Method assertIsInstance

Lib/unittest/case.py:1334–1342

Same as self.assertTrue(isinstance(obj, cls)), with a nicer default message.

(self, obj, cls, msg=None)

            self.fail(self._formatMessage(msg, standardMsg))

    def assertIsInstance(self, obj, cls, msg=None):
        """Same as self.assertTrue(isinstance(obj, cls)), with a nicer
        default message."""
        if not isinstance(obj, cls):
            if isinstance(cls, tuple):
                standardMsg = f'{safe_repr(obj)} is not an instance of any of {cls!r}'
            else:
                standardMsg = f'{safe_repr(obj)} is not an instance of {cls!r}'
            self.fail(self._formatMessage(msg, standardMsg))

    def assertNotIsInstance(self, obj, cls, msg=None):
        """Included for symmetry with assertIsInstance."""