Question

我试图使用RSpec进入BDD，并且我很难通过简单的示例来缩放技术。

http://betterspecs.org/#contexts通知我，我应该使用＆＃39;上下文＆＃39;方法让我的期望更容易描述。我有两个问题：

1）在＆＃39;环境中包装测试＆＃39;创建一个新的范围，所以我的设置必须多次完成。我还没有找到一种方法来使用＆＃39;之前＆＃39;挂钩使这个干 - 你可以看到下面重复的代码。

2）您在下面看到的案例是一个循序渐进的过程，因此每个步骤都会构建下一个步骤。首先实例化Compositor，然后添加一条指令，然后清除指令。如果1）得到解决，这不是一个很大的技术问题，但是你会注意到上下文描述开始滚雪球，这似乎打败了上下文的目的＆＃39;方法

有人建议使用重构来使这组测试符合最佳实践吗？

require 'spec_helper'

describe Compositor do

  context 'when instantiated with correct parameters' do
    renderer = USBTeensyRenderer.new("/dev/tty.usbmodem54121", 9600)
    comp = Compositor.new(renderer, [0, 0, 255, 255])
    it 'has a bounding rectangle' do
      expect(comp.bounding_box).to eq([0, 0, 255, 255])
    end
    it 'has a renderer' do
      expect(comp.renderer).to eq(renderer)
    end
    it 'has an empty array of drawing instructions' do
      expect(comp.drawing_instructions).to eq([])
    end
  end

  context 'when one drawing instruction is added' do
    renderer = USBTeensyRenderer.new("/dev/tty.usbmodem54121", 9600)
    comp = Compositor.new(renderer, [0, 0, 255, 255])
    comp.add_instruction(Line.new( TwoDPoint.new(20, 20), TwoDPoint.new(40, 40) ))
    it 'has a length of one' do
      expect(comp.drawing_instructions.length).to eq(1)
    end
    it 'has an instruction of class Line' do
      expect(comp.drawing_instructions[0].class).to eq(Line)
    end
  end

  context 'when one drawing instruction is added and drawing instructions are cleared' do
    renderer = USBTeensyRenderer.new("/dev/tty.usbmodem54121", 9600)
    comp = Compositor.new(renderer, [0, 0, 255, 255])
    comp.add_instruction(Line.new( TwoDPoint.new(20, 20), TwoDPoint.new(40, 40) ))
    comp.clear()
    it 'has a length of zero' do
      expect(comp.drawing_instructions.length).to eq(0)
    end
  end

end

Answer 1

这些应该会使你的规格非常紧张：

在描述块的开头将renderer和comp移至let次调用。 let不会在it个示例中共享状态，从而降低意外行为的风险。请注意，它是懒惰评估，但可能有潜在的副作用。 link

describe Compositor do
  let(:renderer){ USBTeensyRenderer.new("/dev/tty.usbmodem54121", 9600) }`
  ...

在每个上下文中使用before块来封装依赖于上下文的设置

context 'when one drawing instruction is added' do
  before { comp.add_instruction(Line.new( TwoDPoint.new(20, 20),TwoDPoint.new(40, 40) )) }
  ...

内联it期望进行一次班轮测试。这应该减少滚雪球的描述。

it { expect(comp.bounding_box).to eq([0, 0, 255, 255]) }

Answer 2

您可以在context下方和require 'spec_helper' describe Compositor do before do # this will run before each example even those within contexts renderer = USBTeensyRenderer.new("/dev/tty.usbmodem54121", 9600) comp = Compositor.new(renderer, [0, 0, 255, 255]) end # Or even better you can do it using let to be lazy # let(:renderer) { USBTeensyRenderer.new("/dev/tty.usbmodem54121", 9600) } # let(:comp) { Compositor.new(renderer, [0, 0, 255, 255]) } context 'when instantiated with correct parameters' do it 'has a bounding rectangle' do expect(comp.bounding_box).to eq([0, 0, 255, 255]) end it 'has a renderer' do expect(comp.renderer).to eq(renderer) end it 'has an empty array of drawing instructions' do expect(comp.drawing_instructions).to eq([]) end end context 'when one drawing instruction is added' do before do comp.add_instruction(Line.new( TwoDPoint.new(20, 20),TwoDPoint.new(40, 40) )) end it 'has a length of one' do expect(comp.drawing_instructions.length).to eq(1) end it 'has an instruction of class Line' do expect(comp.drawing_instructions[0].class).to eq(Line) end context 'and when drawing instructions are cleared' do before do comp.clear() end it 'has a length of zero' do expect(comp.drawing_instructions.length).to eq(0) end end end end之前使用前挂钩。

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RSpec

2 个答案: