I have a model called Thing with an attribute called name, and I want name to be a char field that's only 3 characters long.
How do I write a test for that?
class TestCase1(TestCase):
def test1(self):
thing = Thing(name='1234')
that test should fail. How do I properly write the test so that the test passes when that object fails?
If you're expecting Thing(name='1234') to raise an exception, there are two ways to deal with this.
One is to use Django's assertRaises (actually from unittest/unittest2):
def mytest(self):
self.assertRaises(FooException, Thing, name='1234')
This fails unless Thing(name='1234') raises a FooException error. Another way is to catch the expected exception and raise one if it doesn't happen, like this:
def mytest(self):
try:
thing = Thing(name='1234')
self.fail("your message here")
except FooException:
pass
Obviously, replace the FooException with the one you expect to get from creating the object with too long a string. ValidationError?
A third option (as of Python 2.7) is to use assertRaises as a context manager, which makes for cleaner, more readable code:
def mytest(self):
with self.assertRaises(FooException):
thing = Thing(name='1234')
Sadly, this doesn't allow for custom test failure messages, so document your tests well. See https://hg.python.org/cpython/file/2.7/Lib/unittest/case.py#l97 for more details.
def failUnlessRaises(self, excClass, callableObj, *args, **kwargs) and then callableObj(*args, **kwargs). So in this post's example, it would be self.assertRaises(FooException, Thing, name='1234'). I'm not sure why my function signature is different, but that's what works.
assertRaises can also be used in a with statement like this: with self.assertRaises(FooException): thing = Thing(name='1234')I am currently using the expectedFailure decorator from unittest. That works as advertised: Fails when there is no error, passes when there is a failure.
I use expectedFailure to verify that my custom assert-routines actually work and not just rubberstamp everything OK.
import unittest
from django.test import TestCase
class EmojiTestCase(TestCase):
@unittest.expectedFailure
def testCustomAssert(self):
self.assertHappyFace(':(') # must fail.
But prints a warning-message during testing. I use it with Django and Nose. Which others have seen, too.
/usr/lib64/python3.4/unittest/case.py:525: RuntimeWarning: TestResult has no addExpectedFailure method, reporting as passes RuntimeWarning)
I came here to find a better solution, but found none. So I at least wanted to tell others that come what I've been working with.
In my previous project i had to do something like test driven development, so i have written some test case which must catch certain types of error. If it don't gets the error then i have messed up something. Here i share my code.
from django.test import TestCase
from django.contrib.auth.models import User
class ModelTest(TestCase):
def test_create_user_with_email(self):
with self.assertRaises(TypeError):
email = "[email protected]"
password = 'testpass1'
user = User.objects.create_user(
email = email,
password = password,)
self.assertEqual(user.email, email)
self.assertTrue(user.check_password(password))
You can see i have tried to create a user with email and password but default Django user model need "username" and "password" arguments to create user. So here my testcase must raise "TypeError". And that what i tried to do here.
In case anyone coming from search is looking for a method similar to @Chris, but doesn't like the x unittest displays when the test "fails successfully", I stumbled across this:
from django.test import TestCase
class ExampleTests(TestCase):
def test_fails(self): # Passes
with self.assertRaises(self.failureException):
self.assertTrue(False)
I needed it for a sanity check to make sure a custom assertion actually failed when it's supposed to fail.
Something like this should work:
thing = Thing.objects.create(name='1234')
# not sure if you need here .get() or if. create() truncates the field on its own
self.assertEqual(thing.name, '123') # or: self.assertEqual(len(thing.name), 3)
-- but such test looks weird :-)
Also, note that MySQLdb backend will raise Warning exception to notify you of truncating the string, so you might want to check it with assertRaises.
