#25746: Isolate inlined test models
------------------------------------------------+------------------------
Reporter: charettes | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Testing framework | Version: master
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
------------------------------------------------+------------------------
Many test in Django's own test suite inline model definition in order to
prevent table creation or simply isolate them.
Unfortunately most of these model don't explicitly declare an explicit
`apps` and end up being registered to the global `apps` instance. This has
three downsides:
1. The call to `register_model` busts the `apps` and registered models
(1k+) `_meta` cache. I didn't run any benchmark here but I suspect this
slow down things a bit.
2. If a model is already registered for the specified
`app_label.ModelName` (see the `schema` issue detailed in #25745) a
`RuntimeWarning` is raised.
3. If no model is registered for this particular `app_label.ModelName` any
future call to `migrate` will end up creating the table since we don't
have explicit migration defined for the test apps.
To prevent the enumerated issues the inlined models should use a per-test
isolated registry. Examples of such a pattern can be found on this
[https://github.com/django/django/pull/5613 PR].
e.g.
{{{#!python
def test_foo(self):
test_apps = Apps(['test_app'])
class Foo(models.Model):
class Meta:
apps = test_apps
}}}
In order to reduce the boiler plate required to achieve isolation I
suggest introducing a test decorator/context manager that register models
declared in it's body in an isolated `Apps()` instance.
e.g.
{{{#!python
@isolate_apps('test_app', 'test_app_2')
def test_foo(self):
class Foo(models.Model):
pass
with isolate_apps('test_app3') as apps:
class Bar(models.Model):
class Meta:
app_label = 'test_app3'
assert Bar is apps.get_model('test_app3', 'Bar')
}}}
This would also make fixing the actual and future isolation problems quite
easy by simply decorating the faulty test.
--
Ticket URL: <https://code.djangoproject.com/ticket/25746>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
--
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-updates/052.92830947c9394315c54a5f83e925feb0%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.
