faker_excluding_generator.rb

# Example of how to create a lazy generator for Faker that
# can exclude certain values.
#
# How to run:
# ruby faker_excluding_generator.rb
#

require "faker"
require "test/unit"

# build a lazy generator
def generator(excluding: Set[], &block)
  Enumerator.new do |yielder|
    loop do
      e = block.call
      next if excluding.include?(e)

      yielder << e
    end
  end
end

# or a lambda
def lambda_generator
  lambda do |excluding, &block|
    100.times do
      result = block.call
      next if excluding.include?(result)

      return result
    end
  end
end

class ExclusiveTest < Test::Unit::TestCase
  def test_generator
    address_generator = generator(excluding: Set["US"]) do
      Faker::Address.country_code
    end

    1000.times do
      address = address_generator.next

      assert address.is_a? String
      assert_not_equal address, "US"
    end
  end

  def test_lambda_generator
    1000.times do
      address = lambda_generator.call(Set["US"]) do
        Faker::Address.country_code
      end

      assert address.is_a? String
      assert_not_equal address, "US"
    end
  end
end