ffaker Ruby Library

The ffaker library overrides const_missing for its modules. If you attempt to access a constant that is not explicitly defined in a module, ffaker will attempt to find a matching data file in the ffaker/data directory.

For example, accessing FFaker::Name::FIRST_NAMES for the first time will trigger the library to look for and load data from ffaker/data/name/first_names and set that constant automatically.

When building new ffaker modules, you must use the deterministic methods provided by ModuleUtils to ensure the output respects the random seed.

Instead of using standard Ruby Array methods, use these equivalents:

• fetch_sample(array) instead of Array#sample.
• fetch_sample(array, count: n) instead of Array#sample(n).
• shuffle(array) instead of Array#shuffle.

Note that standard calls to rand will automatically use the correct internal RNG without modification. If you need to pass the RNG to other Ruby methods, you can access it via FFaker::Random.

To use ffaker in a standard Ruby project, install the gem using the following command:

gem install ffaker

Then, require it in your Ruby code:

require 'ffaker'

To make ffaker deterministic with RSpec (including seeds passed via --seed nnn), add the following configuration to your spec_helper.rb or equivalent file:

• Use config.before(:all) to set the seed based on the RSpec seed.
• Use config.before(:each) to reset the RNG so each test is independent.

# spec_helper.rb
RSpec.configure do |config|
  config.before(:all)  { FFaker::Random.seed=config.seed }
  config.before(:each) { FFaker::Random.reset! }
end

To ensure your ffaker modules are deterministic, use the DeterministicHelper in your tests.

1. Include the helper: include DeterministicHelper in your test class.
2. Test multiple methods: Use assert_methods_are_deterministic(Class, :method1, :method2) for methods that do not require arguments.
3. Test specific blocks: Use assert_deterministic { ... } for methods that require arguments or have complex behavior.

# Example usage in a test class
class MyModuleTest < Minitest::Test
  include DeterministicHelper

  def test_methods_without_args
    assert_methods_are_deterministic(
      FFaker::NewFFakerModule,
      :method_name, :other_method_name, :another_method_name
    )
  end

  def test_some_method
    assert_deterministic { FFaker::NewFFakerModule.some_method(:required_argument) }
  end
end

If you are using Ruby on Rails, add ffaker to your Gemfile within the development and test groups to ensure it is available during local development and automated testing:

group :development, :test do
  gem 'ffaker'
end

After updating your Gemfile, run the following command in your terminal:

bundle install

Once required, you can access various data generators through the FFaker module. Common modules include Name and Internet.

require 'ffaker'

FFaker::Name.name       #=> "Christophe Bartell"
FFaker::Internet.email  #=> "kirsten.greenholt@corkeryfisher.info"

Use the FFaker::GenderRU module to generate gender-related strings in Russian.

• maybe: Returns a random selection from common gender identities (e.g., 'мужчина', 'женщина', 'агендер').
• random: Returns a random selection.
• sample: Returns a random selection from a sample set.
• binary: Attempts to return a binary gender value. Note that this method may raise FFaker::UniqueUtils::RetryLimitExceeded if it cannot find a unique value within the retry limit.