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删除rspec中的测试-更改(Model,:count)失败-为什么需要重新加载?

rspec testing ruby ruby-on-rails

David Hempy · 技术社区 · 10 年前

TLDR:App.count需要重新加载才能查看创建的记录。为什么?

我找到了很多关于测试DELETE方法的参考资料,如下所示:

expect { delete_request }.to change(App, :count).by(-1)

这是有道理的,在一些类似的场景中也适用。然而,我在测试不应该工作的删除时发现了一个问题,例如当没有用户登录时。

这里是我的开始,有两种方法来测试同一件事:

require 'rails_helper'

RSpec.describe V1::AppsController, type: :controller do
  let(:user) { create(:user) }
  let(:app) { create(:app, account: user.account) }

  describe 'DELETE destroy when you are not logged in' do
    let(:delete_request) { delete :destroy, id: app, format: :json }

    it 'does not delete the app (.count)' do
      expect { delete_request }.not_to change(App, :count)
    end

    it 'does not delete the app (.exists?)' do
      delete_request
      expect(App.exists?(app.id)).to eq(true)
    end
  end
end

这是rspec所说的:

V1::AppsController
  DELETE destroy when you are not logged in
    does not delete the app (.count) (FAILED - 1)
    does not delete the app (.exists?)

Failures:

  1) V1::AppsController DELETE destroy when you are not logged in does not delete the app (.count)
     Failure/Error: expect { delete_request }.not_to change(App, :count)
       expected #count not to have changed, but did change from 0 to 1
     # ./spec/controllers/v1/delete_test_1.rb:11:in `block (3 levels) in <top (required)>'

2 examples, 1 failure

注意最令人困惑的部分: expected #count not to have changed, but did change from 0 to 1 嗯?我试图进行非法删除,我的记录计数生长一个?还要注意,显式检查主题记录仍然有效。

所以我又玩了一些,发现我可以在expect()之前重新加载来解决这个问题:

it 'does not delete the app (.count)' do
  puts "App.count is #{App.count} (after create(:app))"
  app.reload
  puts "App.count is #{App.count} (after reload)"
  expect { delete_request }.not_to change(App, :count)
  puts "App.count is #{App.count} (after request)"
end

现在rspec很高兴:

V1::AppsController
  DELETE destroy when you are not logged in
App.count is 0 (after create(:app))
App.count is 1 (after reload)
App.count is 1 (after request)
    does not delete the app (.count)
    does not delete the app (.exists?)

2 examples, 0 failures

从这一切来看,我决定坚持 exists? 方法但另一个(可能更大的)担忧是,我在互联网络上找到的所有测试样本都是为了测试创建记录,比如 expect { create_request }.to change(App, :count).by(1) 可能是误报,如果他们看到的结果与我相同,并且假设记录是在实际上是缓存工件的情况下创建的?

所以,知道App.count为什么需要 reload 查看当前值?

1 回复 | 直到 10 年前

Rodrigo 10 年前

这是因为当ruby调用 delete_request 方法,它调用 app 方法,并创建一个 App

要对此进行测试,请在调用 expect rspec方法:

it 'does not delete the app (.count)' do
  app #creates the app
  expect { delete_request }.not_to change(App, :count)
end

看看 let 的文档:

使用let定义一个内存化的助手方法。该值将被缓存跨同一示例中的多个调用,但不跨示例。

注意,let是懒求值的 :直到第一次调用它定义的方法的时间。你可以使用let!强制方法的调用。

https://www.relishapp.com/rspec/rspec-core/v/2-11/docs/helper-methods/let-and-let