ruby-on-rails - FactoryGirl after_create 方法不保存

Question

我有一个简单的情境设置，以便学习使用 FactoryGirl 进行测试。 银行有很多交易。每次创建交易时，它都应该从银行的总额中减去交易金额。

代码如下:

# Bank.rb - Has many transactions
class Bank < ActiveRecord::Base
  has_many :transactions
end


# Transaction.rb - Belongs to a bank and should decrement the bank's total when created.
class Transaction < ActiveRecord::Base
  belongs_to :bank
  after_create :decrement_bank_amount

  def decrement_bank_amount
    bank.decrement!(:amount, amount) if bank
  end
end


# factories.rb - Create default factories for testing. This is FactoryGirl 4 syntax
FactoryGirl.define do
  factory :bank do
    sequence(:name) { |n| 'Bank ' + n.to_s }
  end

  factory :transaction do
    sequence(:title) { |n| 'Payment ' + n.to_s }
    bank
  end
end


# Transaction_spec.rb - Creates a bank and a transaction.
require 'spec_helper'

describe Transaction do
  describe ".create" do
    context "when a bank is set" do
      it "decreases the bank's amount" do
        bank = FactoryGirl.create(:bank, :amount => 1000) do |b|
          b.transactions.create(:amount => 250)
        end

        bank.amount.to_i.should eq 750
      end
    end
  end
end

测试一直失败，银行金额一直返回 1000 而不是预期的 750。我很难过!

Answer 1

此测试失败，因为 bank 是从数据库中提取并存储的。 after_create 回调修改数据库中的记录，但 bank 中的对象看不到它，因此不会更新。

在检查金额之前，您需要对该对象调用reload:

bank.reload
bank.amount.to_i.should == 750