declare module_function

Gemfile

source 'https://rubygems.org'

gem 'json'

group :test do
   gem 'minitest'
   gem 'test-unit'
end

json_utilities.rb

module JsonUtilities
  module_function

  # compares two json objects (Array, Hash, or String to be parsed) for equality.
  # Returns true if the objects are equivalent, false otherwise
  def compare_json(json1, json2)

    # return false if classes mismatch or don't match our allowed types
    unless((json1.class == json2.class) && (json1.is_a?(String) || json1.is_a?(Hash) || json1.is_a?(Array)))
      return false
    end

    # Parse objects to JSON if Strings
    json1,json2 = [json1,json2].map! do |json|
      json.is_a?(String) ? JSON.parse(json) : json
    end
    return compare_json0(json1, json2)
  end

  def compare_json0(json1, json2)
    # initializing result var in the desired scope
    result = false

    # If an array, loop through each subarray/hash within the array and recursively call self with these objects for traversal
    if(json1.is_a?(Array))
      # Lengths must match
      return false unless (json1.length==json2.length)
      result = true # Zero length is also valid
      json1.each_with_index do |obj, index|
        json1_obj, json2_obj = obj, json2[index]
        result = compare_json0(json1_obj, json2_obj)
        # End loop once a false match has been found
        break unless result
      end
    elsif(json1.is_a?(Hash))

      # If a hash, check object1's keys and their values object2's keys and values

      # first check that there are the same number of keys
      return false unless (json1.keys.length==json2.keys.length)

      # created_at and updated_at can create false mismatches due to occasional millisecond differences in tests
      [json1,json2].each { |json| json.delete_if {|key,value| ["created_at", "updated_at"].include?(key)} }

      json1.each do |key,value|

        # both objects must have a matching key to pass
        return false unless json2.has_key?(key)

        json1_val, json2_val = value, json2[key]

        result = compare_json0(json1_val, json2_val)
        # End loop once a false match has been found
        break unless result
      end
    end

    return result ? true : (json1 == json2)
  end
end

tc_json_utilities.rb

require_relative 'json_utilities'
require "minitest/autorun"
require 'json'

class TestJsonUtilities < MiniTest::Unit::TestCase
  def test_same
        initial=JSON.parse(<<eos)
{
   "firstName": "John",
   "lastName": "Smith",
   "isAlive": true,
   "age": 25,
   "height_cm": 167.6,
   "address": {
      "streetAddress": ["Big Street|6,5"],
      "city": "New York",
      "state": "NY",
      "postalCode": "10021-3100"
   },
   "phoneNumbers": [
      {
         "type": "home",
         "number": "212 555-1234"
      },
      {
         "type": "office",
         "number": "646 555-4567"
      }
   ],
   "children": [],
   "spouse": null
}
eos
       test=JSON.parse(<<eos)
{"firstName": "John", "lastName": "Smith", "height_cm": 167.6, "age": 25, "address": {"streetAddress": ["Big Street|6,5"], "state": "NY", "postalCode": "10021-3100", "city": "New York"}, "isAlive": true, "spouse": null, "children": [], "phoneNumbers": [{"number": "212 555-1234", "type": "home"}, {"number": "646 555-4567", "type": "office"}]}
eos
       puts JSON.pretty_generate(test)
       assert(JsonUtilities.compare_json(initial,test),"Big comparison fails")
    end

    def test_empty_array_in_hash
       assert(JsonUtilities.compare_json('{"foo": []}','{"foo": []}'))
    end

    def test_string_in_array
       assert(JsonUtilities.compare_json('["foo"]','["foo"]'),"String in array fails")
    end

    def test_empty_array
       assert(JsonUtilities.compare_json('[]','[]'))
    end

    def test_json2_hash_with_extra_key
       a='{"foo":"bar"}'
       b='{"foo":"bar", "bar":"baz"}'
       assert(JsonUtilities.compare_json(a,b)==false,"fails with an extra key in jsonb")
       assert(JsonUtilities.compare_json(b,a)==false,"fails with an extra key in jsona")
    end

    def test_null_hash_value_equality
       a='{"foo": null}'
       assert(JsonUtilities.compare_json(a,a))
    end

end