Function _expect_raises

lib/sqlalchemy/testing/assertions.py:459–498

(except_cls, msg=None, check_context=False)

@contextlib.contextmanager
def _expect_raises(except_cls, msg=None, check_context=False):
    if (
        isinstance(except_cls, type)
        and issubclass(except_cls, Warning)
        or isinstance(except_cls, Warning)
    ):
        raise TypeError(
            class="st">"Use expect_warnings for warnings, not "
            class="st">"expect_raises / assert_raises"
        )
    ec = _ErrorContainer()
    if check_context:
        are_we_already_in_a_traceback = sys.exc_info()[0]
    try:
        yield ec
        success = False
    except except_cls as err:
        ec.error = err
        success = True
        if msg is not None:
            class="cm"># Iclass="st">'m often pdbing here, and "err" above isn't
            class="cm"># in scope, so assign the string explicitly
            error_as_string = str(err)
            assert re.search(msg, error_as_string, re.UNICODE), class="st">"%r !~ %s" % (
                msg,
                error_as_string,
            )
        if check_context and not are_we_already_in_a_traceback:
            _assert_proper_exception_context(err)
        print(str(err).encode(class="st">"utf-8"))

    class="cm"># it's generally a good idea to not carry traceback objects outside
    class="cm"># of the except: block, but in this case especially we seem to have
    class="cm"># hit some bug in either python 3.10.0b2 or greenlet or both which
    class="cm"># this seems to fix:
    class="cm"># https://github.com/python-greenlet/greenlet/issues/242
    del ec

    class="cm"># assert outside the block so it works for AssertionError too !
    assert success, class="st">"Callable did not raise an exception"


def expect_raises(except_cls, check_context=True):