[issue14819] Add `assertIsSubclass` and `assertNotIsSubclass` to `unittest.TestCase`

[Patrick Smith]

New submission from Patrick Smith <pjs482 at gmail.com>:

The attached patch adds two helper methods to `unittest.TestCase`: `assertIsSubclass` and `assertIsNotSubclass`. These methods are similar to the `assertIsInstance` and `assertIsNotInstance` methods that are already part of `unittest.TestCase`. They allow one to test if a class is a subclass of another class using the `issubclass` builtin.

These methods can be used like:
    self.assertIsSubclass(cls, parent_cls)

These new methods provide a nicer error message and more consistent interface over the alternatives:
    self.assertTrue(issubclass(cls, parent_cls))
    assert issubclass(cls, parent_cls)

----------
components: Library (Lib)
files: assertissubclass.patch
keywords: patch
messages: 160762
nosy: patricksmith
priority: normal
severity: normal
status: open
title: Add `assertIsSubclass` and `assertNotIsSubclass` to `unittest.TestCase`
type: enhancement
Added file: http://bugs.python.org/file25600/assertissubclass.patch

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<http://bugs.python.org/issue14819>
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