使用 RSpec 撰寫 Unit Tests

我們可以使用單元測試來檢查模型的屬性和自定方法是否正常運作; 假設有個 Category model，內容如下

class Category < ActiveRecord::Base
  has_many :videos, -> { order('created_at DESC') }

  validates :name, presence: true, uniqueness: true

  def recent_videos
    videos.first(6)
  end

end

那麼對應的測試程式 spec/models/category_spec.rb 其內容可以撰寫如下

require 'spec_helper'
require 'shoulda/matchers'

describe Category do

  it { is_expected.to have_many :videos }
  it { is_expected.to validate_presence_of :name }
  it { is_expected.to validate_uniqueness_of :name }

  describe "#recent_videos" do
    let(:category) { Category.create!(name: "Game")}
    subject { category.recent_videos }

    it "returns an empty array if the category does not have any videos" do
      expect(subject).to eq []
    end

    it "returns all videos if there are less than 6 videos" do
      1.upto(5) { |index|  category.videos.create(
        title: "FF#{index}", description: "Final Fantasy") }
      expect(subject.count).to eq 5
    end

    it "returns 6 videos if there are more than 6 videos" do
      1.upto(7) { |index| category.videos.create(
        title: "FF#{index}", description: "Final Fantasy") }
      expect(subject.count).to eq 6
    end

    it "returns the videos in the reverse order by created_at" do
      ff = category.videos.create(
        title: "FF", description: "Final Fantasy", created_at: 2.days.ago)
      dq = category.videos.create(
        title: "DQ", description: "Dragon Quest", created_at: 1.day.ago)
      expect(subject).to eq [dq, ff]
    end

  end

end

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使用 RSpec 撰寫 Unit Tests

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