ruby on rails-如何构建链式方法，如-shuld_receive(:something).withs(:pa

Question

我试图让我的代码小一点，构建一个看起来像来自RSpec的should_receive的方法，这里的情况是我正在测试一个状态机，我有几个方法的代码如下：

context "State is unknown" do
  before do
    @obj = create_obj(:state => 'unknown')
  end
  context "Event add" do
    it 'should transition to adding if not in DB' do
      @obj.add
      @obj.state.should == 'adding'
    end
    it 'should transition to linking if already in DB' do
      create_obj_in_db
      @obj.add
      @obj.state.should == 'linking'
    end
  end
end

我想把这些代码行替换成类似的东西：

@obj.should_receive(:add).and_transition_to('adding')
@obj.should_receive(:modify).and_transition_to('modifying')

这些方法是如何构建的？

Answer 1

简单：

类Objdef should_receive（消息）self.send（消息.to_sym）自己终止def和_transition_to（状态）@state==状态终止def添加@state="正在添加"终止终止

现在你可以运行：

obj=对象新建obj.should_receive（：add）.and_transition_to（'adding'）=>真

Answer 2

链接的重要部分是从对象返回self，因此下一次调用仍然可以对对象进行操作。

class Foo
  def one
    puts "one"
    self
  end
  def two
     puts "two"
     self
  end
  def three
     puts "three"
     self
  end
end
a=Foo.new
a.one.two.three

Answer 3

它不是ruby on rails，但本文给出了一个Fluent接口的示例。

public class Pipeline
{
    private Image image;
    public Image CurrentImage
    {
        get { return image; }
        set { image = value; }
    }
    public Pipeline(string inputFilename)
    {
        image = Bitmap.FromFile(inputFilename);
    }
    public Pipeline Rotate(float Degrees)
    {
        RotateFilter filter = new RotateFilter();
        filter.RotateDegrees = Degrees;
        image = filter.ExecuteFilter(image);
        return this;
    }
    :