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
21966	Incorrect usage of constraint_checks_disabled in tests	wlodek	nobody	"If a backend implements '''enable/disable_constraint_checking''' (using database SET CONSTRAINTS) some of the tests fail.

The problem comes from the fact that the usage of context manager ""'''constraint_checks_disabled'''"" is based not on the assumptions about how it should work but on the particular implementation for core backends ie. that constraints are checked at transaction commit. 

Because enable/disable_constraint_checking for those backends are empty constraint_checks_disabled context manager does nothing and the tests pass while in fact they should fail.

As I understand ""assumptions about how it should work"" are such that context manager constraint_checks_disabled is for constraints checks something like savepoints for transactions, ie. you can mark a set of statements inside a transaction such the constraints could not be met inside that set but should at the end of set/exit from context manager.

Affected are tests in 'backends', 'serializers_regress', ...

For example in test_disable_constraint_checks_context_manager save inside context manager violates constraints IntegrityError should be raised, it we want to check that it isn't raised we should correct the references before context manager exit.


{{{
try:
    with connection.constraint_checks_disabled():
        a.save()
        a.reporter_id= self.r.id
        a.save()
except IntegrityError:
    self.fail(""IntegrityError should not have occurred."")
}}}

Beside that there is a question why enable/disable_constraint_checking are empty for core backends that could implement that like oracle/postgres? The fact that those backends make use of INITIALY DEFERRED constraints doesn't mean that those must be empty and so test_disable_constraint_checks_context_manager unusable.

"	Bug	closed	Uncategorized	dev	Normal	needsinfo			Unreviewed	0	0	0	0	0	0