将 cout 和 stdout 都重定向到 C++ 中的字符串以进行单元测试

问题描述

我正致力于在单元测试中获取一些遗留代码，有时感知现有程序行为的唯一方法是通过控制台输出.

我在网上看到了很多关于如何将标准输出重定向到 C++ 中的另一个文件的示例，但是有没有一种方法可以将其重定向到内存中的流，这样我的测试就不必依赖磁盘了?

我想将遗留代码发送到 stdout 的任何内容放入 std::string 中，以便我可以轻松地在输出中找到.

编辑

遗留代码太糟糕了，它使用了 cout <<.. 和 printf.这是我目前所拥有的:

void TestSuite::setUp(void){oldStdoutBuf = std::cout.rdbuf();std::cout.rdbuf(consoleOutput.rdbuf());}void TestSuite::tearDown(void){std::cout.rdbuf(oldStdoutBuf);}

问题是这不会不使用 printf 捕获输出.我想要两者兼而有之的东西.有什么想法吗?

std::stringstream 可能就是你要找的.

更新
好吧，这是一个小技巧，但也许你可以这样做来获取 printf 输出:

char huge_string_buf[MASSIVE_SIZE];freopen("NUL", "a", 标准输出);setbuf(标准输出，巨大的字符串缓冲区)；

请注意，Linux 应使用/dev/null"而不是NUL".这将迅速开始填满 big_string_buffer.如果您希望能够在缓冲区已满后继续重定向输出，则必须调用 fflush()，否则会引发错误.有关详细信息，请参阅 std::setbuf.

I'm working on getting some legacy code under unit tests and sometimes the only way to sense an existing program behavior is from the console output.

I see lots of examples online for how to redirect stdout to another file in C++, but is there a way I can redirect it to an in-memory stream so my tests don't have to rely on the disk?

I'd like to get anything that the legacy code sends to stdout into a std::string so I can easily .find on the output.

Edit

The legacy code is so bad that it users a mixture of cout << .. and printf. Here is what I have so far:

void TestSuite::setUp(void)
{
    oldStdoutBuf = std::cout.rdbuf();
    std::cout.rdbuf(consoleOutput.rdbuf());
}
void TestSuite::tearDown(void)
{
    std::cout.rdbuf(oldStdoutBuf);
}

The problem is that this does not capture output using printf. I would like something that gets both. Any ideas?

std::stringstream may be what you're looking for.

UPDATE
Alright, this is a bit of hack, but maybe you could do this to grab the printf output:

char huge_string_buf[MASSIVE_SIZE];
freopen("NUL", "a", stdout);
setbuf(stdout, huge_string_buffer);

Note you should use "/dev/null" for linux instead of "NUL". That will rapidly start to fill up huge_string_buffer. If you want to be able to continue redirecting output after the buffer is full you'll have to call fflush(), otherwise it will throw an error. See std::setbuf for more info.

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