rspec模型测试；方法无效

Question

该方法本身正常工作，但是当我试图在模型规范中测试它时，create部件失败了。找到的部分很好用。我错过了什么？

conversation.rb

scope :between, -> (sender_id, recipient_id) do
  where("(conversations.sender_id = ? AND conversations.recipient_id = ?) OR (conversations.sender_id = ? AND conversations.recipient_id = ?)", sender_id, recipient_id, recipient_id, sender_id)
end

def self.create_or_find_conversation(task_assigner_id, task_executor_id)
  Conversation.between(task_assigner_id, task_executor_id).first_or_create do |conversation|
    conversation.sender_id = task_assigner_id
    conversation.recipient_id = task_executor_id
  end
end

conversation_spec.rb

describe "class methods" do

  let(:sender) { create(:user) }
  let(:recipient) { create(:user) }
  let(:other_recipient) { create(:user) }
  let!(:conversation) { create(:conversation, sender: sender, recipient: recipient) }

  context "create_of_find_conversation" do

   #this one throws Failure/Error: expect{conv}.to change{Conversation.count}.by(1)
   #expected result to have changed by 1, but was changed by 0
    it "creates conversation" do
      conv = Conversation.create_or_find_conversation(sender, other_recipient)
      expect{conv}.to change{Conversation.count}.by(1)
    end

    #this one is working as expected
    it "finds conversation" do
      conv = Conversation.create_or_find_conversation(sender, recipient)
      expect(conv).to eq(conversation)
    end
  end
end

Answer 1

我认为这些代码：

it "creates conversation" do
  conv = Conversation.create_or_find_conversation(sender, other_recipient)
  expect{conv}.to change{Conversation.count}.by(1)
end

应改为：

it "creates conversation" do
  expect{
      Conversation.create_or_find_conversation(sender.id, other_recipient.id)
  }.to change{Conversation.count}.by(1)
end

因为它不是值改变了计数，而是进程。

Answer 2

Ruby中的正则变量不是延迟加载--在分配变量时，分配的右侧将被处理。

def do_something(val)
  puts "do_something called"
  val
end

a = do_something(hello_world)
puts a
# do_something called
# hello world

您要么需要更改期望，以便在传递的块中调用该操作以期望：

it "creates conversation" do
  expect do
    Conversation.create_or_find_conversation(sender, other_recipient)
  end.to change{Conversation.count}.by(1)
end

或者使用RSpec的let创建一个延迟加载变量：

let(:conv) { Conversation.create_or_find_conversation(sender, other_recipient) }

it "creates conversation" do
  expect { conv }.to change{Conversation.count}.by(1)
end

但这并不能解决您对域建模错误的根本问题。在一次谈话中，双方轮流交谈--所以使用recipient_id和sender_id是完全错误的。相反，它的消息有发送方和接收方。

您可以将它们更改为任意名称，但是使用适当的多到多关系要简单得多，这样就不需要复杂的AND OR查询了。

class User < ActiveRecord::Base
  has_many :user_conversations
  has_many :conversations, through: user_conversations
end

class Conversation < ActiveRecord::Base
  has_many :user_conversations
  has_many :users, through: user_conversations
end

# the m2m join model.
class UserCoversation < ActiveRecord::Base
  belongs_to :user
  belongs_to :conversation
end

然后，您可以简单地查询：

Conversation.where(users: [a, b])