使用 Rspec let 测试失败答案

【问题标题】：Test with Rspec let is failing使用 Rspec let 测试失败
【发布时间】：2014-09-26 10:10:43
【问题描述】：

我对 FactoryGirl 和 RSpec 有疑问。我有以下测试：

require 'rails_helper'
describe Customer do
  it_behaves_like "Account"

  describe "it has an address" do
    let(:customer) {create(:customer)}
    let(:address) {create(:address, addressable_id: customer.id, addressable_type: "Account")}

    it "should have an address" do
      expect(customer.address).to eq address
    end
  end
end

当我尝试运行时，它会抛出以下错误：

) Customer it has an address should have an address
     Failure/Error: expect(customer.address).to eq address

       expected: #<Address id: 1, street: "Street 1", zip_code: "11-111", city: "City 1", addressable_id: 1, addressable_type: "Account", created_at: "2014-09-26 10:07:51", updated_at: "2014-09-26 10:07:51">
            got: nil

       (compared using ==)
     # ./spec/models/customer_spec.rb:11:in `block (3 levels) in <top (required)>'

但是当我把它重构成这样的时候：

require 'rails_helper'

describe Customer do
  it_behaves_like "Account"

  describe "it has an address" do
    before do
      @customer = create(:customer)
      @address = create(:address, addressable_id: @customer.id, addressable_type: "Account")
    end

    it "should have an address" do
      expect(@customer.address).to eq @address
    end
  end
end

它工作正常。为什么我的 let 示例失败了？

【问题讨论】：

标签： ruby-on-rails ruby rspec factory-bot

【解决方案1】：

那是因为 let 被延迟评估。

调用 expect(customer.address) 会调用您的第一个 let 块，即 create(:customer) 。它返回一个没有地址的customer。

在调用eq address 之前，不会调用第二个let 块create(:address, ...)。

您可以使用let! 立即创建地址：

let!(:address) { create(:address, ...) }

另一种选择是使用自定义工厂customer_with_address 来设置association。

【讨论】：