Skipped PostGIS version tests when psycopg2 not installed

Refs #22334. Thanks Tim Graham for spotting the issue.

django/contrib/gis/tests/tests.py

@@ -1,18 +1,24 @@
 import unittest
 
-from django.contrib.gis.db.backends.postgis.operations import PostGISOperations
 from django.core.exceptions import ImproperlyConfigured
 from django.db import ProgrammingError
 
+try:
+    from django.contrib.gis.db.backends.postgis.operations import PostGISOperations
+    HAS_POSTGRES = True
+except ImportError:
+    HAS_POSTGRES = False
 
-class FakeConnection(object):
+
+if HAS_POSTGRES:
+    class FakeConnection(object):
         def __init__(self):
             self.settings_dict = {
                 'NAME': 'test',
             }
 
 
-class FakePostGISOperations(PostGISOperations):
+    class FakePostGISOperations(PostGISOperations):
         def __init__(self, version=None):
             self.version = version
             self.connection = FakeConnection()
@@ -27,6 +33,7 @@ class FakePostGISOperations(PostGISOperations):
                 raise NotImplementedError('This function was not expected to be called')
 
 
+@unittest.skipUnless(HAS_POSTGRES, "The psycopg2 driver is needed for these tests")
 class TestPostgisVersionCheck(unittest.TestCase):
     """
     Tests that the postgis version check parses correctly the version numbers