Just as an example, it might seem illogical. I have a get_name function as below, and wanted to write a automated script to call this function and enter to the raw_inp
You can also substitute stdin with StringIO (aka memory file) instead of real file. This way the entered text will be in your testing code instead of separate text file.
based on Anand S Kumar's (+1):
def run():
import sys
import StringIO
f1 = sys.stdin
f = StringIO.StringIO('entered text') # <-- HERE
sys.stdin = f
get_name()
f.close()
sys.stdin = f1
Also, for more sophisticated testing of interactive commandline functions/tools you may want to check the pyexpect package.