Rspec中describe和context不同

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

學習rspec,不太理解describe和context。google了一下，找到這篇文章，感覺說的有些道理

1 在Rspec的世界裡，我們經常看到人們使用descirbe程式碼塊和context程式碼塊 例如

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

那麼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.

說的是，按照rspec原始碼來看，context僅僅是describe方法的別名，意味著這兩者沒有任何功能性的不同， 然而有一些語境不同(語義不同),理解這個能讓你寫出更可讀的程式碼

 

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的目的是當它包裹一組，一個功能，的測試程式碼

context的目的是包裹一組，在同一狀態下，一個功能的，測試程式碼

 

例如下面程式碼

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

上面的程式碼可讀性好在，沒有將所有東西都用describe包裹，因為你讀測試程式碼是在context語境內，對於一個context設定一個物件狀態，

@rocket.ready為true時， @rocket.launch() 的行為，導致一個結果，如果只關注一個這個狀態時，火箭的啟動結果，就不需要再看其他狀態的程式碼