rspec model test failing

Question

I am writing an app to help me keep track of my social media advertising budgets. When you enter a new advert it should calculate and update the amount spent on the budget it is drawing from. Here is my model that achieves that.

class Advert < ActiveRecord::Base
    belongs_to :budget
  before_save :update_budget
    after_destroy :update_budget

    validates :budget_id, :name, :platform, :ad_type, :amount, :start_date, :end_date, presence: true
    validates :amount, numericality: true
  validate :check_budget

      # Checks to see if there is enough budget remaining to set up advert
      def check_budget
      if self.amount > self.budget.amount_remaining
        errors.add(:amount, " cannot exceed amount remaining in budget.")
      end
    end



    # Updates the amount remaining in the budget on advert save.
    def update_budget
        budget = Budget.find(self.budget_id)
        @adverts = Advert.all
        total_spent = self.amount
        @adverts.each do |advert|
            if advert.budget_id == self.budget_id
                total_spent += advert.amount
            end
        end
        budget.amount_spent = total_spent
        budget.save
    end
end 

This all works but I am currently teaching myself to write tests so I thought I would write a test in rspec for it.

require 'rails_helper'

describe Advert do
    it "updates budget before save" do
        advert = create(:advert)
        budget = advert.budget

        expect(budget.amount_spent).to eq(advert.amount)
        expect(budget.amount_remaining).to eq(budget.amount - budget.amount_spent)
    end

end

However, this test if failing but I cannot figure out why. Here is the error code.

1) Advert updates budget before save
     Failure/Error: expect(budget.amount_spent).to eq(advert.amount)

       expected: 7.0 (#<BigDecimal:7ffa61358b18,'0.7E1',9(18)>)
            got: 0.0 (#<BigDecimal:7ffa6026a9a0,'0.0',9(18)>)

       (compared using ==)
     # ./spec/models/advert_spec.rb:27:in `block (2 levels) in <top (required)>'

And here is the relevant test log.

  SQL (0.3ms)  INSERT INTO "budgets" ("name", "amount", "client_id", "amount_remaining", "created_at", "updated_at") VALUES ($1, $2, $3, $4, $5, $6) RETURNING "id"  [["name", "eos"], ["amount", "432.0"], ["client_id", 102], ["amount_remaining", "432.0"], ["created_at", "2016-03-12 18:08:54.607999"], ["updated_at", "2016-03-12 18:08:54.607999"]]
   (0.1ms)  RELEASE SAVEPOINT active_record_1
   (0.2ms)  SAVEPOINT active_record_1
  Budget Load (0.4ms)  SELECT  "budgets".* FROM "budgets" WHERE "budgets"."id" = $1 LIMIT 1  [["id", 49]]
  Advert Load (0.5ms)  SELECT "adverts".* FROM "adverts"
  SQL (0.4ms)  UPDATE "budgets" SET "amount_spent" = $1, "amount_remaining" = $2, "updated_at" = $3 WHERE "budgets"."id" = $4  [["amount_spent", "7.0"], ["amount_remaining", "425.0"], ["updated_at", "2016-03-12 18:08:54.616491"], ["id", 49]]
  SQL (0.4ms)  INSERT INTO "adverts" ("budget_id", "name", "platform", "ad_type", "amount", "start_date", "end_date", "created_at", "updated_at") VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9) RETURNING "id"  [["budget_id", 49], ["name", "ut"], ["platform", "voluptate"], ["ad_type", "facere"], ["amount", "7.0"], ["start_date", "2016-03-01"], ["end_date", "2016-04-12"], ["created_at", "2016-03-12 18:08:54.619698"], ["updated_at", "2016-03-12 18:08:54.619698"]]
   (0.2ms)  RELEASE SAVEPOINT active_record_1
   (0.2ms)  ROLLBACK

Interestingly if I comment out the first 'expect' the test passes. It's as though it cannot access advert.amount so set's it as 0.

Anyone have any ideas?

Answer 1

This solved my issue.

describe Advert do
    it "updates budget before save" do
        advert = build(:advert)
        budget = advert.budget

        expect(budget.amount_spent).to eq(0)

        advert.save
        budget.reload

        expect(budget.amount_spent).to eq(advert.amount)
        expect(budget.amount_remaining).to eq(budget.amount - budget.amount_spent)
end

I think the source of my problem was not reloading my budget which meant that I was trying to access the attribute before it had been updated.