How to force an exception in django in order to test it in django

Question

I've really searched for how to patch Whatever.objects.get_or_create, but I can't get any suggestion or idea how to do it.

Well, my problem is that I have something like this:

def create_and_get_object(
    name, request, save_url=True, data=None):

    try:
        (object_type_, created) = Object.objects.get_or_create(
            name=name)
        try:
        ...
    except Exception:
        obj = None
        msg = ("Failed to get or create object `Object` with"
                "name='%s'" % name)
        logger_.exception(msg, extra={'request': request})
    return obj

So, I want to test that Object.objects.get_or_create throws an exception somewhen...

I was trying with Mock(side_effect=Exception()) but I don't really know how to use it to get what I expect.

All this to get 100% coverage for that function (exception lines are not covered), and many others with exceptions like that.

What is the correct way to test this, and code like this?

What am I doing wrong?

Answer 1

I like to use python's with statement with mock's patch.object. In your case it should be smth like this:

from mock import patch
from django.test import TestCase
from django.db.models.manager import Manager
from anothermodule import create_and_get_object


class TestCreateAndGetObject(TestCase):
    def test_exception_throwing(self):
        with patch.object(Manager, 'get_or_create') as mock_method:
            mock_method.side_effect = Exception("test error")

            result = create_and_get_object('test', 'test')
            self.assertIsNone(result)

Should work in theory, hope that helps.