--fix replacement of Pathname#sub(...) with Pathname#delete_suffix(...) breaks the code

[myronmarston]

Given standardrb_bug.rb:

require "pathname"

path = Pathname.new("path/to/some/ruby/file.rb").sub(/\.rb\z/, "")
puts path

...when I run it, I get the following:

$ ruby standardrb_bug.rb
path/to/some/ruby/file

...but when I run the following:

$ standardrb --version
1.1.1
$ standardrb standardrb_bug.rb --fix

...it changes standardrb_bug.rb like so:

require "pathname"

path = Pathname.new("path/to/some/ruby/file.rb").delete_suffix(".rb")
puts path

...which raises an error when run:

$ ruby standardrb_bug.rb
Traceback (most recent call last):
standardrb_bug.rb:3:in `<main>': undefined method `delete_suffix' for #<Pathname:path/to/some/ruby/file.rb> (NoMethodError)

Pathname objects have a sub method but not a delete_suffix method and it's not safe for standardrb to change it.

[jmkoni]

Huh. Totally agree that we should not be changing it. Now I just need to find the rule.