humanizable.rb

module Humanizable
  attr_accessor :name
end

humanizable_spec.rb

require 'spec_helper.rb'

class HumanizableUnit
  include Humanizable
end

describe Humanizable do
  subject { HumanizableUnit.new }
  
  describe 'attribute accessors' do
    it 'should have a name' do
      subject.name = 'Alice'
      expect(subject.name).to eq('Alice')
    end
  end
end

person.rb

class Person
end

person_spec.rb

require 'spec_helper.rb'

describe Person do
  it_behaves_like Humanizable
end