item.blank? is not a correct replacement for item.nil? || item.empty?

[mvz]

The Rails/Blank cop autocorrects item.nil? || item.empty? to item.blank?, even with the 'safe' autocorrect mode (i.e., rubocop -a). However, a string consisting of just spaces is considered blank but not empty by Rails, which means this autocorrect causes a change in behavior.

Expected behavior

Given a file in Rails containing the line

  item.nil? || item.empty?

When running rubocop -a, RuboCop should not autocorrect this to item.blank?.

Actual behavior

RuboCorrect the code to item.blank?

Steps to reproduce the problem

This is extremely important! Providing us with a reliable way to reproduce
a problem will expedite its solution.

• Create a file foo.rb containing:

# frozen_string_literal: true

def foo(item)
  item.nil? || item.empty?
end

• Create a file .rubocop.yml containing:

require:
  - rubocop-rails

AllCops:
  NewCops: enable

Rails:
  Enabled: true

Run rubocop -a. The file foo.rb will have been changed as described above.

RuboCop version

$ rubocop -V
1.11.0 (using Parser 3.0.0.0, rubocop-ast 1.4.1, running on ruby 3.0.0 x86_64-linux)
  - rubocop-rails 2.9.1

[andyw8]

Rails docs for reference: https://github.com/rails/rails/blob/fdba9304c2652af674fdb9cf3704ff5a64af92d7/activesupport/lib/active_support/core_ext/object/blank.rb#L103-L132