Paddock Equality

paddock.rb

# In this example case when we create paddock objects we want them to be equal
# to each other if their name and area are the same and their lat/lng are "close
# enough" to each other. In our case we want "close enough" to mean the lat and
# lng match up to four decimal places.
#
# Download this file and the corresponding test case file tc_paddock.rb. Run the
# test case file like this `ruby tc_paddock.rb`. Currently all tests fail.

# Please make the changes you feel are necessary to make the tests pass, then
# make a gist with your version of paddock.rb and let us know.

require 'bigdecimal' 

class Paddock

  attr_accessor :lat, :lng, :name, :area, :modify_lat, :modify_lng
  ATTR_NOT_COMPARED = [:lat, :lng]

  def initialize(lat:, lng:, name:, area:)
    self.lat  = lat
    self.lng  = lng
    self.name = name
    self.area = area
    self.modify_lat = precission lat
    self.modify_lng = precission lng
  end

  # 
  # Make number precission with 4 decimal places
  # 
  def precission(number, decimal_point = 4)
    BigDecimal::new(number, 0).truncate(decimal_point).to_f 
  end

  # 
  # Get Attributes
  # eg: converting from :@lat to :lat
  # 
  def attributes
    instance_variables.map { |i| i.to_s.delete("@").to_sym }
  end

  # 
  # Get Attributes for compare value
  # will remove unecessary attributes :lat, :lng
  # 
  def attributes_compare
    attributes.reject! { |attr| ATTR_NOT_COMPARED.include? attr }
  end

  # 
  # override compare with double equals
  # eg: @paddock == @paddock2
  # 
  def ==(paddock_compare)
    attributes_compare.each { |attr| return false if self.send(attr) != paddock_compare.send(attr) }
    return true
  end

  # 
  # override compare with eql?
  # eg: @paddock.eql? @paddock2
  # 
  def eql?(paddock_compare)
    self == paddock_compare
  end

  # 
  # Override hash for check object uniq in array
  # Ref: https://www.ruby-forum.com/topic/165653
  # 
  def hash
    [modify_lng, modify_lng, name, area].hash
  end
end

tc_paddock.rb

require 'test/unit'
require_relative 'paddock'

class TestPaddock < Test::Unit::TestCase
  def setup
    @p1 = Paddock.new(lat: -31.9415, lng: 115.8418, name: 'Agworld HQ', area: 10)
    @p2 = Paddock.new(lat: -31.94154, lng: 115.84183, name: 'Agworld HQ', area: 10)
    @p3 = Paddock.new(lat: -31.9405, lng: 115.8408, name: 'Agworld HQ', area: 11)
    @p4 = Paddock.new(lat: -31.9415, lng: 115.8418, name: 'Agworld Branch', area: 10)
  end

  def test_double_equals
    assert(@p1 == @p2, 'p1 should == p2')
    assert_equal(@p1 == @p3, false, 'p1 should not == p3')
    assert_equal(@p1 == @p4, false, 'p1 should not == p4')
  end

  def test_eql?
    assert(@p1.eql?(@p2), 'p1 should eql? p2')
    assert_equal(@p1.eql?(@p3), false, 'p1 should not eql? p3')
  end

  def test_uniq
    assert_equal([@p1, @p2].uniq.length, 1)
    assert_equal([@p1, @p3].uniq.length, 2)
  end
end