Prefer using slashes in Rails/FilePath cop

[sunny]

Under Windows, Rails.root.join('app', 'models', 'goober') is equal to Rails.root.join('app/models/goober'). They both return a string with forward slashes.

I'm in favor of always using the simple slashes and deprecating the previous join. The current cop suggests this is

to avoid bugs on operating system that don't use '/' as the path separator

but there is no evidence of such bugs.

More discussion of the issue here: https://twitter.com/tenderlove/status/842064491936280576

---

Expected behavior

Rails/FilePath should treat as:

# bad
Rails.root.join('app', 'models', 'goober')

# good
Rails.root.join('app/models/goober')

Actual behavior

Today it treats the following as:

# good
Rails.root.join('app', 'models', 'goober')

# bad
Rails.root.join('app/models/goober')

[roberts1000]

Good find. FWIW, we disable this cop at our shop and use the "#{Rails.root}/app/models/goober" format.

[Drenmi]

At the very least the style should be configurable.

[juanxcerv]

When trying to integrate this change we discovered that there is a difference in how absolute paths are resolved with each approach.

For example:

path = File.expand_path('./app/models/user.rb')
# => "/Users/juancervantes/Desktop/synchroform/app/models/user.rb"
Rails.root.join('app', 'models', path)
# => #<Pathname:/Users/juancervantes/Desktop/synchroform/app/models/user.rb>
Rails.root.join("app/models/#{path}")
# => #<Pathname:/Users/juancervantes/Desktop/synchroform/app/models//Users/juancervantes/Desktop/synchroform/app/models/user.rb>

We decided to stick with the separate arguments for the sake of consistency.

[sunny]

@juanxcerv:

When trying to integrate this change we discovered that there is a difference in how absolute paths are resolved with each approach.

When building paths, instead of using String interpolation Rails.root.join("app/models/#{path}") you should still use join to do the concatenation: Rails.root.join("app/models", path).

Although beware that in your example you are joining a path that starts with /. This is actually dismissing whatever was used beforehand. This can be quite unexpected: in your example Rails.root.join('app', 'models', path) ignores anything before path 🙀

path = File.expand_path('./app/models/user.rb')
# => "/Users/juancervantes/Desktop/synchroform/app/models/user.rb"
Rails.root.join('app', 'models', path)
# => #<Pathname:/Users/juancervantes/Desktop/synchroform/app/models/user.rb>
Rails.root.join('app/models', path)
# => #<Pathname:/Users/juancervantes/Desktop/synchroform/app/models/user.rb>
Rails.root.join('whatever', 'since', 'this', 'is', 'ignored', path)
# => #<Pathname:/Users/juancervantes/Desktop/synchroform/app/models/user.rb>
Pathname.new(path)
# => #<Pathname:/Users/juancervantes/Desktop/synchroform/app/models/user.rb>

So do not concatenate expanded paths, simply do:

path = "app/models/user.rb"
Rails.root.join('app/models', path)

[philliplongman]

I feel like this should be revisited in light of @sunny's comment. It sounds like what this cop should be doing is guarding against string interpolation.