C ++单元测试检查输出是否正确 [英] c++ unit testing check output is correct

问题描述

如果我想编写自己的test.cpp来检查另一个.cpp文件是否以我希望的输出方式输出，是否有必要在不显式打印的情况下进行操作?

If I want to write my own test.cpp that checks if another .cpp file is outputting the way I want it to output, is there anyway to do it without explicitly printing it?

换句话说，有诸如

assert(output_of_file_being_tested, "this is the correct output");

其中output_of_file_being_tested是应该被"cout"的东西.

where output_of_file_being_tested is something that's supposed to be "cout"ed.

推荐答案

解决方案不是对输出流进行硬编码.以某种方式将对std::ostream的引用传递给您的代码，然后使用std::stringstream在测试环境中收集输出.

The solution is not to hard-code the output stream. Pass a reference to std::ostream to your code somehow, and use std::stringstream to collect the output in test environment.

例如，这是您的另一个.cpp"文件的内容:

For example, this is the content of your "another .cpp" file:

void toBeTested(std::ostream& output) {
        output << "this is the correct output";
}

因此，在生产/发布代码中，您可以将std::cout传递给函数:

So in your production/release code you may pass std::cout to the function:

void productionCode() {
        toBeTested(std::cout);
}

在测试环境中，您可以将输出收集到字符串流中并检查其正确性:

while in the test environment you may collect the output to a sting stream and check it for correctness:

// test.cpp
#include <sstream>
#include <cassert>

void test() {
        std::stringstream ss;
        toBeTested(ss);
        assert(ss.str() == "this is the correct output");
}

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