ruby-on-rails - RSPEC - 预期错误与接收错误

Question

这是我的测试:

describe Item do
  subject {Item.new(:report_id => 26 ,  :name => 'Gas' ,  :tax_rate => 0.13, :tax_id => 1 ,  :category_id => 15 ,  :sub_category_id => 31 ,  :job_id => 1 , :total => 20 )}

  let(:tax) {Tax.where(id: subject.tax_id).first}
  let(:sub_category) {SubCategory.where(id: subject.sub_category_id).first}


  it 'Calculate with just Total' do

    subject.name.should be == 'Gas'
    tax = Tax.find_by_id(subject.tax_id)
    subject.sub_category_id.should be == 31
    subject.set_nil_values
    sub_category.should_receive(:taxable).and_return(1)
    tax.should_receive(:rate).and_return(0.13)
    sub_category.should_receive(:tax_adjustment).and_return(nil)
    subject.should_receive(:tax_rate).and_return(0.13)
    subject.calculate_tax(tax, sub_category)
    subject.tax_amount = (((subject.total - subject.deduction) - ((subject.total - subject.deduction) / (1 + 0.13))) * 1)
    subject.calculate_cost
    subject.cost.should be_within(0.01).of(17.70)

  end

这是我的错误:

  1) Item Calculate with just Total
     Failure/Error: subject.should_receive(:tax_rate).and_return(0.13)
       (#<Item:0x007faab7299c30>).tax_rate(any args)
           expected: 1 time with any arguments
           received: 3 times with any arguments
     # ./spec/models/item_spec.rb:25:in `block (2 levels) in <top (required)>'

我做了一些研究，并尝试改用它:

    expect_any_instance_of(subject).to receive(:tax_rate)

但是现在出现如下错误:

  1) Item Calculate with just Total
     Failure/Error: expect_any_instance_of(subject).to receive(:tax_rate)
     NoMethodError:
       undefined method `method_defined?' for #<Item:0x007fe6fdaa1bf8>
     # ./spec/models/item_spec.rb:25:in `block (2 levels) in <top (required)>'

Answer 1

您最初的错误发生是因为，如错误消息所述，所讨论的方法被调用了三次而不是一次，这是隐含的期望。假设实际行为是应该的，您可以将期望更改为:

...receive(...).exactly(3).times

参见 http://rubydoc.info/gems/rspec-mocks/frames了解更多信息。

至于您遇到的第二个错误，根据我的测试，当您将 expect_any_instance_of 与一个已经 stub 实例的类一起使用，然后调用该 stub 实例时，就会发生这种情况。无论如何，即使这行得通，我也不相信这是您想要的，因为 expect_any_instance_of 的频率语义与 expect 相同，即“跨 stub 实例的一个(总)调用”。

如果第二个错误发生时您没有删除对 subject 的现有期望，请告诉我。