Wouldn't it be preferable to use slashes in Rails.root.join?

[castor4bit]

In Pull Request #2640, it was commented to use multiple strings instead of slashes for Rails.root.join, but rubocop-rails defaults to using slashes.

• Use 'Rails.root.join' in rails_helper #2640 (comment)
• https://docs.rubocop.org/rubocop-rails/cops_rails.html#railsfilepath

This may be in consideration of platforms that do not use /, such as Windows, but since Rails.root.join is joined with File::SEPARATOR (/), both writing styles return the same result separated by slashes.

The Windows path separator can also be interpreted, so it will work as intended but will not be significant. Wouldn't it be preferable to adopt the rubocop-rails default and write Rails.root.join('foo/bar/baz') for the same behavior? (Otherwise rubocop will still warn)

Examples

Environment

• rails (7.0.4)
• rspec-core (3.12.0)
• rspec-rails (6.0.1)
• rubocop-rspec (2.15.0)
• rubocop-rails (2.17.3)

Behavior of Rails.root.join under Windows

C:\Users\test\sample>systeminfo
...
OS Name:                   Microsoft Windows 10 Pro
OS Version:                10.0.19044 N/A Build 19044
...

C:\Users\test\sample>ruby -v
ruby 3.1.3p185 (2022-11-24 revision 1a6b16756e) [x64-mingw-ucrt]

C:\Users\test\sample>rails c
Loading development environment (Rails 7.0.4)

irb(main):001:0> p Rails.root
#<Pathname:C:/Users/test/sample>
=> #<Pathname:C:/Users/test/sample>
irb(main):002:0> p Rails.root.join('foo/bar')
#<Pathname:C:/Users/test/sample/foo/bar>
=> #<Pathname:C:/Users/test/sample/foo/bar>
irb(main):003:0> p Rails.root.join('foo', 'bar')
#<Pathname:C:/Users/test/sample/foo/bar>
=> #<Pathname:C:/Users/test/sample/foo/bar>

Windows path separators can be mixed (and still work fine)

irb(main):004:0> p Pathname.new(ENV['TMP']).join('foo', 'bar')
#<Pathname:C:\Users\test\AppData\Local\Temp/foo/bar>
=> #<Pathname:C:\Users\test\AppData\Local\Temp/foo/bar>

Result for rubocop

$ bundle exec rubocop spec/rails_helper.rb
Inspecting 1 file
C

Offenses:

spec/rails_helper.rb:36:25: C: Rails/FilePath: Prefer Rails.root.join('path/to').
  config.fixture_path = Rails.root.join('spec', 'fixtures')
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

1 file inspected, 1 offense detected

[pirj]

This explanation makes sense.
Would you like to send a PR?

[castor4bit]

Sure. I created #2642, thanks!