Cucumber: NoMethodError

Question

我正在跟踪“Rspec手册”，我无法理解为什么在运行黄瓜时会出现以下错误。

Feature: code-breaker starts game

  As a code-breaker
  I want to start a game
  So that I can break the code

  Scenario: start game                          # /Users/PC/ruby/practice/rspec/codebreaker/features/codebreaker_starts_game.feature:7
    Given I am not yet playing                  # ruby/practice/rspec/codebreaker/features/step_definitions/codebreaker_steps.rb:17
    When I start a new game                     # ruby/practice/rspec/codebreaker/features/step_definitions/codebreaker_steps.rb:20
    Then I should see "Welcome to Codebreaker!" # ruby/practice/rspec/codebreaker/features/step_definitions/codebreaker_steps.rb:25
      undefined method `messages' for #<RSpec::Matchers::BuiltIn::Output:0x007fd6611fcb30> (NoMethodError)
      ./ruby/practice/rspec/codebreaker/features/step_definitions/codebreaker_steps.rb:26:in `/^I should see "(.*?)"$/'
      ./ruby/practice/rspec/codebreaker/features/codebreaker_starts_game.feature:10:in `Then I should see "Welcome to Codebreaker!"'
    And I should see "Enter guess:"             # ruby/practice/rspec/codebreaker/features/step_definitions/codebreaker_steps.rb:25

Failing Scenarios:
cucumber /Users/PC/ruby/practice/rspec/codebreaker/features/codebreaker_starts_game.feature:7 # Scenario: start game

1 scenario (1 failed)
4 steps (1 failed, 1 skipped, 2 passed)
0m0.050s

shell returned 1

步骤定义文件：

http://pastebin.com/BZZKL0wa

注意:我试着打印output.messages，它运行得很好。

Answer 1

我相信您正在遇到内置的output matcher，它是RSpec的一部分(参见https://www.relishapp.com/rspec/rspec-expectations/docs/built-in-matchers/output-matcher)。在尝试检查输出的同时，您是否尝试在步骤定义中打印output.messages？你应该得到同样的失败。

无论如何，如果使用不同的方法名，则应该没有问题。

Answer 2

Peter Alfvin是对的:重命名output方法。以下是对我起作用的东西：

class OutputDouble
  def messages
    @messages ||= []
  end
  def puts(message)
    messages << message
  end
end

def output_double
  @output ||= OutputDouble.new
end

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

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

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

注意，创建方法(输出)已重命名为output_double。