帮助Ruby Koans #6 -捕获了什么异常？

Question

我正试着通过Koans学习Ruby，但是我被困在了第六步。

代码如下：

def test_you_dont_get_null_pointer_errors_when_calling_methods_on_nil  
  # What happens when you call a method that doesn't exist.    
  # The following begin/rescue/end code block captures the exception and  
  # make some assertions about it.  

  begin
    nil.some_method_nil_doesnt_know_about
  rescue Exception => ex
    # What exception has been caught?
    assert_equal __, ex.class

    # What message was attached to the exception?
    # (HINT: replace __ with part of the error message.)
    assert_match(/__/, ex.message)
  end
end

我知道我应该用与错误消息"NoMethodError“有关的东西来替换__，但我似乎搞不清楚。

这是我在运行“path_to_enlightenment.rb”时收到的错误消息：

The answers you seek...
  <"FILL ME IN"> expected but was  <NoMethodError>.

我真的很感激这方面的一些指导-它快把我逼疯了！我很想知道答案和可能的解释。谢谢!

Answer 1

这里的答案是"NoMethodError“

你需要两边的项是相等的，因此将它们都设为ex.class可以做到这一点。

然后，您需要转到下面的/__/。

Answer 2

我必须将assert_equal语句放在括号中才能使这条语句通过。一定是个窃听器。

  def test_you_dont_get_null_pointer_errors_when_calling_methods_on_nil
    # What happens when you call a method that doesn't exist.  The
    # following begin/rescue/end code block captures the exception and
    # make some assertions about it.
    begin
      nil.some_method_nil_doesnt_know_about
    rescue Exception => ex
      # What exception has been caught?
      assert_equal(NoMethodError, ex.class)

      # What message was attached to the exception?
      # (HINT: replace __ with part of the error message.)
      assert_match("undefined method", ex.message)
    end
  end

Answer 3

需要将__替换为实际的

assert_equal NoMethodError, ex.class