Django/Python assertRaises with message check

You can just use assertRaisesRegexp.

with self.assertRaisesRegexp(ValidationError, "Both"):    de.full_clean()

When you use it as a context manager the 2nd argument is a regular expression to search through the exception's string representation.

Since the question is related to Django, you could also use the assertRaisesMessage context manager when inheriting from django's TestCase.

from django.test import TestCaseclass ExceptionTest(TestCase):    def test_call_raises_exception_with_custom_message(self):        with self.assertRaisesMessage(Exception, 'My custom message!'):            call_that_causes_exception()    

Note: The assertRaisesMessage manager does an in lookup on the exceptions message: Say your exception raises "My custom message!", asserting for "custom message" passes. Bear this in mind especially if you have multiple (custom) exceptions with similar messages.

(E.g. two different exceptions raising "My custom message! Further details..." and "My custom message! No details." would both pass an assert for "My custom message!").

Nowadays you can use assertRaises as a context manager. This way you can capture the exception and inspect it later.

with self.assertRaises(SomeException) as cm:    do_something()the_exception = cm.exceptionself.assertEqual(the_exception.error_code, 3)