This project demonstrates a bug that occurs when a chain is added to a chord. There are 6 tests:

Name	Test	async	Result
test_chord	group() | s()	yes	pass
test_chord_chain_one_task	group() | s() | s()	yes	fail
test_chord_chain_two_tasks	group() | s() | s() | s()	yes	pass
test_chord_sync	group() | s()	no	pass
test_chord_chain_one_task_sync	group() | s() | s()	no	pass
test_chord_chain_two_tasks_sync	group() | s() | s() | s()	no	pass

Strangely, only the asynchronous version of a chord followed by another task shows a problem; the synchronous version passes. Adding another task to the chain (3rd row) "fixes" the problem.

Install

pip install -r requirements.txt

for celery 3.1.13

Run Tests

nosetests

The test class spins up redis-server and a celery worker.

This is the test that fails:

def test_chord_chain_one_task(self):
    c = (group([add.si(2, 2), add.si(4, 4)])
         | add_list.s()
         | mul.s(2))
    res = c.apply_async()
    self.assertEqual(res.get(), 24)

Try Celery Master

The current master branch (2fddb876e1b966c3540aadbbc2257dfd493abb85) fails every async test with:

TypeError: group object got multiple values for keyword argument 'task_id'

To install celery master branch: pip install -r requirements_master.txt