Fix Luhn algorithm used in french companie's SIRET and sweden SSN

REFERENCE.md

@@ -1028,8 +1028,8 @@
 | Method | Example |
 | ------ | ------- |
 | `name` | Pascal, Vasseur and Mendes, Rossi et fils, Guillou-Collet |
-| `siren` | 739836110, 690890420, 300789380 |
-| `siret` | 06746846000000, 70493562000500, 45666261000350 |
+| `siren` | 739836112, 690890421, 300789385 |
+| `siret` | 06746846200006, 70493562600504 , 45666261800358 |
 | `suffix` | SA, Groupe, SARL |
 
 ## FFaker::CompanyIT

lib/ffaker/utils/module_utils.rb

@@ -38,21 +38,12 @@ def unique(max_retries = 10_000)
 
     # http://en.wikipedia.org/wiki/Luhn_algorithm
     def luhn_check(number)
-      multiplications = []
-
-      number.chars.each_with_index do |digit, i|
-        multiplications << i.even? ? digit.to_i * 2 : digit.to_i
-      end
-
-      sum = 0
-      multiplications.each do |num|
-        num.to_s.each_byte do |character|
-          sum += character.chr.to_i
-        end
-      end
-
-      control_digit = (sum % 10).zero? ? 0 : (((sum / 10) + 1) * 10) - sum
-      control_digit.to_s
+      sum = number.chars
+                  .map(&:to_i)
+                  .reverse
+                  .each_with_index
+                  .sum { |digit, index| index.even? ? (2 * digit).digits.sum : digit }
+      ((10 - sum%10)%10).to_s
     end
   end
 end

test/test_module_utils.rb

@@ -44,4 +44,13 @@ def generator.test
     FFaker::UniqueUtils.clear
     generator.unique.test
   end
+
+  def test_luhn_check
+    obj = Object.new
+    obj.extend FFaker::ModuleUtils
+    assert obj.luhn_check("97248708") == "6"
+    assert obj.luhn_check("1789372997") == "4"
+    assert obj.luhn_check("8899982700037") == "1"
+    assert obj.luhn_check("1234567820001") == "0"
+  end
 end