RSpec - 輔助工具

有時，你的 RSpec 示例需要一種簡單的方法來共享可重用的程式碼。實現這一目標的最佳方法是使用輔助工具。輔助工具基本上是你可以跨多個示例共享的常規 Ruby 方法。為了說明使用輔助工具的好處，我們來考慮一下這段程式碼 −

class Dog 
   attr_reader :good_dog, :has_been_walked 
   
   def initialize(good_or_not) 
      @good_dog = good_or_not 
      @has_been_walked = false 
   end 
   
   def walk_dog 
      @has_been_walked = true 
   end 
end 

describe Dog do 
   it 'should be able to create and walk a good dog' do 
      dog = Dog.new(true) 
      dog.walk_dog 
      
      expect(dog.good_dog).to be true
      expect(dog.has_been_walked).to be true 
   end 
   
   it 'should be able to create and walk a bad dog' do 
      dog = Dog.new(false) 
      dog.walk_dog 

      expect(dog.good_dog).to be false
      expect(dog.has_been_walked).to be true 
 
   end 
end

這段程式碼很清晰，但儘可能減少重複的程式碼始終是一個好建議。我們可以使用名為 create_and_walk_dog() 的輔助方法來獲取以上程式碼並減少其中的某些重複項。

class Dog
   attr_reader :good_dog, :has_been_walked 
   
   def initialize(good_or_not)
      @good_dog = good_or_not 
      @has_been_walked = false 
   end 
   
   def walk_dog 
      @has_been_walked = true 
   end 
end 

describe Dog do 
   def create_and_walk_dog(good_or_bad)
      dog = Dog.new(good_or_bad)
      dog.walk_dog
      return dog 
   end 
   
   it 'should be able to create and walk a good dog' do
      dog = create_and_walk_dog(true)
      
      expect(dog.good_dog).to be true
      expect(dog.has_been_walked).to be true 
   end 
   
   it 'should be able to create and walk a bad dog' do 
      dog = create_and_walk_dog(false)
      
      expect(dog.good_dog).to be false
      expect(dog.has_been_walked).to be true 
   end 
end

當你執行以上程式碼時，你將會看到以下輸出 −

.. 
Finished in 0.002 seconds (files took 0.11401 seconds to load) 
2 examples, 0 failures

正如你所看到的，我們能夠將建立和遛狗物件新增到一個輔助工具中，這樣一來，我們的示例就會更簡短並且清晰。