Reproduce https://github.com/jc00ke/guard-puma/issues/38

config.ru

# frozen_string_literal: true

app = ->(*) { [200, {}, ["OK"]] }

run app

Gemfile

# frozen_string_literal: true

source "https://rubygems.org"

gem "rack"
gem "puma"
gem "guard-puma"

Gemfile.lock

GEM
  remote: https://rubygems.org/
  specs:
    coderay (1.1.2)
    ffi (1.10.0)
    formatador (0.2.5)
    guard (2.15.0)
      formatador (>= 0.2.4)
      listen (>= 2.7, < 4.0)
      lumberjack (>= 1.0.12, < 2.0)
      nenv (~> 0.1)
      notiffany (~> 0.0)
      pry (>= 0.9.12)
      shellany (~> 0.0)
      thor (>= 0.18.1)
    guard-compat (1.2.1)
    guard-puma (0.5.1)
      guard (~> 2.14)
      guard-compat (~> 1.2)
      puma (~> 3.6)
    listen (3.1.5)
      rb-fsevent (~> 0.9, >= 0.9.4)
      rb-inotify (~> 0.9, >= 0.9.7)
      ruby_dep (~> 1.2)
    lumberjack (1.0.13)
    method_source (0.9.2)
    nenv (0.3.0)
    notiffany (0.1.1)
      nenv (~> 0.1)
      shellany (~> 0.0)
    pry (0.12.2)
      coderay (~> 1.1.0)
      method_source (~> 0.9.0)
    puma (3.12.0)
    rack (2.0.6)
    rb-fsevent (0.10.3)
    rb-inotify (0.10.0)
      ffi (~> 1.0)
    ruby_dep (1.5.0)
    shellany (0.0.1)
    thor (0.20.3)

PLATFORMS
  ruby

DEPENDENCIES
  guard-puma
  puma
  rack

BUNDLED WITH
   2.0.1

Guardfile

# frozen_string_literal: true

guard "puma", port: ENV["HANAMI_PORT"] || 2300 do
  watch(%r{config/*})
  watch(%r{lib/*})
  watch(%r{apps/*})
end

test.sh

bundle exec guard -n f -i -G Guardfile
11:44:08 - INFO - Using Guardfile at /Users/luca/Desktop/reloaded/Guardfile.
11:44:08 - INFO - Puma starting on port 2300 in development environment.
11:44:08 - INFO - Guard is now watching at '/Users/luca/Desktop/reloaded'
Traceback (most recent call last):
	11: from /Users/luca/.gem/ruby/2.6.0/bin/puma:23:in `<main>'
	10: from /Users/luca/.gem/ruby/2.6.0/bin/puma:23:in `load'
	 9: from /Users/luca/.gem/ruby/2.6.0/gems/puma-3.12.0/bin/puma:8:in `<top (required)>'
	 8: from /Users/luca/.gem/ruby/2.6.0/gems/puma-3.12.0/bin/puma:8:in `new'
	 7: from /Users/luca/.gem/ruby/2.6.0/gems/puma-3.12.0/lib/puma/cli.rb:69:in `initialize'
	 6: from /Users/luca/.gem/ruby/2.6.0/gems/puma-3.12.0/lib/puma/cli.rb:69:in `new'
	 5: from /Users/luca/.gem/ruby/2.6.0/gems/puma-3.12.0/lib/puma/launcher.rb:59:in `initialize'
	 4: from /Users/luca/.gem/ruby/2.6.0/gems/puma-3.12.0/lib/puma/configuration.rb:192:in `load'
	 3: from /Users/luca/.gem/ruby/2.6.0/gems/puma-3.12.0/lib/puma/configuration.rb:192:in `each'
	 2: from /Users/luca/.gem/ruby/2.6.0/gems/puma-3.12.0/lib/puma/configuration.rb:192:in `block in load'
	 1: from /Users/luca/.gem/ruby/2.6.0/gems/puma-3.12.0/lib/puma/dsl.rb:41:in `_load_from'
/Users/luca/.gem/ruby/2.6.0/gems/puma-3.12.0/lib/puma/dsl.rb:41:in `read': No such file or directory @ rb_sysopen - --control-token (Errno::ENOENT)