Question

I have an executable that I need to run some tests on in C++ – and the testing is going to take place on all of Windows, Linux and Mac OSes.

I was hoping for input on:

• How would I interface with the previously built executable from my code? Is there some kind of command functionality that I can use? Also, since I think the commands change between OSes, I’d need some guidance in figuring out how I could structure for all three OSes.

EDIT – Interface = I need to be able to run the executable with a command line argument from my C++ code.

• The executable when called from the commandline also ouputs some text onto a console – how would I be able to grab that ouput stream (I’d need to record those outputted values as part of my tests).

Feel free to ask me follow up questios.

Cheers!

Answer 1

As I understand, you want to:

1. Spawn a new process with arguments not known at runtime.
2. Retrieve the information printed to stdout by the new process.

Libraries such as QProcess can spawn processes, however, I would recommend doing it by hand for both Windows and MacOS/Linux as using QProcess for this case is probably overkill.

For MacOS/Linux, here’s what I would do:

1. Set up a pipe in the parent process. Set the read end of the pipe to a new file descriptor in the parent.
2. fork.
3. In newly created child process, set stdout (file descriptor #1) to the write end of the pipe.
4. execvp in the newly created child process and pass the target executable along with what arguments you want to give it.
5. From the parent process, wait for the child (optional).
6. From the parent process, read from the file descriptor you indicated in Step 1.