实例变量和 Rspec 2.x 的问题 [英] Issue with Instance variable and Rspec 2.x

问题描述

我使用的是 Rspec 2.0.我不明白作用域在这里是如何工作的......不知何故，您可以读取任何块中的变量，但我无法更新它?这是为什么?

I am using Rspec 2.0. I am not understanding how the scope works here... Somehow you can read the variable in any block but I cannot update it? why is that?

describe 'Test App' do
  before(:all) do
    @test= :blah
  end

  it 'test' do
    @test=:bye
    p @test  #  =>  prints bye 
  end

  it 'test' do
    p @test  #  =>  prints blah rather than bye...
  end
end

推荐答案

根据 RSpecbook, before(:all):

... 运行一次，并且只在它的自己的 Object 实例，但它的实例变量被复制到每个例子中的例子跑步.使用此注意事项:一般来说，我们希望每个示例完全隔离运行另一个.一旦我们开始跨示例共享状态，意想不到的事情开始发生.

... gets run once and only once in its own instance of Object, but its instance variables get copied to each instance in which the examples are run. A word of caution in using this: in general, we want to have each example run in complete isolation from one another. As soon as we start sharing state across examples, unexpected things begin to happen.

所以在你的例子中 @blah 在每个测试运行之前被复制，因此分配给它的值不会从一个例子转移到另一个例子.

So in your examples @blah is copied before each test is run, thus values assigned to it do not carry over from one example to another.

您似乎想做这样的事情(空气代码):

It seems like you want to do something like this (air code):

it "gets a token" do
  @token = OAuth.some_method_that_returns_a_token
end

it "uses that token to access some OAuth feature" do
  result = OAuth.some_feature(@token)
  result.should be_something_something
end

这听起来像是对 OAuth 的测试，而不是对您的代码的测试.您应该考虑删除 some_feature 方法(更多空气代码):

This smells like a test of OAuth, not of your code. You should consider stubbing out the some_feature method (more air code):

it "responds in some way when I use a valid token" do
  @token = mock('token')
  OAuth.should_receive(:some_feature).with(@token).and_return("success")
  result = my_code_which_uses_ouath(@token)
  result.should == "success"
end

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