model_spec_starter.rb

require 'rails_helper'

RSpec.describe Model, type: :model do 
  describe 'Validations' do
    it 'it is invalid without ___' do
      expect(Model.new(some_attr: nil)).to_not be_valid
    end
	  
    it 'it validates presence of some_attr' do
      expect(Model.new(some_attr: nil)).to validate_presence_of(:some_attr)
    end
  end 

  xcontext "Class Methods" do
    it "some class method here" do
      #create some instances of Model
      expected = "some anticipated result"
      expect(Model.class_method()).to eq(expected)
    end
  end 
	
  xcontext "Instance Methods" do
    it "some instance method here" do
      instance = Model.create() #create an instance of Model
      expected = "some anticipated result"
      expect(instance.instance_method()).to eq(expected)
    end
  end 
end

# Can also do it this way:
require 'rails_helper'

describe Customer do
  describe "Validations" do
    it {is_expected.to validate_presence_of(:first_name)}
    it {is_expected.to validate_presence_of(:last_name)}
    it {is_expected.to validate_presence_of(:created_at)}
    it {is_expected.to validate_presence_of(:updated_at)}
  end

  describe "Relationships" do
    it {is_expected.to have_many(:invoices)}
    it {is_expected.to have_many(:merchants).through(:invoices)}
  end

end

-----------------
(for testing anything else like a service or query...)
	
require 'rails_helper'

RSpec.describe MakeProjectResourcesService do
  describe 'Methods' do
    it 'does stuff' do 
    end 
  end 
end