Simple Multi-DB read replica unit test raises TransactionManagementError

[TTimo]

(I posted this on the ML initially, but I suspect it's a bug in the testing framework. A complete example is attached. Empty unit test, with no routers and a read replica DB setup gives a TransactionManagementError)

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I started assessing multi-db support in Django 1.5.1, I'm interested in having read replicas and a write master.

I've figured out all the easy stuff: using TEST_MIRROR in the DATABASES setting, writing a simple router that splits read and write traffic, all according to the documentation. I can run a test server and issue some calls manually, but I have not been able to run simple unit tests.

The most simple test I can build fails during _pre_setup() with a "TransactionManagementError: Transaction managed block ended with pending COMMIT/ROLLBACK"

My databases are MySQL EC2 RDS instances, the replication is working fine, the tables are InnoDB etc.

I know there is active development around transaction management code in Django lately, so maybe I've stumbled on a bug? I'm attaching a simple test setup that should make it easy to reproduce.

Any advice would be greatly appreciated.

Cheers,
TTimo

./manage.py test readreplica
Creating test database for alias 'default'...
E
======================================================================
ERROR: testTest (readreplica.tests.Test)

---

Traceback (most recent call last):

File "/usr/local/lib/python2.7/dist-packages/django/test/testcases.py", line 240, in call

self._pre_setup()

File "/usr/local/lib/python2.7/dist-packages/django/test/testcases.py", line 462, in _pre_setup

self._fixture_setup()

File "/usr/local/lib/python2.7/dist-packages/django/test/testcases.py", line 822, in _fixture_setup

if not connections_support_transactions():

File "/usr/local/lib/python2.7/dist-packages/django/test/testcases.py", line 809, in connections_support_transactions

for conn in connections.all())

File "/usr/local/lib/python2.7/dist-packages/django/test/testcases.py", line 809, in <genexpr>

for conn in connections.all())

File "/usr/local/lib/python2.7/dist-packages/django/utils/functional.py", line 48, in get

res = instance.dict[self.func.name] = self.func(instance)

File "/usr/local/lib/python2.7/dist-packages/django/db/backends/init.py", line 627, in supports_transactions

self.connection.leave_transaction_management()

File "/usr/local/lib/python2.7/dist-packages/django/db/backends/init.py", line 319, in leave_transaction_management

"Transaction managed block ended with pending COMMIT/ROLLBACK")

TransactionManagementError: Transaction managed block ended with pending COMMIT/ROLLBACK

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Ran 0 tests in 0.084s

FAILED (errors=1)
Destroying test database for alias 'default'...