rspec - 如何在 ruby​​ 中測試零輸入

Question

我正在嘗試編寫一個規范來測試當用戶只是按下“Enter”鍵時我的代碼將如何反應，即不輸入任何數據只是按下“Enter”。

代碼本身將循環，直到創建有效條目，但我無法獲得規范來對其進行測試。 下面的代碼是類和規范的示例。

請注意，在規范中，我嘗試用 with_input('') 替換“重復詢問”部分，但它似乎掛起（或循環）

class Example
  def initialize(input: $stdin, output: $stdout)
    @input = input
    @output = output
  end

  def ask_for_number
    @output.puts "Input an integer 5 or above"
    loop do
      input = @input.gets.to_i
      return true if input >= 5
      @output.puts "Invalid. Try again:"
    end
  end
end

--- 和規格

require 'stringio'
require_relative 'Example' 
describe Example do
  context 'with input greater than 5' do
    it 'asks for input only once' do
      output = ask_for_number_with_input(6)

      expect(output).to eq "Input an integer 5 or above\n"
    end
  end

  context 'with input equal to 5' do
    it 'asks for input only once' do
      output = ask_for_number_with_input('5')

      expect(output).to eq "Input an integer 5 or above\n"
    end
  end

  context 'with input less than 5' do
    it 'asks repeatedly, until a number 5 or greater is provided' do
      output = ask_for_number_with_input(2, 3, 6)

      expect(output).to eq <<~OUTPUT
        Input an integer 5 or above
        Invalid. Try again:
        Invalid. Try again:
      OUTPUT
    end
  end

  def ask_for_number_with_input(*input_numbers)
    input = StringIO.new(input_numbers.join("\n"))
    output = StringIO.new

    example = Example.new(input: input, output: output)
    expect(example.ask_for_number).to be true

    output.string
  end
end

Answer 1

當你用它替換它時

output = ask_for_number_with_input("")

它永遠循環，因為這就是你的代碼告訴它做的，你希望它循環直到它收到一個大於 6 的數字，這永遠不會發生， @input.gets.to_i將繼續返回0因為IO#gets

如果在文件末尾調用，則返回 nil。

要讓它停止掛起，只需給它另一個值：

it 'asks repeatedly, until a number 5 or greater is provided' do
  output = ask_for_number_with_input("", "", 6)

  expect(output).to eq <<~OUTPUT
    Input an integer 5 or above
    Invalid. Try again:
    Invalid. Try again:
  OUTPUT
end

現在它過去了

Answer 2

只需模仿循環：

require "spec_helper"

describe 'Example' do
  let(:entered_value) { 6 }
  let(:stdin) { double('stdin', gets: entered_value) }
  let(:stdout) { double('stdout') }
  subject { Example.new(input: stdin, output: stdout) }

  describe '#ask_for_number' do
    before(:each) do
      allow(subject).to receive(:loop).and_yield
    end

    context 'pressed enter without any input' do
      let(:entered_value) { nil }


      it 'prints invalid output' do
        expect(stdout).to receive(:puts).with("Input an integer 5 or above")
        expect(stdout).to receive(:puts).with("Invalid. Try again:")

        subject.ask_for_number
      end
    end
  end
end