[Jon Moss & Xavier Noria]

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.

`optparse` is unused since #26977.

Include `ActiveSupport::Testing::MethodCallAssertions` in `railties/test/isolation/abstract_unit.rb`

Related to #33102

Since #32289, `Spellchecker.suggest` returns only one value, multiple
suggestions not output.

Also normalize AJ task use t, like all other Rails test tasks.

Thor 0.18 is causing failures in all the generator tests.

To prevent redundant `to_s` like https://github.com/rails/rails/pull/32923#discussion_r189460008
automatically in the future.

Follow up of #32418.

Follow up of #32605.

In #32780, We have supported the `--skip-sprockets` option in the `app:update` task.
When `options[:api]` is truthy, `option[:skip_sprockets]` is also truthy. So we can remove this `remove_file` method.
https://github.com/rails/rails/blob/42b9e7e50c084e119a679cf155b70b5efc4d36ff/railties/lib/rails/generators/rails/app/app_generator.rb#L281-L283

I saw these ones while working on #32362.

File.write was introduced in Ruby 1.9.3 and it is the most concise way
to perform bulk writes (as File.read is for bulk reading).

The existing flags enabled binmode, but we are dumping text here.
The portable way to dump text is text mode. The only difference is
newlines, and portable code should in particular emit portable newlines.

Please note the hard-coded \ns are still correct. In languages with C
semantics for newlines like Ruby, Python, Perl, and others, "\n" is a
portable newline. Both when writing and when reading. On Windows, the
I/O layer is responsible for prepending a CR before each LF on writing,
and removing CRs followed by LFs on reading. On Unix, binmode is a
no-op.

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
```

`DidYouMean::SpellChecker` is not defined.
`did_you_mean` is bundled in Ruby but can be uninstalled, and is not always
available, sometimes even on our CI:

https://travis-ci.org/rails/rails/jobs/372638523#L2405
https://travis-ci.org/rails/rails/jobs/372638523#L2416
https://travis-ci.org/rails/rails/jobs/372638523#L2427
...

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

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

`yarn install --prod` removes dev deps,
so it's impossible to run `assets:precompile` with dev npm dependencies.
This change makes rake task pass NODE_ENV to yarn when explicitly set.

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

In the previous code incorrectly removes intermediate words.

* Add a test case to ensure avoid duplicated suffix in channel generator

After renaming and deprecation of SourceAnnotationExtractor
documentation has been updated to reflect the new name Rails::SourceAnnotationExtractor

The previous documentation version listed only the default
registered extensions. This was misleading because if more extensions
get registered with
<tt>SourceAnnotationExtractor::Annotation.register_extensions</tt>,
they would be also taken into account. By saying that we consider
all registered extensions we document what happens in reality.

* [ci skip] Update links in RDOC_MAIN and remove style of word rails in README

* [ci skip] Update links in RDOC_MAIN and remove style of word rails in README

[Felipe Tovar & Rafael Mendonça França]

This autocorrects the violations after adding a custom cop in
3305c78dcd.

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.