Efficient testing of time-dependent, asynchronous code

Abstract

Time is important. New software rarely works as a standalone service— usually, it is part of a much bigger network of interconnected applications, running on different hardware, operating systems and designed with various technology stacks. Even applications which do not need network connectivity, such as some embedded devices, rely on time-based events for task scheduling. However, support for testing time-dependent code is often not sufficient both on operating system level and on framework/library level, and generally, requires special ways of designing software to provide sufficient testability. Custom design often means implementing special testing library or modifying the source code for test purposes. This paper points out some of the things that may go wrong when using these approaches, introduces a portable model of time-based computation and presents zurvan—an open-source library for Node.js applications which provides an abstraction over time and allows users to efficiently test time-dependent, asynchronous code. Advantages of using presented model include test case repeatability, increased code testability and shorter test suite execution times.