在每次测试后更改rspec instance_double返回值

Question

我正在用Rspec测试一个Ruby类。我希望在这两个上下文之间更改实例double的返回值，即，我希望tallied_data.a_conv、tallied_data.a_nonconv等为"when A is winner“上下文返回不同的值。有没有什么方法可以做到这一点，而不必创建新的instance_double并重复第3-9行中的所有代码？有没有不同的方法来解决这个问题？

describe ABSplitTest do
  describe "#test_winner" do
  let(:tallied_data) do
    instance_double("ABDataSummary", 
      a_conv: 50, a_nonconv: 51, 
      b_conv: 52, b_nonconv: 53,
      to_h: { a: { conv: 50, nonconv: 51 }, b: { conv:52, nonconv: 53 } }
    )
  end
  subject(:sample_test) { ABSplitTest.new(tallied_data) }

  context "when there is no winner" do
    it "returns that there is no clear winner" do
      expect(sample_test.test_winner).to \
        eq("No winner at 0.05 significance")
    end
  end

  context "when A is winner" do
    it "returns that A is winner" do
      expect(sample_test.test_winner).to \
        eq("No winner at 0.05 significance")
    end
  end

Answer 1

不太清楚您在测试中做了什么，以及它与tallied_data有何关系，但您可以通过let在您的上下文中设置特定值。let值直到第一次使用时才会被解析，因此如果需要，您可以根据内部上下文中的值来组合它们。

例如：

describe ABSplitTest do
  describe "#test_winner" do
    let(:tallied_data) do
      instance_double("ABDataSummary",
        a_conv: a_conv, a_nonconv: 51,
        b_conv: 52, b_nonconv: 53,
        to_h: { a: { conv: 50, nonconv: 51 }, b: { conv:52, nonconv: 53 } }
      )
    end
    subject(:sample_test) { ABSplitTest.new(tallied_data) }

    context "when there is no winner" do
      let(:a_conv) { 50 }
      it "returns that there is no clear winner" do
        expect(sample_test.test_winner).to \
          eq("No winner at 0.05 significance")
      end
    end

    context "when A is winner" do
      let(:a_conv) { 70 }
      it "returns that A is winner" do
        expect(sample_test.test_winner).to \
          eq("No winner at 0.05 significance")
      end
    end