This article addresses refinement and testing based on CSP models, when we distinguish input and output events. In a testing experiment, the tester (or the environment) controls the inputs, and the system under test controls the outputs. The standard models and refinement relations of CSP, however, do not differentiate inputs and outputs and are not, therefore, entirely suitable for testing. Here, we consider an alphabet of events partitioned into inputs and outputs, and we present a novel refusal-testing model for CSP with a notion of input-output refusal-traces refinement. We compare that with the ioco relation often used in testing, and we find that it is more widely applicable and stronger. This means that mistakes found using traditional ioco testing do indicate mistakes in the development. Finally, we provide a CSP testing theory that takes into account inputs and outputs. With our theory, it becomes feasible to develop techniques and tools for automatic generation of realistic and sound tests from CSP models. Our work reconciles the normally disparate areas of refinement and (formal) testing by identifying how ioco testing can be used to inform refinement-based results and vice-versa.

中文翻译：

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CSP 中的输入和输出

当我们区分输入和输出事件时，本文将讨论基于 CSP 模型的细化和测试。在测试实验中，测试者（或环境）控制输入，而被测系统控制输出。然而，CSP 的标准模型和细化关系不区分输入和输出，因此不完全适合测试。在这里，我们考虑划分为输入和输出的事件字母表，并且我们提出了一种新颖的 CSP 拒绝测试模型，其中包含输入-输出拒绝跟踪细化的概念。我们将其与测试中经常使用的 ioco 关系进行比较，我们发现它的适用范围更广，更强大。这意味着使用传统 ioco 测试发现的错误确实表明了开发中的错误。最后，我们提供了考虑输入和输出的 CSP 测试理论。根据我们的理论，开发用于从 CSP 模型自动生成真实和合理的测试的技术和工具变得可行。我们的工作通过确定如何使用 ioco 测试来告知基于细化的结果，反之亦然，从而协调通常不同的细化和（正式）测试领域。