RSpec Helpers

presence.rb

# In spec/support/presence.rb
RSpec.shared_examples 'presence' do |attrs|
  describe 'presence validations' do
    attrs.each do |attr|
      it "checks presence of #{attr}" do
        target = described_class.name.downcase.to_sym
        obj = FactoryGirl.build target, attr.to_sym => nil
        expect(obj.valid?).to eq false
        expect(obj.errors[attr.to_sym].size).to eq 1
      end
    end
  end
end

spec_helper.rb

# Load the support files
Dir["./spec/support/**/*.rb"].sort.each { |f| require f}

uniqueness.rb

# In spec/support/uniqueness.rb
RSpec.shared_examples 'uniqueness' do |objects|
  describe 'uniqueness validations' do
    objects.each do |attr, creator|
      it "checks uniqueness of #{attr}" do
        new_value = creator.call
        expect(new_value).to_not eq nil

        target = described_class.name.downcase.to_sym

        obj = FactoryGirl.build target
        obj.send("#{attr}=", new_value)
        expect(obj.save).to eq true

        obj2 = FactoryGirl.build target
        obj2.send("#{attr}=", new_value)
        expect(obj2.valid?).to be false
        expect(obj2.errors[attr.to_sym].size).to eq 1
      end
    end
  end
end

user_spec.rb

require 'rails_helper'

RSpec.describe User, type: :model do
  include_examples 'presence', %w(email)
  include_examples 'uniqueness', {
    email: -> { Faker::Internet.email }
  }
end