Add RSpec Test Quiz Model Validations
user
```ruby
require 'rails_helper'

RSpec.describe Quiz, type: :model do
  def valid_attributes(new_attributes = {})
    attributes = {
      title: "Super Fly",
      body: "The CodeCore Q quiz app",
      level: 99,
      category_id: 5
    }
    attributes.merge(new_attributes)
  end

  describe "Validations" do
    it "requires a title" do
      quiz = Quiz.create(valid_attributes({title: nil}))
      expect(quiz).to be_invalid
    end

    it "requires a unique title" do
      quiz   = Quiz.create(valid_attributes)
      quiz_1 = Quiz.create(valid_attributes)
      expect(quiz_1).to be_invalid
    end

    it "requires a body" do
      quiz = Quiz.create(valid_attributes({body: nil}))
      expect(quiz).to be_invalid
    end

    it "requires a level" do
      quiz = Quiz.create(valid_attributes({level: nil}))
      expect(quiz).to be_invalid
    end

    it "requires a level to be a integer, not a string" do
      quiz = Quiz.create(valid_attributes({level: "YAR"}))
      expect(quiz).to be_invalid
    end

    it "will create a quiz with the level as a integer" do
      quiz = Quiz.create(valid_attributes({level: 88}))
      expect(quiz).to be_valid
    end

    it "requires a category_id" do
      quiz = Quiz.create(valid_attributes({category_id: nil}))
      expect(quiz).to be_invalid
    end

    it "requires a category_id to be a integer, not a string" do
      quiz = Quiz.create(valid_attributes({category_id: "Blooper"}))
      expect(quiz).to be_invalid
    end

    it "will create a quiz with the category_id as a integer" do
      quiz = Quiz.create(valid_attributes({category_id: 22}))
      expect(quiz).to be_valid
    end
  end
end
```
assistant