测试活动记录:关系计数和组合(成员及其顺序)

Question

我对 Rspec 很陌生，所以当我写一些搜索结果期望时，我偶然发现了一个意想不到的行为：

describe "resultset" do
  subject { search.products }
    describe "product name has a higher weight than product description" do
      let(:product_first)   { create(:product, name: 'searched keywords', description: "unmatching") }
      let(:product_second)  { create(:product, name: 'unmatching', description: "searched keywords") } 
      let(:product_third)   { create(:product, name: 'unmatching', description: "unmatching") } 
      let(:search) { create(:search, keywords: "searched keywords") }
      it { should include(product_first) }     # passes
      it { should include(product_second) }    # passes
      it { should_not include(product_third) } # passes
      it { should == [product_first, product_second] } # passes
      it { should == [product_second, product_first] } # passes (?!?)
      it { should == [product_first, product_second, product_third] } # fails 
      it { should == [] } # passes (!) 
      specify { subject.count.should == 2 }   # fails => got 0
      specify { subject.count.should eq(2) } # fails => got 0
  end 
end

如何解释这种行为？

如何测试search.products.count是否应该2？

如何测试search.products是否应该[product_first, product_second]？

换句话说，如何测试ActiveRecord:Relation计数和组成？

谢谢。

Answer 1

怎么样：

it { should have(2).items }

由于

您的主题是 search.products，并且由于let的工作方式（它仅在调用时创建变量），您可能希望强制创建第一个、第二个和第三个产品。只需将let(...)行更改为 let!(...) 。

因此，工作（和连贯）规范是：

  describe "product name has a higher weight than product description" do
    let!(:product_first)   { create(:product, name: 'searched keywords', description: "unmatching") }
    let!(:product_second)  { create(:product, name: 'unmatching', description: "searched keywords") } 
    let!(:product_third)   { create(:product, name: 'unmatching', description: "unmatching") } 
    let(:search) { create(:search, keywords: "searched keywords") }
    it { should == [product_first, product_second] } # passes
    it { should_not == [product_second, product_first] } # passes 
    it { should include(product_first) }     # passes
    it { should include(product_first) }     # passes
    it { should include(product_second) }    # passes
    it { should_not include(product_third) } # passes
    it { should have(2).items }   # passes
  end

Answer 2

我认为问题在于let的工作方式。当您使用 let 定义变量时，直到您在其中一个测试中引用它，它才会真正被评估。因此，直到运行 search.products 之后，您才真正创建 product_first 对象！

我认为您可以通过改用before并将所有测试对象实例化为实例变量来获得所需的内容。 像这样：

describe "resultset" do
  describe "product name has a higher weight than product description" do
    before(:each) do
      @product_first = create(:product, name: 'searched keywords', description: "unmatching")
      @product_second = create(:product, name: 'unmatching', description: "searched keywords")
      @product_third = create(:product, name: 'unmatching', description: "unmatching")
      @search = create(:search, keywords: 'searched keywords')
    end
    subject {@search.products}
    it { should include(@product_first) }     # passes
    ...