Deprecation warning in Ruby 3.4: "string returned by :…to_s will be frozen in the future" in RSpec::Mocks::InstanceMethodStasher

[thomaswitt]

What’s happening?

I enabled Warning[:deprecated] = true in my spec/spec_helper.rb.

Running specs on Ruby 3.4.4 with RSpec 3.13.5 shows on my console warnings like

/Users/thomas/.rbenv/versions/3.4.4/lib/ruby/gems/3.4.0/gems/rspec-mocks-3.13.5/lib/rspec/mocks/instance_method_stasher.rb:8: warning: string returned by :id.to_s will be frozen in the future

I guess it has to do with "stashed_method_name", but a simple .dup doesnt solve the problem.

[pirj]

Thanks for reporting. Do you mind sharing a minimum spec that triggers this? Or is it just any that uses mocks?

[thomaswitt]

@pirj Correct, any that uses mocks in my case, happens a lot of times during my spec. So I guess its not one particular test.

Thanks for your time!

[pirj]

@thomaswitt Here's a run of rspec-mocks's 3.13.5 on Ruby 3.4.4, and it passed. There should be something else involved, can it be Rails?
I can't find any issue on line 8 of the instance_method_stasher.rb either.

May I kindly ask you to provide more details?
What if you configure RSpec to raise on such a warning?

# spec/spec_helper.rb

RSpec.configure do |rspec|
  rspec.raise_on_warning = true
end

Will it output some backtrace?

[pirj]

Ha, I’ve missed the Warning[:deprecated] step, the CI build certainly ran without it. Let me run a build with it first.

[pirj]

I don't see this warning in test CI builds with Ruby deprecation warnings enabled. Can you please help pinpointing this warning, @thomaswitt ?