Prohibit usage of TestCase.assertRaises() (DBR001)

Ensures that TestCase.assertRaises() is never used since asserting an exception without the actual error message leads to false positives. Use TestCase.assertRaisesMessage() instead.

Wrong:

from django.test import TestCase


class MyTestCase(TestCase):

    def test_my_function(self):
        with self.assertRaises(RuntimeError):
            my_function()

Correct:

from django.test import TestCase


class MyTestCase(TestCase):

    def test_my_function(self):
        with self.assertRaisesMessage(RuntimeError, "Ooops, that's an error."):
            my_function()