Mocking Celery `self.request` attribute for bound tasks when called directly

Question

I have a task foobar:

@app.task(bind=True)
def foobar(self, owner, a, b):
   if already_working(owner): # check if a foobar task is already running for owner.
       register_myself(self.request.id, owner) # add myself in the DB.
   return a + b

How can I mock the self.request.id attribute? I am already patching everything and calling directly the task rather than using .delay/.apply_async, but the value of self.request.id seems to be None (as I am doing real interactions with DB, it is making the test fail, etc…).

For the reference, I'm using Django as a framework, but I think that this problem is just the same, no matter the environment you're using.

Answer 1

Disclaimer: Well, I do not think it was documented somewhere and this answer might be implementation-dependent.

Celery wraps his tasks into celery.Task instances, I do not know if it swaps the celery.Task.run method by the user task function or whatever.

But, when you call a task directly, you call __call__ and it'll push a context which will contain the task ID, etc…

So the idea is to bypass __call__ and Celery usual workings, first:

• we push a controlled task ID: foobar.push_request(id=1) for example.
• then, we call the run method: foobar.run(*args, **kwargs).

Example:

@app.task(bind=True)
def foobar(self, name):
    print(name)
    return foobar.utils.polling(self.request.id)

@patch('foobar.utils.polling')
def test_foobar(mock_polling):
    foobar.push_request(id=1)
    mock_polling.return_value = "done"
    assert foobar.run("test") == "done"
    mock_polling.assert_called_once_with(1)

Answer 2

You can call the task synchronously using

task = foobar.s(<args>).apply()

This will assign a unique task ID, so the value will not be None and your code will run. Then you can check the results as part of your test.