Question

I have an nunit Test in C#, that calls a C# wrapper of a function in a C++ DLL.
The C++ code uses std::cerr to output various messages.

These messages cannot be redirected using nunit-console /out /err or /xml switch.
In nunit (the GUI version) the output does not appear anywhere.

I would like to be able to see this output in nunit (GUI version).
Ideally I would like to be able to access this output in the Test.

Thanks for any help.

Answer 1

Redirecting std::cerr is a matter of replacing the stream buffer with your own.
It is important to restore in original buffer before we exit. I don’t know what your wrapper looks like, but you can probably figure out how to make it read output.str().

#include <iostream>
#include <sstream>
#include <cassert>

using namespace std;

int main()
{
    streambuf* buf(cerr.rdbuf());
    stringstream output;

    cerr.rdbuf(output.rdbuf());
    cerr << "Hello, world!" << endl;

    assert(output.str() == "Hello, world!\n");
    cerr.rdbuf(buf);

    return 0;
}