Rspec中describe和context不同

转自  http://lmws.net/describe-vs-context-in-rspec

学习rspec,不太理解describe和context。google了一下，找到这篇文章，感觉说的有些道理

1 在Rspec的世界里，我们经常看到人们使用descirbe代码块和context代码块 例如

describe "launch the rocket" do
  context "all ready" do
  end
 
  context "not ready" do
  end
end

那么context和descript有啥不同呢

According to the rspec source code, “context” is just a alias method of “describe”, meaning that there is no functional difference between these two methods. However, there is a contextual difference that’ll help to make your tests more understandable by using both of them.

说的是，按照rspec源码来看，context仅仅是describe方法的别名，意味着这两者没有任何功能性的不同， 然而有一些语境不同(语义不同),理解这个能让你写出更可读的代码

The purpose of “describe” is to wrap a set of tests against one functionality while “context” is to wrap a set of tests against one functionality under the same state. Here’s an example

describe的目的是当它包裹一组，一个功能，的测试代码

context的目的是包裹一组，在同一状态下，一个功能的，测试代码

例如下面代码

describe "launch the rocket" do
  before(:each) do
    #prepare a rocket for all of the tests
    @rocket = Rocket.new
  end
 
  context "all ready" do
    before(:each) do
      #under the state of ready
      @rocket.ready = true
    end
 
    it "launch the rocket" do
      @rocket.launch().should be_true
    end
  end
 
  context "not ready" do
    before(:each) do
      #under the state of NOT ready
      @rocket.ready = false
    end
 
    it "does not launch the rocket" do
      @rocket.launch().should be_false
    end
  end
end

上面的代码可读性好在，没有将所有东西都用describe包裹，因为你读测试代码是在context语境内，对于一个context设置一个对象状态，

@rocket.ready为true时， @rocket.launch() 的行为，导致一个结果，如果只关注一个这个状态时，火箭的启动结果，就不需要再看其他状态的代码