Method test_traceback

Lib/test/_test_multiprocessing.py:3170–3206

(self)

    @warnings_helper.ignore_fork_in_thread_deprecation_warnings()
    def test_traceback(self):
        # We want ensure that the traceback from the child process is
        # contained in the traceback raised in the main process.
        if self.TYPE == 'processes':
            with self.Pool(1) as p:
                try:
                    p.apply(self._test_traceback)
                except Exception as e:
                    exc = e
                else:
                    self.fail('expected RuntimeError')
            p.join()
            self.assertIs(type(exc), RuntimeError)
            self.assertEqual(exc.args, (123,))
            cause = exc.__cause__
            self.assertIs(type(cause), multiprocessing.pool.RemoteTraceback)
            self.assertIn('raise RuntimeError(123) # some comment', cause.tb)

            with test.support.captured_stderr() as f1:
                try:
                    raise exc
                except RuntimeError:
                    sys.excepthook(*sys.exc_info())
            self.assertIn('raise RuntimeError(123) # some comment',
                          f1.getvalue())
            # _helper_reraises_exception should not make the error
            # a remote exception
            with self.Pool(1) as p:
                try:
                    p.map(sqr, exception_throwing_generator(1, -1), 1)
                except Exception as e:
                    exc = e
                else:
                    self.fail('expected SayWhenError')
                self.assertIs(type(exc), SayWhenError)
                self.assertIs(exc.__cause__, None)
            p.join()

    @classmethod
    @warnings_helper.ignore_fork_in_thread_deprecation_warnings()