# File lib/test/unit/assertions.rb, line 191
      def assert_instance_of(klass, object, message="")
        _wrap_assertion do
          klasses = nil
          klasses = klass if klass.is_a?(Array)
          assert_block("The first parameter to assert_instance_of should be " +
                       "a Class or an Array of Class.") do
            if klasses
              klasses.all? {|k| k.is_a?(Class)}
            else
              klass.is_a?(Class)
            end
          end
          klass_message = AssertionMessage.maybe_container(klass) do |value|
            "<#{value}>"
          end
          full_message = build_message(message, "<?> expected to be an instance of\n? but was\n<?>.\n", object, klass_message, object.class)
          assert_block(full_message) do
            if klasses
              klasses.any? {|k| object.instance_of?(k)}
            else
              object.instance_of?(klass)
            end
          end
        end
      end