Performance Count Cop does not work

[enthusiasmus]

---

Expected behavior

I am expecting offenses for

        [1, 2, 3].select { |e| e > 2 }.size
        [1, 2, 3].reject { |e| e > 2 }.size
        [1, 2, 3].select { |e| e > 2 }.length
        [1, 2, 3].reject { |e| e > 2 }.length

as seen in https://github.com/rubocop-hq/rubocop-performance/blob/master/lib/rubocop/cop/performance/count.rb

Actual behavior

I don't receive offenses

Steps to reproduce the problem

file foobar.rb with

# frozen_string_literal: true

def foobar
  [1, 2, 3].select { |e| e > 2 }.size
  [1, 2, 3].reject { |e| e > 2 }.size
  [1, 2, 3].select { |e| e > 2 }.length
  [1, 2, 3].reject { |e| e > 2 }.length
end

executing rubocop performance via rubocop --require rubocop-performance foobar.rb

RuboCop version

Include the output of rubocop -V or bundle exec rubocop -V if using Bundler. Here's an example:

$ [bundle exec] rubocop -V
0.72.0 (using Parser 2.6.3.0, running on ruby 2.6.3 x86_64-linux)

rubocop-performance version: 1.4.0

[koic]

Please set SafeMode of Performance/Count cop to false in rubocop.yml.

Performance/Count:
  SafeMode: false

It is not working because SafeMode is true by default.
https://docs.rubocop.org/projects/performance/en/stable/cops_performance/#performancecount

Related resources

• https://github.com/rubocop-hq/rubocop-performance/blob/v1.4.0/config/default.yml#L44-L48
• Make cops with Rails compatibility issue dependant on Rails cops being disabled rubocop#2862

[rrosenblum]

I came across this in the last day or two as well. Looking into it, I think the SafeMode on these cops has outlived its usefulness. SafeMode doesn't produce a single offense for either cop so it is the same as having it disabled by default. It is only documented inside of the default.yml file so user's don't know that the configuration exists. I think we would be better off disabling the cop by default, or changing it to be flagged as unsafe for auto-correction.

[enthusiasmus]

Thanks for the hint and reply!

[koic]

#72 has been released.