def METHOD_NAME(self):
    self.workflow = BpmnWorkflow(self.spec, self.subprocesses)
    set_data = self.workflow.spec.task_specs['set_data']
    set_data.script = """in_1, unused = 1, True"""
    with self.assertRaises(WorkflowDataException) as exc:
        self.workflow.do_engine_steps()
    self.assertEqual(exc.exception.data_input.bpmn_id, 'in_2')