Day05 测试写起乃 - Shoulda Matchers

昨天我们已经写出了第一篇测试 今天我们就要来依靠 Shoulda Matchers 来简化以及优化我们的测试

安装 Shoulda Matchers

Shoulda Matchers github

group :test do
  gem 'shoulda-matchers', '~> 5.0'
end

然後跑 bundle install

他也告诉你他帮你多了好几种 matchers 在官方文件上都查得到
将以下 code 放到 spec/rails_helper.rb

Shoulda::Matchers.configure do |config|
  config.integrate do |with|
    with.test_framework :rspec
    with.library :rails
  end
end

在底下也有告诉你基础运用

# RSpec
RSpec.describe MenuItem, type: :model do
  describe 'associations' do
    it { should belong_to(:category).class_name('MenuCategory') }
    # 测试关联性
  end

  describe 'validations' do
    it { should validate_presence_of(:name) }
    # 测试是否为必填
    it { should validate_uniqueness_of(:name).scoped_to(:category_id) }
    # 测试是否是唯一值
  end
end

应用 Shoulda Matchers

我们就来优化一下昨天写的测试吧！

require 'rails_helper'

RSpec.describe User, type: :model do
  describe 'validations' do
    context 'name must be present' do
      it { should validate_presence_of(:name) }
      # 等同於
      # subject.should validate_presence_of(:name)
      # it { is_expected.to validate_presence_of(:name) }
    end
  end
end

这行就可以直接拿来测 name 是不是有限制要必填，刚刚写了这麽多但 Shoulda Matchers 一行就帮你搞定！

我们可以试着把 validates :name, presence: true 拔掉跑一次测试不会过

$ rspec spec/models/user_spec.rb
F

Failures:

  1) User validations name must be present is expected to validate that :name cannot be empty/falsy
     Failure/Error: it { should validate_presence_of(:name) }

       Expected User to validate that :name cannot be empty/falsy, but this
       could not be proved.
         After setting :name to ‹""›, the matcher expected the User to be
         invalid, but it was valid instead.
     # ./spec/models/user_spec.rb:6:in `block (4 levels) in <top (required)>'

Finished in 0.06186 seconds (files took 2.86 seconds to load)
1 example, 1 failure

再放回去测试就会通过搂！

$ rspec spec/models/user_spec.rb
.

Finished in 0.0644 seconds (files took 3.86 seconds to load)
1 example, 0 failures

Shoulda Matchers 最主要是拿来测试 model 关联性以及验证 可以节省很多 code，其实还有很多语法可以使用在这边就不多赘述了官方文件写的挺详细的！

Should vs is_expected.to

在官方也有提及这两种是否有差别，答案是没有。只是现在更流行使用expect 在 betterspec也有说到目前主流使用expect

明天先来介绍 before、after！再来讲 let、let!、subject！