[BUG] It is not possible to unit test a Python timer function

[davidmytton]

Azure provides documentation for unit testing HTTP and Queue Python functions. This is done by creating a mock QueueMessage or HTTPRequest. However, there is no documentation for creating a unit test for Timer functions.

There is a TimerRequest class, but creating a new instance of it fails with the following error:

req = func.TimerRequest()

TypeError: Can't instantiate abstract class TimerRequest with abstract methods past_due

Having posted on StackOverflow to ask about the correct approach for this e.g. if I want to test behaviour of a function which has past_due set, but had no answers, I'm opening this bug to request that Python functions allow unit testing.

[anthonychu]

Try passing True or False to the constructor to set past_due. Example here: https://github.com/Azure/azure-functions-python-library/blob/8ef845cd8f688c9aba5ed7b96f0951cba4856e12/azure/functions/timer.py#L35

[davidmytton]

Thanks, this worked. Can I suggest that this is added to the docs as an example alongside the others?

[joaosantos15]

That wasn't working for me anymore, in the end I created a class with the past_due attribute set to True, and that did the trick (also on stack overflow):

    import unittest
    from azure.functions import TimerRequest
    from my_func import main

    class MockTimer():
        def __init__(self):
            self.past_due = True


    class TestFunction(unittest.TestCase):
        def test_my_function(self):
            timer = MockTimer()
            resp = main(timer)

[hallvictoria]

Hi everyone, sorry for the delay on this. We're currently working on a fix that will allow for unit testing of TimerRequest without the additional workarounds. You'll be able to create a TimerRequest object like this: func.TimerRequest(). This change will be included in azure-functions>=1.25.0.

I've updated our wiki to show specifically the TimerRequest example. With azure-functions >= 1.21.0, you'll also be able to test the functions by invoking them directly (ie, by calling python function_app.py). The wiki covers the setup, and we're in the process of updating the developer reference as well to include this information.