```ruby
module TestHelpers
  #
  # Authentication test helper
  #
  module AuthHelper
    #
    # Gets an authentication token for User.first
    #
    def auth_token
      auth_token_for(User.first)
    end

    #
    # Gets an auth token for the provided user
    #
    def auth_token_for_user(user)
      user.extend_authentication_token(true)
      user.auth_token
    end

    #
    # Adds an authentication token to the hash data or string URL
    # This prevents us from having to keep adding the :auth_token
    # key to any GET/POST/PUT etc. data that is needed
    #
    def add_auth_token(data, user = User.first)
      if data.is_a? Hash
        data[:auth_token] = auth_token
      elsif data.is_a? String
        # If we have a question mark, we need to add a query paramater using &
        # otherwise use ?
        data << (data.include?('?') ? "&" : "?") << "auth_token=#{auth_token}"
      end
      data
    end

    #
    # Alias for above for nicer usage (e.g., get with_auth_token "http://")
    #
    def with_auth_token(data)
      add_auth_token data
    end

    module_function :auth_token
    module_function :add_auth_token
    module_function :auth_token_for_user
  end
end
```

Add missing module function for with_auth_token
user
```ruby
module TestHelpers
  #
  # Authentication test helper
  #
  module AuthHelper
    #
    # Gets an authentication token for User.first
    #
    def auth_token
      auth_token_for(User.first)
    end

    #
    # Gets an auth token for the provided user
    #
    def auth_token_for_user(user)
      user.extend_authentication_token(true)
      user.auth_token
    end

    #
    # Adds an authentication token to the hash data or string URL
    # This prevents us from having to keep adding the :auth_token
    # key to any GET/POST/PUT etc. data that is needed
    #
    def add_auth_token(data, user = User.first)
      if data.is_a? Hash
        data[:auth_token] = auth_token
      elsif data.is_a? String
        # If we have a question mark, we need to add a query paramater using &
        # otherwise use ?
        data << (data.include?('?') ? "&" : "?") << "auth_token=#{auth_token}"
      end
      data
    end

    #
    # Alias for above for nicer usage (e.g., get with_auth_token "http://")
    #
    def with_auth_token(data, user = User.first)
      add_auth_token data, user
    end

    module_function :auth_token
    module_function :add_auth_token
    module_function :auth_token_for_user
    module_function :with_auth_token
  end
end
```
assistant