equaty.rb

class Employee
  attr_reader :id
  attr_reader :name

  def initialize(id, name)
    @id = id
    @name = name
  end
end

class User
  attr_reader :id
  attr_reader :name

  def initialize(id, name)
    @id = id
    @name = name
  end
end

module Operator
  class Equals
    def initialize(x)
      @x = x
    end

    attr_reader :x

    def ==(other)
      return false unless self.class == other.class && self.x.class == other.x.class

      case x
      when Employee then EmployeeMatcher.new(x, other.x).compare!
      when User then UserMatcher.new(x, other.x).compare!
      else
        @x.id == other.x.id
      end
    end
  end

  class EmployeeMatcher
    def initialize(x, y)
      @x = x
      @y = y
    end

    def compare!
      @x.id == @y.id
    end
  end

  class UserMatcher
    def initialize(x, y)
      @x = x
      @y = y
    end

    def compare!
      @x.name == @y.name
    end
  end
end

# Me guiei por: https://shopify.engineering/implementing-equality-in-ruby

employee1 = Employee.new(1, 'Gil')
employee2 = Employee.new(2, 'Gomes')
user1 = User.new(1, 'Gil')
user2 = User.new(1, 'Gil')

a = Operator::Equals.new(employee1)
b = Operator::Equals.new(employee2)
c = Operator::Equals.new(1)
d = Operator::Equals.new(user1)
e = Operator::Equals.new(user2)

p a == a        # => true
p a == b        # => false
p a == "soup"   # => false
p a == c        # => false
p a == d        # => false
p d == e        # => true