newbie不能在ruby中定义一个方法用于黄瓜测试通过 [英] newbie can't define a method in ruby for cucumber test pass

问题描述

我正在学习黄瓜，下面是一本书的示例代码：

I am trying to learn cucumber, here's an example code from a book:

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

当我运行这个规范，我得到这个错误：

When I run this spec, I get this error:

  Scenario: start game                          # features/codebreaker_starts_game.feature:7
    Given I am not yet playing                  # features/step_definitions/codebreaker_steps.rb:15
    When I start a new game                     # features/step_definitions/codebreaker_steps.rb:18
    Then I should see "Welcome to Codebreaker!" # features/step_definitions/codebreaker_steps.rb:23
      undefined method `messages' for #<RSpec::Matchers::BuiltIn::Output:0xa86a7a4> (NoMethodError)
      ./features/step_definitions/codebreaker_steps.rb:24: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:23

看到它提供未定义方法的邮件'错误，但它在输出类中定义。

See that it gives undefined method 'messages' error, yet it is defined in the Output class.

output.messages.should 与 Output.new.messages.should ，它工作正常。这里有什么问题？

If I replace output.messages.should with Output.new.messages.should, it works fine. What is the problem here?

编辑：可能输出新版本的rails，当我把它改为 outputz 它工作正常。

Edit: Probably output is a keyword, in new version of rails, when I changed it to outputz it worked fine. An explanation of this will be accepted as an answer.

推荐答案

显然， 输出匹配器已添加到版本3.0中的rspec：

Apparently, the output matcher has been added to rspec in version 3.0:

输出匹配器提供一种方法来断言已将
内容发送到 $ stdout 或 $ stderr 。

块输出to_stdout或to_stderr。使用
一个字符串，如果块输出特定字符串to_stdout
或to_stderr，则传递。使用regexp或matcher，如果块输出一个
字符串to_stdout或to_stderr匹配，则传递。

With no arg, passes if the block outputs to_stdout or to_stderr. With a string, passes if the blocks outputs that specific string to_stdout or to_stderr. With a regexp or matcher, passes if the blocks outputs a string to_stdout or to_stderr that matches.

p>

Examples:

RSpec.describe "output.to_stdout matcher" do
  specify { expect { print('foo') }.to output.to_stdout }
  specify { expect { print('foo') }.to output('foo').to_stdout }
  specify { expect { print('foo') }.to output(/foo/).to_stdout }
  specify { expect { }.to_not output.to_stdout }
  specify { expect { print('foo') }.to_not output('bar').to_stdout }
  specify { expect { print('foo') }.to_not output(/bar/).to_stdout }

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