[Tutor] Unit testing command-line options from argparse or optparse

[Knacktus]

Am 18.05.2010 22:49, schrieb Serdar Tumgoren:
> Hello all,
>
> Does anyone have advice for writing unit tests against variables set 
> by command-line options?
>
> I have a program I'd like to run in either "debug" or "live" mode, 
> with various settings associated with each. Below is some pseudo-code 
> that shows what I'd like to do:
>
> <<snipped argparse import and options setup >>
> mode = p.parse_args() #always set to either --debug or --live
>
> if mode.live:
>     recipients = ['jsmith at email.com <mailto:jsmith at email.com>', 
> 'janedoe at email.com <mailto:janedoe at email.com>']
>     # set logging to a file
> elif mode.debug:
>     recipients = ['admin at admin.com <mailto:admin at admin.com>']
>     # log to stdout
>
> The "live" and "debug" attributes are set by command-line flags passed 
> to the argparse module. What I'd like to do is write tests that check 
> whether various settings (recipients, logging, etc.) are configured 
> properly based on the command-line options.
>
> But if "mode" is not set until runtime, I clearly can't import it into 
> my suite of unit tests, right? Is there some standard testing approach 
> to this problem (perhaps mocking?) that you all can recommend?
>
> I'd greatly appreciate it.
> Serdar
>
>
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I just had a look at the optparse documentation ... huuu, quite heavier 
than I have expected.... But to your question:

You could reorganise your main module. Put all your code which is on 
module level into a function called "main" with mode as argurment and 
add the neat "if __name__ == "__main__" condition at the end of your 
module to parse the command line options and call your main function. 
When you import your module to your test, you have to call the "main" 
function "manually" and can pass a mock for the mode as required. Let's 
say your main module is called "serdars_main_module"

serdars_main_module.py:
--------------------------
########################################################
def main(mode):
     # all the program logic
      if mode.live:
         recipients = ['jsmith at email.com <mailto:jsmith at email.com>', 
'janedoe at email.com <mailto:janedoe at email.com>']
         # set logging to a file
      elif mode.debug:
         recipients = ['admin at admin.com <mailto:admin at admin.com>']
         # log to stdout
     # ...

if __name__ == "__main__":
     mode = p.parse_args() #always set to either --debug or --liv
     main(mode)
#########################################################

Then your test module could look like:

serdars_test_module.py:
-------------------------
#########################################################
import serdars_main_module
import unittest

class ArgParseMock(object):
     def __init__(self, live, debug):
         self.live = live
         self.debug = debug

class TestDebugMode(unittest.TestCase):
     def test_live_mode(self):
         mode = ArgParseMock(True, False) # create the mock for the 
arguments
         serdars_main_module.main(mode) # call the main logic with the mock
         # ....
     def test_debug_mode(self):
         mode = ArgParseMock(False, True) # create the mock for the 
arguments
         serdars_main_module.main(mode) # call the main logic with the mock
         # ....
##########################################################

Hope that helps,

Jan
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