在上一篇我們已經安裝好 rspec 也產出了 User model 接下來就開始嘗試寫測試摟！

我在 User 上多了幾個欄位接下來就可以針對以下欄位來做測試

2.6.6 :003 > User
 => User(id: integer, created_at: datetime, updated_at: datetime,
         name: string, email: string, phone: integer)

Rspec 基本架構

我們可以先思考 name 這個欄位為必填的話測試可以怎麼寫？

require 'rails_helper'

RSpec.describe User, type: :model do
  describe 'validations' do
    context 'name must be present' do
      it 'is not valid without a name' do
        user = User.new(phone: '123', email: 'test@ck.com')
        expect(user).not_to be_valid
      end

      it 'is valid with a name' do
        user = User.new(name: 'ck', phone: '123', email: 'test@ck.com')
        expect(user).to be_valid
        expect(user.name).to eq('ck')
      end
    end
  end
end

用上述例子可以看到有很多陌生的專有名詞，我們可以依依解釋

type: :model => 指定type 為 model，當然也有 controller、view、request
describe => 就是字面上的意思描述此區域的測試要測的內容
context => 作用域其實與 describe 相同其實沒有太多差異只是describe的別名，主要是區隔規格
it => 指每個測試案例
expect => 最常用到的語法也是每個測試的精髓，你期望哪些東西會等同於你想像的樣子。比如：沒有名字那就期望這個user在建立時就是無效的

對於describe與context差異的朋友可以看看這篇 describe vs. context in rspec

According to the rspec source code, “context” is just a alias method of “describe”, meaning that there is no functional difference between these two methods. However, there is a contextual difference that’ll help to make your tests more understandable by using both of them.

如果我們跑一下這個測試會發現測試沒有通過

$ rspec spec/models/user_spec.rb

Failures:

  1) User validations name must be present is not valid without a name
     Failure/Error: expect(user).not_to be_valid
       expected #<User id: nil, created_at: nil, updated_at: nil, name: nil, email: "test@ck.com", phone: 123> not to be valid
     # ./spec/models/user_spec.rb:8:in `block (4 levels) in <top (required)>'

Finished in 0.12145 seconds (files took 4.03 seconds to load)
2 examples, 1 failure

Failed examples:

rspec ./spec/models/user_spec.rb:6 # User validations name must be present is not valid without a name

當 user 沒有 name 時應該要是無效的但他卻建立出來了
這時就會知道應該是在 model 的地方沒有補上 validate 導致測試沒通過所以我們到 models/user.rb

# user.rb
class User < ApplicationRecord
  validates :name, presence: true
end

再跑一次測試 rspec spec/models/user_spec.rb

$ rspec spec/models/user_spec.rb
..

Finished in 0.12003 seconds (files took 4.19 seconds to load)
2 examples, 0 failures

我們第一個測試就大功告成了！ 但也會發現怎麼建立起來這麼麻煩而且有重複的code 明天我們就使用 Shoulda Matchers 跟 FactoryBot 來優化測試吧！