id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
33161	Do not ignore transaction durability errors within TestCase	Krzysztof Jagiełło	Krzysztof Jagiełło	"Currently there is a discrepancy in how durable atomic blocks are handled in `TransactionTestCase` vs `TestCase`. Using the former, nested durable atomic blocks will, as expected, result in a `RuntimeError`. Using the latter however, the error will go unnoticed as the durability check is turned off. 

I have faced some issues with this behaviour in a codebase where we heavily utilize `TestCase` and where we recently started to introduce durable atomic blocks – the durability errors do not surface until the code hits staging/production. The solution could be to switch over to `TransactionTestCase` for the test classes that hit code paths with durable atomic blocks, but having to identify which tests could be affected by this issue is a bit inconvenient. And then there is the performance penalty of using `TransactionTestCase`. 

So, to the issue at hand. The durability check is disabled for `TestCase` because otherwise durable atomic blocks would fail immediately as `TestCase` wraps its tests in transactions. We could however add a marker to the transactions created by `TestCase`, keep a stack of active transactions and make the durability check take the stack of transactions with their respective markers into account. This way we could easily detect when a durable atomic block is directly within a transaction created by `TestCase` and skip the durability check only for this specific scenario. 

To better illustrate what I am proposing here, I have prepared a PoC patch. Let me know what you think!

Patch: https://github.com/django/django/pull/14919"	New feature	closed	Testing framework	dev	Normal	fixed		David Seddon Adam Johnson Ian Foote Hannes Ljungberg	Ready for checkin	1	0	0	0	0	0