Question

在某种程度上可以使用RSpec测试Ruby的警告吗？

像这样：

class MyClass
  def initialize
    warn "Something is wrong"
  end
end

it "should warn" do
  MyClass.new.should warn("Something is wrong")
end

Answer 1

warn在Kernel中定义，包含在每个对象中。如果您在初始化期间没有提出警告，则可以指定如下警告：

obj = SomeClass.new
obj.should_receive(:warn).with("Some Message")
obj.method_that_warns

在initialize方法中引发警告要复杂得多。如果必须这样做，您可以交换假IO对象$stderr并检查它。请务必在示例

之后恢复它

class MyClass
  def initialize
    warn "Something is wrong"
  end
end

describe MyClass do
  before do
    @orig_stderr = $stderr
    $stderr = StringIO.new
  end

  it "warns on initialization" do
    MyClass.new
    $stderr.rewind
    $stderr.string.chomp.should eq("Something is wrong")
  end

  after do
    $stderr = @orig_stderr
  end
end

Answer 2

有一篇关于自定义期望的好文章可以解决您的问题：http://greyblake.com/blog/2012/12/14/custom-expectations-with-rspec/

所以它想：

expect { MyClass.new }.to write("Something is wrong").to(:error)

根据那篇文章，你可以创建自己的期望，就像这样使用它：

expect { MyClass.new }.to warn("Something is wrong")

Answer 3

这是我的解决方案，我定义了一个自定义匹配器has_warn

require 'rspec'
require 'stringio'

module CustomMatchers
  class HasWarn
    def initialize(expected)
      @expected = expected
    end

    def matches?(given_proc)
      original_stderr = $stderr
      $stderr = StringIO.new
      given_proc.call
      @buffer = $stderr.string.strip
      @expected.include? @buffer.strip
    ensure
      $stderr = original_stderr
    end

    def supports_block_expectations?
      true
    end

    def failure_message_generator(to)
      %Q[expected #{to} get message:\n#{@expected.inspect}\nbut got:\n#{@buffer.inspect}]
    end

    def failure_message
      failure_message_generator 'to'
    end

    def failure_message_when_negated
      failure_message_generator 'not to'
    end

  end

  def has_warn(msg)
    HasWarn.new(msg)
  end
end

现在，您可以在包含CustomMatchers后使用此功能：

expect{ MyClass.new }.to has_warn("warning messages")

使用RSpec测试警告

3 个答案: