The test suite no longer runs under Oracle since r16678

[Aymeric Augustin]

​http://ci.django-cms.org/job/Django/database=oracle,python=python2.7/190/console

I don't know why the problem happens only with Oracle, but I reproduce it on my own machines.

[Aymeric Augustin]

In fact, it's certainly a consequence of this:

the Oracle backend coerces the null=True option on fields that have the empty string as a possible value

​https://docs.djangoproject.com/en/dev/ref/databases/#null-and-empty-strings

[Malcolm Tredinnick]

*sigh* Anytime anybody claims Oracle supports SQL, people should feel free to laugh at them. Their NULL handling has been broken forever, in multiple places, and continues to hurt people (like us) trying to write portable SQL. This particular issue is because incorrectly Oracle compares NULL and "" to be equal and the Django backend tries to make things behave uniformly with respect to that.

It would be nice to avoid having to omit that test entirely (since null=True is entirely incorrect when written on a model pk field), but that means checking for explicit null=True versus when Oracle backend adds it implicitly. Alternative is to skip the test for the Oracle backend (which hurts in the multi-db case, I suspect).

[Malcolm Tredinnick]

On the grounds that it can't make things worse, I'm about to commit a one-liner that should fix this by not doing that validation in the "empty string is the same as NULL" case. I'll check the CI server in a day or two when it's had a chance to run the Oracle tests (:-D) and see if that helped.

[Malcolm Tredinnick]

In [16681]:

Modify validity check from r16678 slightly to work with Oracle.

We now skip this particular check on Oracle backends. Change is based on
a backend feature check, so it also works with other backends that may
treat NULL as equal to an empty string.

Fixes #16694 (with luck).

[Aymeric Augustin]

The test suite now runs :) -- the CI server isn't *that* slow; since I've put Oracle's tablespaces in a ramfs it's purely CPU-bound.

However, the test added in r16678 fails under Oracle, because the validation doesn't happen :(

​http://ci.django-cms.org/job/Django/database=oracle,python=python2.7/193/testReport/modeltests.invalid_models.tests/InvalidModelTestCase/test_invalid_models/

Patch attached, tested with Oracle 10g.

NB: I'm reopening this ticket instead of creating a new one because it's a follow-up on the same issue and all the history is on this page.

[Malcolm Tredinnick]

In [16686]:

Fix test from r16678 and r16681 properly for Oracle.

Fixes #16694, with thanks to aagustin for the Oracle testing and
tweaking.