测试写入Java OutputStream的内容 [英] Testing what's written to a Java OutputStream

问题描述

我即将为直接输出到OutputStream的XML解析Java类编写junit测试。例如 xmlWriter.writeString（foo）; 会产生类似< aTag> foo< / aTag> 的内容写入XmlWriter实例中保存的输出流。问题是如何测试这种行为。一个解决方案当然是让OutputStream成为FileOutputStream然后通过打开写入的文件来读取结果，但它不是很优雅。

I am about to write junit tests for a XML parsing Java class that outputs directly to an OutputStream. For example xmlWriter.writeString("foo"); would produce something like <aTag>foo</aTag> to be written to the outputstream held inside the XmlWriter instance. The question is how to test this behaviour. One solution would of course be to let the OutputStream be a FileOutputStream and then read the results by opening the written file, but it isn't very elegant.

推荐答案

使用 ByteArrayOutputStream 然后使用 toByteArray（）。这不会测试如何它写入流（一次一个字节或作为一个大缓冲区），但通常你不应该关心它。

Use a ByteArrayOutputStream and then get the data out of that using toByteArray(). This won't test how it writes to the stream (one byte at a time or as a big buffer) but usually you shouldn't care about that anyway.

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