你如何使用 rspec 模拟依赖方法

Question

我正在尝试为我的黄瓜结果编写一个自定义解析器。为此，我想围绕它编写 rspec 测试。我目前拥有的如下：

describe 'determine_test_results' do
  it 'returns a scenario name as the key of the scenario results, with the scenario_line attached' do
    pcr = ParseCucumberJsonReport.new
    expected_results = {"I can login successfully"=>{"status"=>"passed", "scenario_line"=>4}}
    cucumber_results = JSON.parse(IO.read('example_json_reports/json_passing.json'))
    pcr.determine_test_results(cucumber_results[0]).should == expected_results
  end
end

问题是，determine_test_results 有一个名为determine_step_results 的子方法，这意味着这实际上是两个方法之间的集成测试，而不是determine_test_results 的单元测试。

我将如何模拟来自确定步骤结果的“响应”？

假设 determine_step_results 返回 {"status"=>"passed", "scenario_line"=>4}

我尝试过的：

pcr.stub(:determine_step_results).and_return({"status"=>"passed", "scenario_line"=>6})

和

allow(pcr).to receive(:determine_step_results).and_return({"status"=>"passed", "scenario_line"=>6})

Answer 1

您可以利用存根来完成您想要完成的任务。 Project: RSpec Mocks 2.3 将是关于这个特殊案例的好读物。我在下面添加了一些代码作为建议。

describe 'determine_test_results' do
 it 'returns a scenario name as the key of the scenario results, with the scenario_line       attached' do
   pcr = ParseCucumberJsonReport.new
   expected_results = {"I can login successfully"=>{"status"=>"passed", "scenario_line"=>4}}

   # calls on pcr will return expected results every time determine_step_results is called in any method on your pcr object.
   pcr.stub!(:determine_step_results).and_return(expected_results)

   cucumber_results = JSON.parse(IO.read('example_json_reports/json_passing.json'))
   pcr.determine_test_results(cucumber_results[0]).should == expected_results
 end
end

Answer 2

如果determine_test_results 所做的只是调用determine_step_results，你不应该真正测试它，因为它是微不足道的......

如果你决定测试它，你只需要测试它是否调用了委托函数，并返回 whatever 传递给它：

describe ParseCucumberJsonReport do
  describe '#determine_test_results' do
    it 'calls determine_step_results' do
      result = double(:result)
      input = double(:input)
      expect(subject).to receive(:determine_step_results).with(input).and_return(result)

      subject.determine_test_results(input).should == result
    end
  end
end

如果它正在做更多事情（例如将结果添加到更大的哈希中），您也可以描述它：

describe ParseCucumberJsonReport do
  describe '#determine_test_results' do
    it 'calls determine_step_results' do
      result = double(:result)
      input = double(:input)
      expect(subject).to receive(:determine_step_results).with(input).and_return(result)
      expect(subject.larger_hash).to receive(:merge).with(result)

      subject.determine_test_results(input).should == result
    end
  end
end