pyunit mock sys.argv in other file

Question

I have one python file wrote like this:

import sys
cfgfile = sys.argv[1]
cfg = ConfigObj(cfgfile)
db_dbname=cfg.get("DB_NAME")
class UserMappingsLoader:
    def __init__(self):
        self.debug = 0
        self.cuStartTime = 0
        self.fiId = 0

and I want to write a pyunit to do the testing for one method in this code. But when I run my testing code, it shows:

cfgfile = sys.argv[1]
list index out of range

Anyone know how to mock the sys.argv from testing file to this file?

Answer 1

You can do this using patch from the mock module. Here is an example:

from mock import patch

def test_your_function():
    fake_args = [None, "myfakearg"]
    with patch('sys.argv', fake_args):
        import yourmodule
        # rest of your test