# File lib/test/unit/assertions.rb, line 324
      def assert_instance_of(klass, object, message="")
        _wrap_assertion do
          if klass.is_a?(Array)
            klasses = klass
          else
            klasses = [klass]
          end
          assert_block("The first parameter to assert_instance_of should be " +
                       "a Class or an Array of Class.") do
            klasses.all? {|k| k.is_a?(Class)}
          end
          klass_message = AssertionMessage.maybe_container(klass) do |value|
            "<#{value}>"
          end
          full_message = build_message(message, "<?> was expected to be instance_of\\\\?\n? but was\n<?>.\n", object, klass_message, object.class)
          assert_block(full_message) do
            klasses.any? {|k| object.instance_of?(k)}
          end
        end
      end