How do I import the Django DoesNotExist exception?
DjangoUnit TestingExceptionDjango Problem Overview
I'm trying to create a UnitTest to verify that an object has been deleted.
from django.utils import unittest
def test_z_Kallie_can_delete_discussion_response(self):
...snip...
self._driver.get("http://localhost:8000/questions/3/want-a-discussion")
self.assertRaises(Answer.DoesNotExist, Answer.objects.get(body__exact = '<p>User can reply to discussion.</p>'))
I keep getting the error:
DoesNotExist: Answer matching query does not exist.
Django Solutions
Solution 1 - Django
You can also import ObjectDoesNotExist from django.core.exceptions, if you want a generic, model-independent way to catch the exception:
from django.core.exceptions import ObjectDoesNotExist
try:
SomeModel.objects.get(pk=1)
except ObjectDoesNotExist:
print 'Does Not Exist!'
Solution 2 - Django
You don't need to import it - as you've already correctly written, DoesNotExist is a property of the model itself, in this case Answer.
Your problem is that you are calling the get method - which raises the exception - before it is passed to assertRaises. You need to separate the arguments from the callable, as described in the unittest documentation:
self.assertRaises(Answer.DoesNotExist, Answer.objects.get, body__exact='<p>User can reply to discussion.</p>')
or better:
with self.assertRaises(Answer.DoesNotExist):
Answer.objects.get(body__exact='<p>User can reply to discussion.</p>')
Solution 3 - Django
DoesNotExist is always a property of the model that does not exist. In this case it would be Answer.DoesNotExist.
Solution 4 - Django
One thing to watch out for is that the second parameter to assertRaises needs to be a callable - not just a property. For instance, I had difficulties with this statement:
self.assertRaises(AP.DoesNotExist, self.fma.ap)
but this worked fine:
self.assertRaises(AP.DoesNotExist, lambda: self.fma.ap)
Solution 5 - Django
self.assertFalse(Answer.objects.filter(body__exact='<p>User...discussion.</p>').exists())
Solution 6 - Django
This is how I do such a test.
from foo.models import Answer
def test_z_Kallie_can_delete_discussion_response(self):
...snip...
self._driver.get("http://localhost:8000/questions/3/want-a-discussion")
try:
answer = Answer.objects.get(body__exact = '<p>User can reply to discussion.</p>'))
self.fail("Should not have reached here! Expected no Answer object. Found %s" % answer
except Answer.DoesNotExist:
pass # all is as expected