RuntimeError: Unfulfilled dependency at run time

[e-mon]

Luigi (also gokart) implicitly assumes that the file is output when the Task run is executed, and if it is not, an error Unfulfilled dependency at run time is raised like following sample code.

This behavior is a bit confusing, so how about making sure that the file is output when the run completes?

import gokart
import luigi

class TaskA(gokart.TaskOnKart):
    def run(self):
        pass

class TaskB(gokart.TaskOnKart):
    def requires(self):
        return TaskA()

    def run(self):
        pass

if __name__ == '__main__':
    gokart.run(['TaskB', '--local-scheduler'], set_retcode=True)

error:

Traceback (most recent call last):
  File "/Users/e-mon/.pyenv/versions/3.7.5/lib/python3.7/site-packages/luigi/worker.py", line 176, in run
    raise RuntimeError('Unfulfilled %s at run time: %s' % (deps, ', '.join(missing)))
RuntimeError: Unfulfilled dependency at run time: TaskA__99914b932b

[vaaaaanquish]

I think the best way to do this is to have the ability to support in luigi.
spotify/luigi#3095