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When using rspec and ruby 2.7 I am unable to refine Enumerable. I have created an issue in rspec but I'm wondering if there's an underlying ruby issue. (This bug does not occur when using ruby 2.6 or 2.5.)

Code to reproduce¶

(Also attached as a .tar.gz):

# file: refinement_bug.rb
module RefinementBug
  refine Enumerable do
    def refined_method
      puts "Called #refined_method"
    end
  end
end

# file: spec/spec_helper.rb
require_relative "../refinement_bug"

# file: spec/test.rb

require_relative "../refinement_bug"

using RefinementBug

puts "Using Ruby #{RUBY_VERSION}"
[].refined_method

After installing rspec (gem install rspec), call via rspec spec/test.rb --format progress --require spec_helper.

Expected Behavior¶

When run on Ruby 2.6 and 2.5 I get the expected behavior. The Enumerable module is refined, which allows an instance of Array to call #refined_method.

# This is output when running on ruby 2.6.6, and is expected.
~/minimal_refinement_failure> rspec spec/test.rb
Using Ruby 2.6.6
Called #refined_method
No examples found.

Finished in 0.0004 seconds (files took 0.08706 seconds to load)
0 examples, 0 failures

Actual Behavior¶

When I run the same code on ruby 2.7 I get a NoMethodError, suggesting that the Enumerable module has not been refined.

~/minimal_refinement_failure> rspec spec/test.rb
Using Ruby 2.7.1

An error occurred while loading ./spec/test.rb.
Failure/Error: [].refined_method

NoMethodError:
  undefined method `refined_method' for []:Array
# ./spec/test.rb:8:in `<top (required)>'
No examples found.

Finished in 0.00003 seconds (files took 0.12287 seconds to load)
0 examples, 0 failures, 1 error occurred outside of examples

Investigation¶

There are a few changes that prevent this bug from manifesting:

• If I refine Kernel instead of Enumerable then I get the expected behavior using Ruby 2.7.
• If I refine Array instead of Enumerable then I get the expected behavior using Ruby 2.7.

This bug does not manifest if run directly via ruby (i.e. ruby -r ./spec/spec_helper.rb spec/test.rb succeeds). It only manifests when run via rspec.

I can also get the expected behavior by changing the rspec options:

• If I don't use the --require option with rspec (e.g. run it as rspec spec/test.rb --format progress) then I get the expected behavior.
• If I don't use the --format option with rspec (e.g. run it as rspec spec/test.rb --require spec_helper) then I get the expected behavior.

This suggests the underlying issue might be in rspec. But if it is, I'm curious why the change to ruby 2.7 causes this to manifest, and whether Ruby 2.7 accidentally broke some expected behavior.

Thank you for looking into this, I am very confused :)
Let me know how I can help with this!