feat: add task to create a pending enterprise learner for an assignment

[pwnage101]

ENT-7539

[iloveagent57]

Looking good, couple of random thoughts.

[iloveagent57]

I don't quite understand what this means - are you talking specifically about 429 HTTPErrors, or celery task retries? And could there be HTTP errors that aren't about rate limiting that cause this task to fail?

[pwnage101]

An LMS/enterprise API response with any 4xx/5xx status code will cause the celery task to retry. If execution enters on_failure, then we can infer that it was the result of exceeding max_retries if the exc is any of the following:

enterprise-access/enterprise_access/tasks.py

Lines 20 to 26 in c9681b7

	autoretry_for = (
	RequestsConnectionError,
	RequestsTimeoutError,
	HTTPError,
	OperationalError,
	BrazeClientError,
	)

If anything, I should probably write this like:

Suggested change

	if isinstance(exc, HTTPError):
	# The failure resulted from too many retries. This fact would be a useful thing to record in a "reason"
	# field on the assignment if one existed.
	logger.error('The task failure resulted from too many retries.')
	if isinstance(exc, (RequestsConnectionError, RequestsTimeoutError, HTTPError, OperationalError)):
	# The failure resulted from too many retries. This fact would be a useful thing to record in a "reason"
	# field on the assignment if one existed.
	logger.error('The task failure resulted from too many retries.')

So, as much as I'd like to refactor LoggedTaskWithRetry to be more specific about which specific status codes to treat as retryable, I think that's probably out of scope since it would either mean impacting all other consumers of LoggedTaskWithRetry, or adding configurability to LoggedTaskWithRetry that could fit into a different ticket/feature request.

[pwnage101]

I searched the world wide web again and discovered that there's actually a sanctioned way to unit test celery workers using a celery-provided fixture that spins up a mini celery worker in a separate process (see conftest.py). This made it way easier to test the celery task retry logic.

[iloveagent57]

This is great, great find on that pytest celery thing. One small request to shore up a unit test.