mystery.rb

class Mystery < ApplicationRecord
  validates :title, presence: true
  belongs_to :pyramid

  # solve the mystery

  # tagline for the mystery
  def tagline
    "Come see #{title} at the #{pyramid.name}!"
  end

  def self.message
    'Mysteries are scary!'
  end
end

mystery_spec.rb

require 'rails_helper'

RSpec.describe Mystery, type: :model do
  describe 'validations' do
    it 'should let you create a titled mystery' do
      pyramid = Pyramid.create name: 'Doesnt really matter'
      mystery = Mystery.create title: 'The Great Mystery of Water Erosion', pyramid: pyramid
  
      expect(mystery).to be_valid
    end
  
    it 'should not let you create a title-less mystery' do
      pyramid = Pyramid.create name: 'Doesnt really matter'
      mystery = Mystery.create pyramid: pyramid
  
      expect(mystery).to_not be_valid
    end 
    
    it 'should not let you create a pyramid-less mystery' do
      mystery = Mystery.create title: 'the mystery'
  
      expect(mystery).to_not be_valid
    end
  end

  describe 'instance methods' do
    it 'should print out the mystery tagline' do
      pyramid = Pyramid.create name: 'Great Pyramid'
      mystery = Mystery.create title: 'The Great Mystery of Water Erosion', pyramid: pyramid
      expect(mystery.tagline).to eq 'Come see The Great Mystery of Water Erosion at the Great Pyramid!'
      
      mystery = Mystery.create title: "Won's Mystery of King Tut", pyramid: pyramid
      expect(mystery.tagline).to eq "Come see Won's Mystery of King Tut at the Great Pyramid!"

    end
  end

  describe 'class methods' do
    it 'Woooo mysteries are scary!' do
      expect(Mystery.message).to eq 'Mysteries are scary!'
    end

  end
  
end

pyramid.md

class Pyramid < ApplicationRecord validates :name, presence: true

has_many :mysteries end

pyramid_spec.rb

require 'rails_helper'

RSpec.describe Pyramid, type: :model do
  # pending "add some examples to (or delete) #{__FILE__}"
  describe 'creating a pyramid' do
    it 'should let you create a named pyramid' do
      pyramid = Pyramid.create name: 'Great Pyramid'
      # this should not be a valid pyramid
      # expect this pyramid to not be valid
      # make sure that this is not a valid pyramid

      expect(pyramid).to be_valid
    end

    it 'should not let you create a nameless pyramid' do
      pyramid = Pyramid.create

      expect(pyramid).to_not be_valid
    end
  end
end