I have a function that takes in user input via std::cin:

std::getline(std::cin, in);

and creates a corresponding data structure by matching it with a regular expression. The function then returns this data structure.

I'm using boost.test and I want to create a unit test to check that the output data type is correct given some inputs. However I don't know how to go about it since the input isn't passed as an argument to the function.

EDIT: Is there a simple way to create a boost test case that feeds the function a string via standard input?