Fix test from r16678 and r16681 properly for Oracle.

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

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16686 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/modeltests/invalid_models/invalid_models/models.py

@@ -5,7 +5,7 @@
 This example exists purely to point out errors in models.
 """
 
-from django.db import models
+from django.db import connection, models
 
 class FieldErrors(models.Model):
     charfield = models.CharField()
@@ -342,5 +342,8 @@ class PrimaryKeyNull(models.Model):
 invalid_models.nonexistingorderingwithsingleunderscore: "ordering" refers to "does_not_exist", a field that doesn't exist.
 invalid_models.invalidsetnull: 'fk' specifies on_delete=SET_NULL, but cannot be null.
 invalid_models.invalidsetdefault: 'fk' specifies on_delete=SET_DEFAULT, but has no default value.
-invalid_models.primarykeynull: "my_pk_field": Primary key fields cannot have null=True.
+"""
+
+if not connection.features.interprets_empty_strings_as_nulls:
+    model_errors += """invalid_models.primarykeynull: "my_pk_field": Primary key fields cannot have null=True.
 """