How do I check if code is being run from a nose-test?

Question

I have some code which is used in a unit test. However, the library it loads requires some data which isn't actually required for the nose-test, because that data is mocked out by the unit test. I'd like to protect the file-reads in the library so that they don't get called in the case of a nose test.

Is there an easy way to do this?

I can probably do something with sys.modules, or the initial command line, but I'd prefer something more elegant, if it exists.

Answer 1

As mentioned in comments, the structure of this code is a mess, and part of the point of the tests is to make sure that I don't break things when I refactor...

So, for now, (unless someone gives me a better answer), I'm using:

if 'nose' not in sys.modules.keys():
    <read the data>

Answer 2

Correct approach would be to mock all code with side-effects (I'll assume that what you do not want) with empty mocks.

Given tested_module my_module:

def do_something_and_destroy_world():
    destroy_world()
    return None

Sample test file is:

import mock
import unittest

import my_module

class MyTest(unittest.TestCase):
    def testSomethingUgly(self):
        with mock.patch('my_module.destroy_world', return_value=None):
            result = do_something_and_destroy_world()
            self.assertIsNone(result)

When tests are run, assertion will be correct, and destroy_world wouldn't be called - instead it'll get replaced with empty mock with fixed return value.