Google Authenticator OTP calculator (Used in my Cucumber tests)

google_authenticator.rb

module DeviseGoogleAuthenticatorHelpers
  #
  # Returns a valid One Time Password for the Google Authenticator gem.
  #
  # @param user [User] instance for which a valid OPT is requested.
  # @return [Integer] first valid calculated OTP
  #
  def a_valid_otp_for(user)
    calculate_otps_from(user.gauth_secret).first
  end

  private

  def calculate_otps_from(secret)
    valid_vals = []

    valid_vals << ROTP::TOTP.new(secret).at(Time.now)
    (1..User.ga_timedrift).each do |cc|
      valid_vals << ROTP::TOTP.new(secret).at(Time.now.ago(30 * cc))
      valid_vals << ROTP::TOTP.new(secret).at(Time.now.in(30 * cc))
    end

    valid_vals
  end
end

World(DeviseGoogleAuthenticatorHelpers)