Python unittest /测试装置测试是否已加载模块

Question

I'm using another SO recommendation for importing simplejson , which reads as follows:

try:
    import simplejson as json
except ImportError:
    import json

However, in writing my unittest to see if "one of the json modules" has in fact been imported, I'm stuck in the circular nightmare that is my own design! /sigh.

class AreAllModulesLoaded(unit.TestCase):
    """Test to make sure all modules are loaded"""
    def test_json(self):
        try:
            self.assertTrue("simplejson" in sys.modules)
        except:
            try:
                self.assertTrue("json" in sys.modules)
            except AssertionError:
                raise

I thought something like this would have worked, however, on inspection of the unittest.failUnless or unittest.assertTrue (I have tried both), it raises the failure and the test stops (it's failing because I am causing the failure by only loading json instead of simplejson )...

My intended goal is I want my unittest to confirm that EITHER json or simplejson was loaded. How might I go about this?

I have thought about capturing "truthiness" prior to assertion, and then only pass "True" or "False", but that doesn't feel right for unittesting only because I thought that this should have been part the unittest proper rather than a work-around (that's my opinion, maybe you feel differently). For example, I had thought about doing something like (python-esque pseduoish code):

_simplejsonLoaded = "simplejson" in sys.modules
_jsonLoaded = "json" in sys.modules

self.assertTrue(_simplejsonLoaded or _jsonLoaded)

(I am new to formal unittesting - so, if something seems crazy here please let me know).

Other information:

• Im using Python 2.6 (for work reasons - can't change that)
• Windows and Linux

I'm

Answer 1

I don't think you need the try/except stuff in the TestCase

import sys
import unittest
try:
    import simplejson as json
except ImportError:
    import json

class TestSomething(unittest.TestCase):
    def test_json(self):
        if ('json' in sys.modules or 'simplejson' in sys.modules):
            self.assert_(True, "some kind of json loaded")
        else:
            self.fail()

if __name__ == "__main__":
    unittest.main()

Answer 2

Well, the question is whether you really care which particular library you have imported. When you import simplejson as json then you json symbol in sys.modules as well, and that's what really matters, right? Of course, you can then check whether the imported json library has all methods and properties required for your own program, but that's another issue. So, isn't the correct definition of the test just:

import sys
import my_own_module

class TestSomething(unittest.TestCase):
    def test_json(self):
        self.assertIn('json', sys.modules,
                      "json API not loaded")