Python code in simulate mode

Question

I have a python code that reads output from command line:

import subprocess

def get_prg_output():
    p = subprocess.Popen(['ls', '-l'], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    out, err = p.communicate()
    return out

print get_prg_output()

In my office I want to simulate result in this mode:

def get_prg_output():
    return 'ok - program executed'

print get_prg_output()

Is there an elegant way to do this without comment out the original function?

I've try this:

import subprocess

debug = True

if not debug:
    def get_prg_output():
        p = subprocess.Popen(['ls', '-l'], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        out, err = p.communicate()
        return out
else:
    def get_prg_output():
        return 'ok - program executed'
print get_prg_output()

but I don't like it.

Thanks

Answer 1

I'd do something like this:

def _get_prg_output_real():
    p = subprocess.Popen(['ls', '-l'], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    out, err = p.communicate()
    return out

def _get_prg_output_fake():
    return 'ok - program executed'

Here you can toggle between:

get_prg_output = _get_prg_output_fake

or

get_prg_output = _get_prg_output_real

based on user input, or commandline arguments or config files or commenting/uncommenting a single line of code ...

Answer 2

def get_prg_output_fake():
    return 'ok - program executed'

then, if you want to enable this simulation, just do

get_prg_output=get_prg_output_fake

Answer 3

I'd use an environment variable (or a command switch) to control it myself so you don't have to make code changes to test.

import os
import subprocess

def _get_prg_output_real():
    p = subprocess.Popen(['ls', '-l'], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    out, err = p.communicate()
    return out

def _get_prg_output_fake():
    return 'ok - program executed'

if os.environ.get('DEBUG').lower() == 'true':
    get_prg_output = _get_prg_output_fake
else:
    get_prg_output = get_prg_output_real