class RSpec::Mocks::MethodReference

def self.method_visibility_for(object, method_name)
  instance_method_visibility_for(class << object; self; end, method_name).tap do |vis|
    # If the method is not defined on the class, `instance_method_visibility_for`
    # returns `nil`. However, it may be handled dynamically by `method_missing`,
    # so here we check `respond_to` (passing false to not check private methods).
    #
    # This only considers the public case, but I don't think it's possible to
    # write `method_missing` in such a way that it handles a dynamic message
    # with private or protected visibility. Ruby doesn't provide you with
    # the caller info.
    return :public if vis.nil? && object.respond_to?(method_name, false)
  end
end