# File lib/test/unit/assertions.rb, line 63
      def assert(boolean, message=nil)
        _wrap_assertion do
          assertion_message = nil
          case message
          when nil, String, Proc
          when AssertionMessage
            assertion_message = message
          else
            error_message = "assertion message must be String, Proc or "
            error_message << "#{AssertionMessage}: "
            error_message << "<#{message.inspect}>(<#{message.class}>)"
            raise ArgumentError, error_message, filter_backtrace(caller)
          end
          assert_block("assert should not be called with a block.") do
            !block_given?
          end
          assertion_message ||= build_message(message,
                                              "<?> is not true.",
                                              boolean)
          assert_block(assertion_message) do
            boolean
          end
        end
      end