如何在 Rails 5 中使用 RSpec 测试模型中的关联？

Question

我是 Rails 5 的新手，正在尝试测试一个极其简单的数据库模型，但我似乎无法做到正确。我正在尝试测试has_many 关联。

模型代码如下：

app/models/database_models/response.rb

module DatabaseModels
  class Response < ApplicationRecord

    has_many :question_responses, :class_name => 'DatabaseModels::
QuestionResponse'

  end
end

规范（RSpec）看起来像这样

spec/models/screener_response_spec.rb

require 'rails_helper'

describe DatabaseModels::Response, type: :model do
  it { is_expected.to have_many(:question_responses) }
end

它失败了：

expected #<DatabaseModels::Response:0x007fd91ccda210> to respond to `has_many?`

我做错了什么？

Answer 1

一种测试方法是测试实际行为：

require 'rails_helper'

describe DatabaseModels::Response, type: :model do

  let(:response) { described_class.new }
  it 'has many question responses' do
    expect( response.question_responses.new ).to be_a_new DatabaseModels::
QuestionResponse 
  end
end

否则你可以使用反射，这基本上是 shoulda 所做的：

require 'rails_helper'

describe DatabaseModels::Response, type: :model do
  it 'has many question responses' do
    relation = described_class.reflect_on_association(:question_resp‌​onses)
    expect(relation.macro).to eq :has_many
  end
end