Add Faker::Vehicle.singapore_license_plate (#1410)

* Add Singapore vehicle license plate * Update en-SG.yml
faker-ruby · Oct 18, 2018 · 8b7e160 · 8b7e160
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diff --git a/doc/vehicle.md b/doc/vehicle.md
@@ -56,7 +56,10 @@ Faker::Vehicle.mileage(50_000) #=> 81557
 Faker::Vehicle.mileage(50_000, 250_000) #=> 117503
 Faker::Vehicle.kilometrage #=> 35378
 
-# Random vehicle license plate
+# Random vehicle license plate (USA by default)
 Faker::Vehicle.license_plate #=> "DEP-2483"
 Faker::Vehicle.license_plate('FL') #=> "977 UNU"
+
+# Random vehicle license plate for Singapore (if locale is set)
+Faker::Vehicle.singapore_license_plate #=> "SLV1854M"
 ```
diff --git a/lib/faker/vehicle.rb b/lib/faker/vehicle.rb
@@ -10,6 +10,8 @@ class Vehicle < Base
     VIN_MAP = '0123456789X'
     VIN_WEIGHTS = '8765432X098765432'
     VIN_REGEX = /^[A-Z0-9]{3}[A-Z0-9]{5}[A-Z0-9]{1}[A-Z0-9]{1}[A-Z0-0]{1}[A-Z0-9]{1}\d{5}$/
+    SG_CHECKSUM_WEIGHTS = [3, 14, 2, 12, 2, 11, 1].freeze
+    SG_CHECKSUM_CHARS = 'AYUSPLJGDBZXTRMKHEC'
 
     class << self
       def vin
@@ -96,6 +98,12 @@ def license_plate(state_abreviation = '')
         regexify(bothify(fetch(key)))
       end
 
+      def singapore_license_plate
+        key = 'vehicle.license_plate'
+        plate_number = regexify(bothify(fetch(key)))
+        "#{plate_number}#{singapore_checksum(plate_number)}"
+      end
+
       private
 
       def first_eight(number)
@@ -125,6 +133,17 @@ def vin_char_to_number(char)
 
         VIN_MAP[index]
       end
+
+      def singapore_checksum(plate_number)
+        padded_alphabets = format('%3s', plate_number[/^[A-Z]+/]).tr(' ', '-').split('')
+        padded_digits = format('%04d', plate_number[/\d+/]).split('').map(&:to_i)
+        sum = [*padded_alphabets, *padded_digits].each_with_index.reduce(0) do |memo, (char, i)|
+          value = char.is_a?(Integer) ? char : char.ord - 64
+          memo + (SG_CHECKSUM_WEIGHTS[i] * value)
+        end
+
+        SG_CHECKSUM_CHARS.split('')[sum % 19]
+      end
     end
   end
 end
diff --git a/lib/locales/en-SG.yml b/lib/locales/en-SG.yml
@@ -31,3 +31,5 @@ en-SG:
       default_country: [Singapore]
     phone_number:
       formats: ['+65 6### ####', '+65 9### ####', '+65 8### ####']
+    vehicle:
+      license_plate: 'S??####'
diff --git a/test/test_en_sg_locale.rb b/test/test_en_sg_locale.rb
@@ -31,4 +31,8 @@ def test_en_sg_name_methods
     assert Faker::Name.first_name.is_a? String
     assert Faker::Name.name.is_a? String
   end
+
+  def test_singapore_license_plate
+    assert_match(/^S[A-Z]{2}\d{1,4}[A-Z]{1}$/, Faker::Vehicle.singapore_license_plate)
+  end
 end