Add module for generating driving licences (#1433)

doc/unreleased/driving_licence.md

@@ -0,0 +1,21 @@
+# Faker::DrivingLicence
+
+```ruby
+# Generate a licence number in GB format, as issued in England, Scotland and Wales
+# The DVSA does not publish their checksum algorithm, so the last 3 characters
+# are random
+# Optional arguments: last_name, initials, date_of_birth, gender
+Faker::DrivingLicence.british_driving_licence        #=> "MCDER712081VF7EK"
+Faker::DrivingLicence.british_driving_licence(last_name: "O'Carroll",
+                                              initials: "J",
+                                              gender: :female,
+                                              date_of_birth: Date.parse("1986-10-24")) #=> "OCARR815246J91HT"
+
+# Generate a Northern Irish licence number
+Faker::DrivingLicence.northern_irish_driving_licence #=> "70702548"
+
+# Generate a UK driving licence number in either GB or NI format, at a rate
+# consistent with their relative populations
+# Optional arguments: last_name, initials, date_of_birth, gender
+Faker::DrivingLicence.uk_driving_licence             #=> "OCARR815246J91HT"
+Faker::DrivingLicence.uk_driving_licence             #=> "70702548"

lib/faker/driving_licence.rb

@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+module Faker
+  class DrivingLicence < Base
+    GB_PADDING = '9999'
+    NI_CHANCE = 0.03 # NI Pop is about 3% of total UK population
+
+    class << self
+      def british_driving_licence(last_name: Faker::Name.last_name,
+                                  initials: Faker::Name.initials,
+                                  gender: random_gender,
+                                  date_of_birth: Faker::Date.birthday(18, 65))
+        [
+          gb_licence_padding(last_name, 5),
+          gb_licence_year(date_of_birth, gender),
+          gb_licence_padding(initials, 2),
+          gb_licence_checksum
+        ].join
+      end
+
+      def northern_irish_driving_licence
+        Faker::Number.number(8)
+      end
+
+      def uk_driving_licence(*args)
+        if Faker::Config.random.rand < NI_CHANCE
+          northern_irish_driving_licence
+        else
+          british_driving_licence(*args)
+        end
+      end
+
+      private
+
+      def random_gender
+        %i[male female].sample(random: Faker::Config.random)
+      end
+
+      def gb_licence_padding(str, num_chars)
+        prepped = str.upcase.gsub(%r{[^A-Z]}, '') + GB_PADDING
+        prepped[0..(num_chars - 1)]
+      end
+
+      def gb_licence_year(dob, gender)
+        decade = (dob.year / 10) % 10
+        year = dob.year % 10
+        month = gender == :female ? dob.month + 5 : dob.month
+        # Rubocop's preferred formatting is pretty gory
+        # rubocop:disable FormatString
+        "#{decade}#{'%02d' % month}#{'%02d' % dob.day}#{year}"
+        # rubocop:enable FormatString
+      end
+
+      def gb_licence_checksum
+        regexify(/[0-9][A-Z][A-Z]/)
+      end
+    end
+  end
+end

test/test_faker_driving_licence.rb

@@ -0,0 +1,68 @@
+# frozen_string_literal: true
+
+require_relative 'test_helper'
+
+class TestFakerDrivingLicence < Test::Unit::TestCase
+  def setup
+    @tester = Faker::DrivingLicence
+  end
+
+  def test_valid_gb_licence
+    sample = @tester.british_driving_licence
+    # GB Licence number is 16 characters long
+    assert_equal 16, sample.length
+    # First 5 characters are the last_name, right-padded with '9'
+    assert_match %r{[A-Z][A-Z9]{4}}, sample[0..4]
+    # Next 6 are digits
+    assert_match %r{[0-9]{6}}, sample[5..10]
+    # comprising:
+    # Single digit decade of birth
+    assert_includes 0..9, sample[5].to_i
+    # 2 digit month of birth (add 5 if female)
+    assert_includes 1..17, sample[6..7].to_i
+    # 2 digit day of birth
+    assert_includes 1..31, sample[8..9].to_i
+    # and least significant digit of birth year
+    assert_includes 0..9, sample[10].to_i
+    # Next 2 are first 2 initials of forenames, padded with '9'
+    assert_match %r{[A-Z][A-Z9]}, sample[11..12]
+    # Last stanza is a tie-breaker digit + 2 letter checksum
+    assert_match %r{[0-9][A-Z0-9]{2}}, sample[13..15]
+  end
+
+  def test_valid_northern_irish_licence
+    sample = @tester.northern_irish_driving_licence
+    # NI licence is an opaque 8-digit number
+    assert_equal 8, sample.length
+    assert_match %r{[0-9]{8}}, sample
+  end
+
+  def test_uk_licence
+    sample = @tester.uk_driving_licence
+    assert_includes [8, 16], sample.length
+  end
+
+  def test_british_licence_correctly_mangles_last_name
+    padded = @tester.british_driving_licence(last_name: 'Judd')
+    assert_equal 'JUDD9', padded[0..4]
+    truncated = @tester.british_driving_licence(last_name: 'Hamilton')
+    assert_match %r{HAMIL[0-9]}, truncated[0..5]
+    cleaned = @tester.british_driving_licence(last_name: "O'Carroll")
+    assert_equal 'OCARR', cleaned[0..4]
+  end
+
+  def test_british_licence_correctly_mangles_date_of_birth
+    date_of_birth = Date.parse('1978-02-13')
+    male = @tester.british_driving_licence(date_of_birth: date_of_birth, gender: :male)
+    assert_equal '702138', male[5..10]
+    female = @tester.british_driving_licence(date_of_birth: date_of_birth, gender: :female)
+    assert_equal '707138', female[5..10]
+  end
+
+  def test_british_licence_correctly_builds_initials
+    padded = @tester.british_driving_licence(initials: 'A')
+    assert_equal 'A9', padded[11..12]
+    truncated = @tester.british_driving_licence(initials: 'NLTC')
+    assert_equal 'NL', truncated[11..12]
+  end
+end

unreleased_CONTENT.md

@@ -52,6 +52,7 @@ Contents
   - [Faker::Demographic](doc/unreleased/demographic.md)
   - [Faker::Dessert](doc/unreleased/dessert.md)
   - [Faker::Device](doc/unreleased/device.md)
+  - [Faker::DrivingLicence](doc/unreleased/driving_licence.md)
   - [Faker::DrWho](doc/unreleased/dr_who.md)
   - [Faker::DumbAndDumber](doc/unreleased/dumb_and_dumber.md)
   - [Faker::Dune](doc/unreleased/dune.md)