompatible settings are included in the settings set by `load_defaults`.
So, I think that target version should be updated by a user when becomes
available, and should not be updated with `app:update`.

This is similar to #30700 which ensures the `--quiet` option of `rails new`
is respected by the `MasterKeyGenerator` (missing from #30067).

Before this commit, running `rails new app --force` would still prompt the
user what to do with the conflict in `config/master.key`:

```
              …
   identical  config/locales/en.yml
    conflict  config/master.key
Overwrite /Users/claudiob/Desktop/pizza/config/master.key? (enter "h" for help) [Ynaqdh]
```

After this commit, `config/master.key` is overwritten:

```
           …
identical  config/locales/en.yml
    force  config/master.key
   append  .gitignore
```

The newly added test generates an app and then generates it again with
`--force`. Without this commit, the test would just wait forever for user
input.

pg-1.0.0 is just released and most Gemfiles don't restrict
it's version. But the version is checked when connecting to
the database, which leads to the following error:

Gem::LoadError: can't activate pg (~> 0.18), already activated pg-1.0.0

See also this pg issue:
https://bitbucket.org/ged/ruby-pg/issues/270/pg-100-x64-mingw32-rails-server-not-start

Preparation for pg-1.0 was done in commit f28a3310,
but the pg version constraint was not yet relaxed.

  Remove `AppGeneratorTest#test_active_storage_install`.
  The test is added by 67db41aa,
  since #31534 this test doesn't test anything.

  Remove redundant assertions in `SharedGeneratorTests`.
  These assertions is added by 4a835aa3.
  Follows 67db41aa, #31534.

`invoke_all` cause `bundle install`. This will install gems actually
defined in `Gemfile`. To avoid this, stubbed `bundle_command`.

Fixes #31557

`skip_bundle` option was removed from plugin generator in 9b72fcc3.

Specifying the `--dev` option is when want to change the codebase,
as it is not necessary to cache it.

Context: https://github.com/rails/rails/pull/31485#issuecomment-352452653

`bootsnap` is a useful gem normally. However, `bootsnap` is unnecessary
when generating a Rails application to be used only for testing.
So I want to control whether use this or not by option.

See #31315 for full discussion

We probably don't have any tests for the `--webpack` option.
related: #27288

With the current code, a failing test shows this error, which is missing
the number of times called and has two periods at the end.

```
/railties$ be ruby -Itest test/generators/app_generator_test.rb -n test_active_storage_install

Failure:
AppGeneratorTest#test_active_storage_install [test/generators/app_generator_test.rb:313]:
active_storage:install expected to be called once, but was called  times..
Expected: 1
  Actual: 2
```

After the fix, the error message looks correct:

```
/railties$ be ruby -Itest test/generators/app_generator_test.rb -n test_active_storage_install

Failure:
AppGeneratorTest#test_active_storage_install [test/generators/app_generator_test.rb:313]:
active_storage:install expected to be called once, but was called 2 times.
Expected: 1
  Actual: 2
```

Follow up of 924a368f

- Followup of #31162

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