thanks for your answer. The aspect was raised by students since in some aspects the compiler of CodeRunner behaves differently from the compiler in our IDE (Code::Blocks). Our CodeRunner configuration treats some warning as errors, while this is not the case in Code::Blocks. Our course contains practical exams that are solved entirely in CodeRunner/Moodle and therefore such a capability would ease the familiarization with the compiler of CodeRunner. However, I assume that this is only an issue for beginners in programming.
We envisioned this idea only for very simple programs (e.g., mathematical functions) without complex testcases/templates. Thereby, students could observe the behavior of their programs with different inputs. I agree that this solution would not scale very well to more complex cases.
However, I think we have found a solution for this issue without changing CodeRunner by decreasing the size of the code that students have to enter during the practical examinations (i.e. single statements instead of complete programs).
Thanks for the pointer to repl.it, we will definitely have a look into this.