Puma 5.0.3 deprecation warning in Ruby 2.7 - warning: deprecated Object#=~ is called on Proc

[ndbroadbent]

I just pushed a new branch to update to puma 5.0.3, and I've configured my CI builds to crash on any warnings. I'm now seeing this warning in the logs:

vendor/bundle/ruby/2.7.0/gems/puma-5.0.3/lib/puma/server.rb:94: warning: deprecated Object#=~ is called on Proc; it always returns nil

(This is not happening with puma 5.0.2.)

Here is the line: https://github.com/puma/puma/blob/master/lib/puma/server.rb#L94

It looks like it changed 27 days ago in #2389 - this commit: bbce3d6

I found out that :environment is actually being set to a Proc here, in puma_default_options:

puma/lib/puma/configuration.rb

Line 196 in d0f75b4

:environment => -> { ENV['RACK_ENV'] || ENV['RAILS_ENV'] || "development" },

---

It looks like this case is not being hit in the test suite since I couldn't find "Object#=~" in any of the log output here: https://github.com/puma/puma/runs/1308878188?check_suite_focus=true
It might be a good idea to add a new test case that exercises this code path, and then fail the tests if there are any warnings:

module Warning
  def warn(msg)
    raise msg
  end
end

[nateberkopec]

Thanks for the heads up. The suggested course of action sounds good.

[MSP-Greg]

Thanks and interesting. We've also got the following, which is what I based the breaking code line on (I think):

puma/lib/puma/runner.rb

Lines 20 to 26 in d0f75b4

	def development?
	@options[:environment] == "development"
	end
	def test?
	@options[:environment] == "test"
	end

We'll add the warning change to the CI, as I've also seen some running locally...

[MSP-Greg]

Something is odd.

I don't know if I've ever really gone thru the configuration code, but Puma::Configuration#clamp, which calls UserFileDefaultOptions#finalize_values, should 'convert' the lambda's/proc's into values. I must be missing something, or something's wrong with the code.

One problem with warnings is some are thrown by Ruby classes themselves in older Ruby versions. We still should be able to check them in the integration tests.

[MSP-Greg]

@ndbroadbent

Using 5.0.3, I've started Puma via bin/puma and bin/rackup, and @options[:environment] is a String, or, no warnings. How are you starting Puma?

[ndbroadbent]

@MSP-Greg Really sorry for the missing details - I should have mentioned that puma does start correctly during development (and presumably production), but I run into this warning while running my RSpec test suite, which uses Capybara to start the puma server. I'm not familiar with how capybara is calling puma, but it could be skipping this UserFileDefaultOptions#finalize_values step. I wonder if this might be a bug in capybara in that case.

UPDATE: Yeah maybe the problem is actually in here, where capybara is setting up the puma server: https://github.com/teamcapybara/capybara/blob/d6a3e18f5c605236ae41ec90e872ae6a554c12fc/lib/capybara/registrations/servers.rb#L13-L44

[ndbroadbent]

Yep, I put a breakpoint in there, and conf.options[:environment] was a Proc. Calling conf.options.finalize_values fixed the issue so that conf.options[:environment] now returns "test". So I'll close this and open a PR in Capybara.

Here's the PR: teamcapybara/capybara#2413