I'm writing a RubyGem that can raise an ArgumentError if the arguments supplied to its single method are invalid. How can I write a test for this using RSpec?

The example below shows the sort of implementation I have in mind. The bar method expects a single boolean argument (:baz), the type of which is checked to make sure that it actually is a boolean:

module Foo
  def self.bar(options = {})
    baz = options.fetch(:baz, true)
    validate_arguments(baz)
  end

  def self.validate_arguments(baz)
    raise(ArgumentError, ":baz must be a boolean") unless valid_baz?(baz)
  end

  def self.valid_baz?(baz)
    baz.is_a?(TrueClass) || baz.is_a?(FalseClass)
  end
end