[1.9.x] Refs #25745 -- Isolated some postgres array field check tests.

Backport of d95b22bd56 from master

tests/postgres_tests/test_array.py

@@ -4,6 +4,7 @@ import unittest
 import uuid
 
 from django import forms
+from django.apps.registry import Apps
 from django.core import exceptions, serializers, validators
 from django.core.management import call_command
 from django.db import IntegrityError, connection, models
@@ -328,18 +329,28 @@ class TestOtherTypesExactQuerying(PostgreSQLTestCase):
 class TestChecks(PostgreSQLTestCase):
 
     def test_field_checks(self):
+        test_apps = Apps(['postgres_tests'])
+
         class MyModel(PostgreSQLModel):
             field = ArrayField(models.CharField())
 
+            class Meta:
+                apps = test_apps
+
         model = MyModel()
         errors = model.check()
         self.assertEqual(len(errors), 1)
         self.assertEqual(errors[0].id, 'postgres.E001')
 
     def test_invalid_base_fields(self):
+        test_apps = Apps(['postgres_tests'])
+
         class MyModel(PostgreSQLModel):
             field = ArrayField(models.ManyToManyField('postgres_tests.IntegerArrayModel'))
 
+            class Meta:
+                apps = test_apps
+
         model = MyModel()
         errors = model.check()
         self.assertEqual(len(errors), 1)