conditionally disable a part of a test that can't pass on 32-bit systems

src/ZODB/tests/testConnection.py

@@ -17,6 +17,7 @@ from __future__ import print_function
 import doctest
 import re
 import six
+import sys
 import unittest
 
 import transaction
@@ -1140,7 +1141,8 @@ class EstimatedSizeTests(ZODB.tests.util.TestCase):
         # ... on connectionB
         conn = db.open()
         self.assertEqual(conn._cache.cache_size_bytes, expected)
-        # test huge (larger than 4 byte) size limit
+        # test huge (larger than 4 byte) size limit (if possible)
+        if sys.maxsize > (0x1 << 33):
             db = databaseFromString("<zodb>\n"
                                     "  cache-size-bytes 8GB\n"
                                     "  <mappingstorage />\n"