Function _assert_proper_exception_context

lib/sqlalchemy/testing/assertions.py:372–390

assert that any exception we're catching does not have a __context__ without a __cause__, and that __suppress_context__ is never set. Python 3 will report nested as exceptions as "during the handling of error X, error Y occurred". That's not what we want to do. we want these except

(exception)

def _assert_proper_exception_context(exception):
    """assert that any exception we're catching does not have a __context__
    without a __cause__, and that __suppress_context__ is never set.

    Python 3 will report nested as exceptions as "during the handling of
    error X, error Y occurred". That's not what we want to do.  we want
    these exceptions in a cause chain.

    """

    if (
        exception.__context__ is not exception.__cause__
        and not exception.__suppress_context__
    ):
        assert False, (
            "Exception %r was correctly raised but did not set a cause, "
            "within context %r as its cause."
            % (exception, exception.__context__)
        )


def assert_raises(except_cls, callable_, *args, **kw):