Adds FFaker::Bank.routing_number and account_number

Changelog.md

@@ -1,6 +1,8 @@
 ## development
 
   - Add your change HERE
+  - Add FFaker::Bank.accounting_number [@professor]
+  - Add FFaker::Bank.routing_number [@professor]
   - Adds FFaker::Crypto.sha256 [@professor]
   - Update README [@professor]
   - Adds FFaker::Number.between [@professor]

REFERENCE.md

@@ -38,6 +38,7 @@
  * [FFaker::Avatar](#ffakeravatar)
  * [FFaker::BaconIpsum](#ffakerbaconipsum)
  * [FFaker::Bank](#ffakerbank)
+ * [FFaker::BankUS](#ffakerbankus)
  * [FFaker::Book](#ffakerbook)
  * [FFaker::Boolean](#ffakerboolean)
  * [FFaker::CheesyLingo](#ffakercheesylingo)
@@ -932,6 +933,13 @@
 | `card_type` | mastercard, maestro, solo |
 | `iban` | DO50GCBH29467231689551372717, LU338569240126150859, BE89929107166643 |
 
+## FFaker::BankUS
+
+| Method | Example |
+| ------ | ------- |
+| `account_number(min_digits:, max_digits:)` | "2140767894", "30434706933238021" |
+| `rounting_number` | "270510171" |
+
 ## FFaker::Book
 
 | Method | Example |

lib/ffaker.rb

@@ -66,6 +66,7 @@ def self.bothify(masks)
   autoload :AWS, 'ffaker/aws'
   autoload :BaconIpsum, 'ffaker/bacon_ipsum'
   autoload :Bank, 'ffaker/bank'
+  autoload :BankUS, 'ffaker/bank_us'
   autoload :Book, 'ffaker/book'
   autoload :Boolean, 'ffaker/boolean'
   autoload :CheesyLingo, 'ffaker/cheesy_lingo'

lib/ffaker/bank_us.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+module FFaker
+  module BankUS
+    extend ModuleUtils
+    extend self
+
+    def account_number(min_digits: 9 , max_digits: 17)
+      FFaker.numerify('#' * rand(min_digits..max_digits))
+    end
+
+    def routing_number
+      partial_routing_number = FFaker.numerify('########')
+      ninth_digit = generate_checksum_digit(partial_routing_number)
+
+      "#{partial_routing_number}#{ninth_digit}"
+    end
+
+    private
+
+    def generate_checksum_digit(num_string)
+      num_array = num_string.chars.map(&:to_i)
+      (
+        7 * (num_array[0] + num_array[3] + num_array[6]) +
+          3 * (num_array[1] + num_array[4] + num_array[7]) +
+          9 * (num_array[2] + num_array[5])
+      ) % 10
+    end
+  end
+end

test/test_bank.rb

@@ -7,7 +7,7 @@ class TestBank < Test::Unit::TestCase
 
   assert_methods_are_deterministic(
     FFaker::Bank,
-    :iban, :card_number, :card_expiry_date, :card_type
+    :iban, :card_number, :card_expiry_date, :card_type, :account_number, :routing_number
   )
 
   def setup

test/test_bank_us.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+require_relative 'helper'
+
+class TestBankUS < Test::Unit::TestCase
+  include DeterministicHelper
+
+  assert_methods_are_deterministic(
+    FFaker::Bank,
+    :account_number, :routing_number
+  )
+
+  def setup
+    @tester = FFaker::BankUS
+  end
+
+  def test_account_number
+    assert_instance_of String, @tester.account_number
+    assert_match(/\A\d{8}\z/, @tester.account_number(min_digits: 8, max_digits: 8))
+    assert_match(/\A\d{12}\z/, @tester.account_number(min_digits: 12, max_digits: 12))
+  end
+
+  def test_routing_number
+    routing_number = @tester.routing_number
+    assert_match(/\A\d{9}\z/, routing_number)
+
+    checksum = (
+      7 * (routing_number[0].to_i + routing_number[3].to_i + routing_number[6].to_i) +
+        3 * (routing_number[1].to_i + routing_number[4].to_i + routing_number[7].to_i) +
+        9 * (routing_number[2].to_i + routing_number[5].to_i + routing_number[8].to_i)
+    ) % 10
+
+    assert_equal(0, checksum)
+  end
+end