RSpec - 存根


如果您已经阅读了有关 RSpec Doubles(又名 Mocks)的部分,那么您已经看到了 RSpec Stubs。在 RSpec 中,存根通常称为方法存根,它是一种特殊类型的方法,“代表”现有方法,或者甚至尚不存在的方法。

这是 RSpec Doubles 部分的代码 -

class ClassRoom 
   def initialize(students) 
      @students = students 
   End
   
   def list_student_names 
      @students.map(&:name).join(',') 
   end 
end 

describe ClassRoom do 
   it 'the list_student_names method should work correctly' do 
      student1 = double('student') 
      student2 = double('student') 
      
      allow(student1).to receive(:name) { 'John Smith'}
      allow(student2).to receive(:name) { 'Jill Smith'} 
      
      cr = ClassRoom.new [student1,student2]
      expect(cr.list_student_names).to eq('John Smith,Jill Smith') 
   end 
end

在我们的示例中,allow() 方法提供了我们测试 ClassRoom 类所需的方法存根。在本例中,我们需要一个像 Student 类的实例一样运行的对象,但该类实际上还不存在。我们知道Student类需要提供name()方法,我们使用allow()为name()创建一个方法存根。

需要注意的一件事是,RSpec 的语法多年来发生了一些变化。在旧版本的 RSpec 中,上述方法存根将这样定义 -

student1.stub(:name).and_return('John Smith') 
student2.stub(:name).and_return('Jill Smith')

让我们使用上面的代码并用旧的 RSpec 语法替换两行allow() -

class ClassRoom 
   def initialize(students) 
      @students = students 
   end 
   
   def list_student_names 
      @students.map(&:name).join(',') 
   end 
	
end 

describe ClassRoom do 
   it 'the list_student_names method should work correctly' do 
      student1 = double('student') 
      student2 = double('student')
      
      student1.stub(:name).and_return('John Smith')
      student2.stub(:name).and_return('Jill Smith') 
      
      cr = ClassRoom.new [student1,student2] 
      expect(cr.list_student_names).to eq('John Smith,Jill Smith') 
   end 
end

当您执行上述代码时,您将看到此输出 -

.
Deprecation Warnings:

Using `stub` from rspec-mocks' old `:should` syntax without explicitly 
   enabling the syntax is deprec 

ated. Use the new `:expect` syntax or explicitly enable `:should` instead. 
   Called from C:/rspec_tuto 

rial/spec/double_spec.rb:15:in `block (2 levels) in <top (required)>'.
If you need more of the backtrace for any of these deprecations 
   to identify where to make the necessary changes, you can configure 

`config.raise_errors_for_deprecations!`, and it will turn the 
   deprecation warnings into errors, giving you the full backtrace.

1 deprecation warning total

Finished in 0.002 seconds (files took 0.11401 seconds to load)
1 example, 0 failures

当您需要在 RSpec 示例中创建方法存根时,建议您使用新的 allowed() 语法,但我们在此处提供了旧样式,以便您在看到它时能够识别它。