Fixed #28626 -- Dropped support for PostgreSQL 9.3.

Thanks Simon Charette for the introspection changes.

tests/postgres_tests/__init__.py

@@ -7,16 +7,6 @@ from django.db.backends.signals import connection_created
 from django.test import TestCase, modify_settings
 
 
-def skipUnlessPG94(test):
-    try:
-        PG_VERSION = connection.pg_version
-    except AttributeError:
-        PG_VERSION = 0
-    if PG_VERSION < 90400:
-        return unittest.skip('PostgreSQL ≥ 9.4 required')(test)
-    return test
-
-
 @unittest.skipUnless(connection.vendor == 'postgresql', "PostgreSQL specific tests")
 class PostgreSQLTestCase(TestCase):
     @classmethod

tests/postgres_tests/migrations/0002_create_test_models.py

@@ -242,7 +242,7 @@ class Migration(migrations.Migration):
                 ('field_custom', JSONField(null=True, blank=True, encoder=DjangoJSONEncoder)),
             ],
             options={
-                'required_db_features': {'has_jsonb_datatype'},
+                'required_db_vendor': 'postgresql',
             },
             bases=(models.Model,),
         ),

tests/postgres_tests/models.py

@@ -140,13 +140,10 @@ class RangeLookupsModel(PostgreSQLModel):
     date = models.DateField(blank=True, null=True)
 
 
-class JSONModel(models.Model):
+class JSONModel(PostgreSQLModel):
     field = JSONField(blank=True, null=True)
     field_custom = JSONField(blank=True, null=True, encoder=DjangoJSONEncoder)
 
-    class Meta:
-        required_db_features = ['has_jsonb_datatype']
-
 
 class ArrayFieldSubclass(ArrayField):
     def __init__(self, *args, **kwargs):

tests/postgres_tests/test_functions.py

@@ -4,7 +4,7 @@ from time import sleep
 
 from django.contrib.postgres.functions import RandomUUID, TransactionNow
 
-from . import PostgreSQLTestCase, skipUnlessPG94
+from . import PostgreSQLTestCase
 from .models import NowTestModel, UUIDTestModel
 
 
@@ -29,7 +29,6 @@ class TestTransactionNow(PostgreSQLTestCase):
         self.assertEqual(m1.when, m2.when)
 
 
-@skipUnlessPG94
 class TestRandomUUID(PostgreSQLTestCase):
 
     def test_random_uuid(self):

tests/postgres_tests/test_introspection.py

@@ -1,7 +1,6 @@
 from io import StringIO
 
 from django.core.management import call_command
-from django.test import skipUnlessDBFeature
 from django.test.utils import modify_settings
 
 from . import PostgreSQLTestCase
@@ -20,7 +19,6 @@ class InspectDBTests(PostgreSQLTestCase):
         for field_output in field_outputs:
             self.assertIn(field_output, output)
 
-    @skipUnlessDBFeature('has_jsonb_datatype')
     def test_json_field(self):
         self.assertFieldsInModel(
             'postgres_tests_jsonmodel',

tests/postgres_tests/test_json.py

@@ -5,7 +5,6 @@ from decimal import Decimal
 from django.core import exceptions, serializers
 from django.core.serializers.json import DjangoJSONEncoder
 from django.forms import CharField, Form, widgets
-from django.test import skipUnlessDBFeature
 from django.utils.html import escape
 
 from . import PostgreSQLTestCase
@@ -18,7 +17,6 @@ except ImportError:
     pass
 
 
-@skipUnlessDBFeature('has_jsonb_datatype')
 class TestSaveLoad(PostgreSQLTestCase):
     def test_null(self):
         instance = JSONModel()
@@ -92,7 +90,6 @@ class TestSaveLoad(PostgreSQLTestCase):
         self.assertEqual(loaded.field_custom, obj_after)
 
 
-@skipUnlessDBFeature('has_jsonb_datatype')
 class TestQuerying(PostgreSQLTestCase):
     @classmethod
     def setUpTestData(cls):
@@ -262,7 +259,6 @@ class TestQuerying(PostgreSQLTestCase):
         self.assertTrue(JSONModel.objects.filter(field__foo__iregex=r'^bAr$').exists())
 
 
-@skipUnlessDBFeature('has_jsonb_datatype')
 class TestSerialization(PostgreSQLTestCase):
     test_data = (
         '[{"fields": {"field": {"a": "b", "c": null}, "field_custom": null}, '