将cout和stdout都重定向到C ++中的字符串以进行单元测试 [英] Redirect both cout and stdout to a string in C++ for Unit Testing

问题描述

我正在努力在单元测试下获得一些遗留代码，有时，感知现有程序行为的唯一方法是从控制台输出。

我看到很多在线示例如何将stdout重定向到C ++中的另一个文件，但是有一种方法，我可以将它重定向到内存流，所以我的测试不必依赖磁盘？

我想获得任何遗留代码发送到stdout到std ::字符串，所以我可以很容易地在输出.find。

编辑

旧代码太糟糕了，因此用户混合使用 cout< .. 和 printf 。这是我到目前为止：

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

问题是这样做不使用printf。我想要的东西，得到两者。任何想法？

解决方案

std :: stringstream 可能是您要查找的内容。

UPDATE

好​​吧，这是一个黑客，但也许你可以这样做，以获取printf输出：

  char huge_string_buf [MASSIVE_SIZE]; 
 freopen（NUL，a，stdout）; 
 setbuf（stdout，huge_string_buffer）;注意，你应该使用/ dev / null替换linux，而不是NUL。这将迅速开始填满huge_string_buffer。如果你想要能够在缓冲区满后继续重定向输出，你必须调用fflush（），否则会抛出一个错误。请参见  std :: setbuf  了解更多信息。
 
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?
解决方案
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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