Question

我有以下代码：

require 'command'

describe Command do
  subject(:command) { described_class.new(input, robotic_rover) }

  let(:robotic_rover) do
    double(:robotic_rover, position: '0 0 N',
                           move: '0 1 N',
                           right_turn: '0 0 E',
                           left_turn: '0 0 W')
  end

  describe 'advance command' do
    let(:input) { 'M' }

    describe 'initialization' do
      it 'alters a rovers position' do
        expect(command.position_change).to eq robotic_rover.move
      end
    end
  end

  describe 'right command' do
    let(:input) { 'R' }

    describe 'initialization' do
      it 'alters a rovers direction' do
        expect(command.position_change).to eq robotic_rover.right_turn
      end
    end
  end

  describe 'left command' do
      let(:input) { 'L' }

    describe 'initialization' do
      it 'alters the rovers direction' do
        expect(command.position_change).to eq robotic_rover.left_turn
      end
    end
  end
end

在每个初始描述块（高级命令，右命令和左命令）中，我尝试使用{{1}定义传递到input的{{1}}参数的值。 }。

只会发生最后一次测试（左命令），传递和前两次测试（高级命令和右命令）失败：

described_class.new(input, robotic_rover)

如果我从前两个测试中删除了let，那么它们会失败：

let

任何人都可以帮我改变每个描述块的Failure/Error: expect(command.position_change).to eq robotic_rover.right_turn expected: "0 0 E" got: nil参数的值吗？

守则

使用此代码的意图是将其从多个if中重构出来，但就目前而言，它是我所有的。

 Failure/Error: subject(:command) { described_class.new(input, robotic_rover) }

 NameError:
   undefined local variable or method `input' for #<RSpec::ExampleGroups::Command::AdvanceCommand::Initialization:0x007f90cc14f758>

Answer 1

我们错过了return方法中每个条件的#position_change。

what is the point of return in Ruby?

class Command
  attr_reader :input, :robotic_rover

  def initialize(input, robotic_rover)
    @input         = input
    @robotic_rover = robotic_rover
  end

  def position_change
    return robotic_rover.move if input == 'M'
    return robotic_rover.right_turn if input == 'R'
    return robotic_rover.left_turn if input == 'L'
  end
end

describe Command do
  let(:instance) { described_class.new(input, robotic_rover) }

  let(:robotic_rover) do
    double(
      "RoboticRover",
      position: '0 0 N',
      move: '0 1 N',
      right_turn: '0 0 E',
      left_turn: '0 0 W'
    )
  end

  describe '#position_change' do
    subject(:position_change) { instance.position_change }

    context 'when advance command' do
      let(:input) { 'M' }

      it 'alters a rovers position' do
        expect(position_change).to eq robotic_rover.move
      end
    end

    context 'when right command' do
      let(:input) { 'R' }

      it 'alters a rovers direction' do
        expect(position_change).to eq robotic_rover.right_turn
      end
    end

    context 'when left command' do
      let(:input) { 'L' }

      it 'alters the rovers direction' do
        expect(position_change).to eq robotic_rover.left_turn
      end
    end
  end
end

更改describe_class.new参数的值

1 个答案: