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
28320	Parallel testing: Please implement a signal or call checks after test DB creation but before cloning it.	László Károlyi	nobody	"Hi,

I tried to reach someone on IRC, but actually it's better to document my issue here, maybe there will be a solution to it eventually.

I'm trying to use the new and shiny parallel testing functionality of Django 1.11, and I've run into problems with it.

So I have functionality implemented on `check` and the `post_migrate` signal, where I conditionally insert stuff into the DB that can't be inserted by fixtures, and also conditionally modify DB fields that can't be done from the ORM. (the latter is basically changing collation on a column)

It seems that the post_migrate signal is run randomly before and after the test creation, and checks are only run *after* the DB is cloned, so I don't have a sufficient point where I can have my logic run.

Monkey-patching has shown that the best solution would be to run `call_command('check')` [https://github.com/django/django/blob/master/django/test/utils.py#L178 here], so basically after `create_test_db` but before `clone_test_db`.

I can quickly add that, but I'm not sure how it could be tested, and what implications it would have, so I'm asking you guys, if you think it's doable and feasible. Because of this right now, I can't use parallel testing."	Cleanup/optimization	closed	Testing framework	1.11	Normal	duplicate			Unreviewed	0	0	0	0	0	0