[Rails] "output" name collission with RSpec::Matchers::BuiltIn::Output

[Ralph Shnelvar]

I'm following along in *The RSpec Book* 
<https://pragprog.com/book/achbd/the-rspec-book> on page 43

The book is careful to specify all the version of the gems it uses.  My 
problem is likely I am using current gems.

The code I downloaded looks like this
#---
# Excerpted from "The RSpec Book",
# published by The Pragmatic Bookshelf.
# Copyrights apply to this code. It may not be used to create training 
material, 
# courses, books, articles, and the like. Contact us if you are in doubt.
# We make no guarantees that this code is fit for any purpose. 
# Visit http://www.pragmaticprogrammer.com/titles/achbd for more book 
information.
#---
class Output
  def messages
    @messages ||= []
  end

  def puts(message)
    messages << message
  end
end

def output
  @output ||= Output.new
end

Given /^I am not yet playing$/ do
end

When /^I start a new game$/ do
  game = Codebreaker::Game.new(output)
  game.start
end

Then /^I should see "([^"]*)"$/ do |message|
  output.messages.should include(message)
end

The author says he's creating a "test double" with the lines
class Output
  def messages
    @messages ||= []
  end

  def puts(message)
    messages << message
  end
end

def output
  @output ||= Output.new
end

If I use the above code, RSpec will say
  Scenario: start game                          # 
features/codebreaker_starts_game.feature:7
    Given I am not yet playing                  # 
features/step_definitions/codebreaker_steps.rb:34
    When I start a new game                     # 
features/step_definitions/codebreaker_steps.rb:37
    Then I should see "Welcome to Codebreaker!" # 
features/step_definitions/codebreaker_steps.rb:41
      undefined method `messages' for 
#<RSpec::Matchers::BuiltIn::Output:0x0055e95ffb9728> (NoMethodError)
      ./features/step_definitions/codebreaker_steps.rb:44:in `/^I should 
see "([^"]*)"$/'
      features/codebreaker_starts_game.feature:10:in `Then I should see 
"Welcome to Codebreaker!"'
    And I should see "Enter guess:"             # 
features/step_definitions/codebreaker_steps.rb:41
The "undefined method" message immediately above is not what the book says 
should be generated.

If, on the other hand, I rename the method named output with output_ralph 
(see immediately below)
# This works

#---
# Excerpted from "The RSpec Book",
# published by The Pragmatic Bookshelf.
# Copyrights apply to this code. It may not be used to create training 
material, 
# courses, books, articles, and the like. Contact us if you are in doubt.
# We make no guarantees that this code is fit for any purpose. 
# Visit http://www.pragmaticprogrammer.com/titles/achbd for more book 
information.
#---

require "byebug"
# byebug

class Output
  def messages
    @messages ||= []
  end

  def puts(message)
    messages << message
  end
end

# byebug
def output_ralph
  # byebug
  @output ||= Output.new
  ret = @output
  # byebug
  ret
end

Given /^I am not yet playing$/ do
end

When /^I start a new game$/ do
  # byebug
  game = Codebreaker::Game.new(output_ralph)
  game.start
end

Then /^I should see "([^"]*)"$/ do |message|
  # output.messages.should include(message)
  # byebug
  # x = output_ralph.messages
  # byebug
  
  expect(output_ralph.messages).to include(message)
end

then I get the output the book says I should get (immediately below)
  Scenario: start game                          # 
features/codebreaker_starts_game.feature:7
    Given I am not yet playing                  # 
features/step_definitions/codebreaker_steps.rb:34
    When I start a new game                     # 
features/step_definitions/codebreaker_steps.rb:37
    Then I should see "Welcome to Codebreaker!" # 
features/step_definitions/codebreaker_steps.rb:43
      expected [] to include "Welcome to Codebreaker!" (RSpec::Expectations
::ExpectationNotMetError)
      ./features/step_definitions/codebreaker_steps.rb:49:in `/^I should 
see "([^"]*)"$/'
      features/codebreaker_starts_game.feature:10:in `Then I should see 
"Welcome 
to Codebreaker!"'
    And I should see "Enter guess:"             # 
features/step_definitions/codebreaker_steps.rb:43


I suspect I have a name collision with *Class: 
RSpec::Matchers::BuiltIn::Output* 
<http://rspec.info/documentation/3.4/rspec-expectations/RSpec/Matchers/BuiltIn/Output.html>
 but 
I'm damned if I can figure out why.

I guess I could leave the code as-is but ... advice would be appreciated.

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