Use more specific assertions in tests

[Jon Dufresne]

Like #23620. I found more patterns that could use more specific assertions.

Example patterns:

self.assertEqual(expression, False)
self.assertEqual(expression, True)
self.assertEqual(expression, None)
self.assertNotEqual(expression, None)

Will change these to:

self.assertFalse(expression)
self.assertTrue(expression)
self.assertIsNone(expression)
self.assertIsNotNone(expression)

Python docs on assertions: ​https://docs.python.org/3/library/unittest.html#assert-methods

[Jon Dufresne]

​https://github.com/django/django/pull/6760

[Tim Graham]

As noted on the PR, I'm not convinced about the merits of assertTrue/False rather than assertEqual(val, True) since such the former pass if bool(val) is True/False which might be too loose.

[Jon Dufresne]

Incorporated suggestion. Thanks.

[Tim Graham <timograham@…>]

In 4f336f6:

Fixed #26747 -- Used more specific assertions in the Django test suite.

[Tim Graham <timograham@…>]

In 13d60298:

[1.10.x] Fixed #26747 -- Used more specific assertions in the Django test suite.

Backport of 4f336f66523001b009ab038b10848508fd208b3b from master

[Tim Graham <timograham@…>]

In 7b08e01c:

Refs #26747 -- Corrected a method name in tutorial05.

[Tim Graham <timograham@…>]

In e5103de:

[1.10.x] Refs #26747 -- Corrected a method name in tutorial05.

Backport of 7b08e01c1358aedbd46fa26c91d4613d642ff609 from master