skip testcase stdlib ConnectionError on Python2

tests/unit/test_retry.py

@@ -19,6 +19,14 @@
 import mock
 
 
+try:
+    ConnectionError
+except NameError:
+    _HAS_STDLIB_CONNECTION_ERROR = False
+else:
+    _HAS_STDLIB_CONNECTION_ERROR = True
+
+
 class Test_should_retry(unittest.TestCase):
     def _call_fut(self, exc):
         from google.cloud.storage import retry
@@ -65,15 +73,12 @@ def test_miss_w_stdlib_error(self):
         exc = ValueError("testing")
         self.assertFalse(self._call_fut(exc))
 
+    @unittest.skipUnless(
+        _HAS_STDLIB_CONNECTION_ERROR, "No builtin 'ConnectionError' in Python 2",
+    )
     def test_w_stdlib_connection_error(self):
-        from google.cloud.storage import retry
-
-        try:
-            exc = ConnectionError()
-            self.assertTrue(self._call_fut(exc))
-            self.assertTrue(ConnectionError in retry._RETRYABLE_TYPES)
-        except NameError:
-            pass
+        exc = ConnectionError()
+        self.assertTrue(self._call_fut(exc))
 
 
 class TestConditionalRetryPolicy(unittest.TestCase):