ruby-on-rails - 平均评级法的 Rspec 模型测试

Question

我正在尝试为以下方法编写测试:

def average_rating
  reviews = self.reviews
  review_sum = reviews.inject(0) { |sum, review| sum += review.rating }
  avg_rating = (review_sum / reviews.count).to_i unless review_sum == 0
end

这是我目前所拥有的:

describe "#average_rating" do
it "should be nil when there are no reviews" do
  api_without_reviews = Api.new name: 'Fake API', description: 'It does something', category: 'Fake category', url: 'http://www.example.com'
  api_without_reviews.average_rating.should be_nil
end
it "should calculate average rating properly" do
  api_with_reviews = Api.new name: 'Fake API', description: 'It does something', category: 'Fake category', url: 'http://www.example.com'
  api_with_reviews.save
  api_with_reviews.reviews.create rating: Random.rand(1..5), thoughts: 'blah'
  api_with_reviews.reviews.create rating: Random.rand(1..5), thoughts: 'blah'
  average = api_with_reviews.reviews.inject(0) { |sum, review| sum += review.rating } / api_with_reviews.reviews.count
  api_with_reviews.average_rating.should eq average
end

结束

如何测试 review_sum 变量是否正确计算总和，或者该方法是否已经过全面测试？我是 rspec 的新手，非常感谢您的帮助!

Answer 1

要直接回答我建议你不要:

• 生成评论评分的随机值
• 直接复制方法代码进行验证。你不能给自己的论文打分，不是吗？

相反:

• 使用手动创建的评分并手动计算平均值
• 验证该方法是否可以输出您计算的结果。

进一步改进

• 使用 FactoryGirl 创建测试对象。<​​/li>
• 擦干代码

我的版本(假设安装了 FactoryGirl)

describe "API" do
  describe "average_rating" do
    # Use "before" but not "let" because this var must be clean in every example
    before { @api = FactoryGirl.create(:api) }
  
    it "should be nil when there are no reviews" do
      @api.average_rating.should be_nil
    end

    it "should calculate average rating properly" do
      [1, 5].each do |r|
        FactoryGirl.create(:review, rating: r, api: @api)
      end 
      @api.average_rating.should eq(3)
    end
  end
end

# spec/factories.rb
FactoryGirl.define do
  factory :api do
    name 'Fake API'
    description 'It does something'
    category 'Fake category'
    url 'http://www.example.com'
  end

  factory :review do
    rating rand(1..5)
    thoughts "blah"
    api   #Association: belongs_to API
  end
end