Method testAssertWarnsContext

Lib/test/test_unittest/test_case.py:1662–1708

(self)

                self.assertWarns(DeprecationWarning, _runtime_warn)

    def testAssertWarnsContext(self):
        # Believe it or not, it is preferable to duplicate all tests above,
        # to make sure the __warningregistry__ $@ is circumvented correctly.
        def _runtime_warn():
            warnings.warn("foo", RuntimeWarning)
        _runtime_warn_lineno = inspect.getsourcelines(_runtime_warn)[1]
        with self.assertWarns(RuntimeWarning) as cm:
            _runtime_warn()
        # A tuple of warning classes is accepted
        with self.assertWarns((DeprecationWarning, RuntimeWarning)) as cm:
            _runtime_warn()
        # The context manager exposes various useful attributes
        self.assertIsInstance(cm.warning, RuntimeWarning)
        self.assertEqual(cm.warning.args[0], "foo")
        self.assertIn("test_case.py", cm.filename)
        self.assertEqual(cm.lineno, _runtime_warn_lineno + 1)
        # Same with several warnings
        with self.assertWarns(RuntimeWarning):
            _runtime_warn()
            _runtime_warn()
        with self.assertWarns(RuntimeWarning):
            warnings.warn("foo", category=RuntimeWarning)
        # Failure when no warning is triggered
        with self.assertRaises(self.failureException):
            with self.assertWarns(RuntimeWarning):
                pass
        # Custom message
        with self.assertRaisesRegex(self.failureException, 'foobar'):
            with self.assertWarns(RuntimeWarning, msg='foobar'):
                pass
        # Invalid keyword argument
        with self.assertRaisesRegex(TypeError, 'foobar'):
            with self.assertWarns(RuntimeWarning, foobar=42):
                pass
        # Failure when another warning is triggered
        with warnings.catch_warnings():
            # Force default filter (in case tests are run with -We)
            warnings.simplefilter("default", RuntimeWarning)
            with self.assertRaises(self.failureException):
                with self.assertWarns(DeprecationWarning):
                    _runtime_warn()
        # Filters for other warnings are not modified
        with warnings.catch_warnings():
            warnings.simplefilter("error", RuntimeWarning)
            with self.assertRaises(RuntimeWarning):
                with self.assertWarns(DeprecationWarning):
                    _runtime_warn()

    def testAssertWarnsNoExceptionType(self):
        with self.assertRaises(TypeError):