Rails/TimeZone: DateTime.new is wrongly corrected to DateTime.zone.new

[doloopwhile]

When EnforcedStyle is flexible(default), Rails/TimeZone cop will correct DateTime.new to DateTime.zone.new. It breaks codes because DateTime.zone is not defined by Rails.

See: https://api.rubyonrails.org/classes/DateTime.html

Expected behavior

• DateTime.new is left as it is.
• DateTime.new is corrected to Time.zone.new as EnforcedTyope: strict

Actual behavior

• DateTime.new is corrected to DateTime.zone.new

Other DateTime's methods (now, local, parse, at, current) are also corrected to DateTime.zone.*.

Steps to reproduce the problem

$ gem install rubocop -v 0.71.0
$ gem install rubocop-rails -v 2.0
$ echo 'require: rubocop-rails' > .rubocop.yml

$ echo 'DateTime.new' > a.rb

$ rubocop --only Rails/TimeZone --auto-correct a.rb
Inspecting 1 file
C

Offenses:

a.rb:1:10: C: [Corrected] Rails/TimeZone: Do not use DateTime.new without zone. Use one of Time.zone.now, DateTime.current, DateTime.new.in_time_zone, DateTime.new.utc, DateTime.new.getlocal, DateTime.new.xmlschema, DateTime.new.iso8601, DateTime.new.jisx0301, DateTime.new.rfc3339, DateTime.new.httpdate, DateTime.new.to_i, DateTime.new.to_f instead. (https://github.com/rubocop-hq/rails-style-guide#time, http://danilenko.org/2012/7/6/rails_timezones)
DateTime.new
         ^^^

1 file inspected, 1 offense detected, 1 offense corrected

$ cat a.rb
DateTime.zone.new

RuboCop version

$ rubocop -V
0.71.0 (using Parser 2.6.3.0, running on ruby 2.6.2 x86_64-darwin17)

[tejasbubane]

rubocop/rubocop#6930 says Prefer Time class over DateTime in strict mode. This works for strict mode where it changes to Time.zone but in non-strict mode this is a bug.

[tejasbubane]

I think there is some confusion related to this cop's behaviour. cc: @vfonic

[vfonic]

@tejasbubane thanks for mentioning me.

This is indeed a bug.

I think the easiest solution is to make the cop change DateTime to Time, and it moves us closer to having only one mode:
rubocop/rubocop#6930 (comment)

@doloopwhile thanks for the repro steps! The issue you explained seemed to work for me, until I followed the exact steps and then I saw the bug. Without the detailed repro steps, I would've replied (mistakenly) that the cop works for me and you should check your configuration. Repro steps are important. :)

I'm going to submit the PR for this now.

/cc @bbatsov @jonas054

[koic]

RuboCop Rails 2.2.0 has been released with a fix for this issue.
https://rubygems.org/gems/rubocop-rails/versions/2.2.0