Moving _get_pb_property_value from bigtable into core.

Doing this so that we can factor out `_has_field` and use it across
packages. This is because `HasField()` works differently in
`proto3` and we use this behavior from time to time.

Author: dhermes

gcloud/_helpers.py

@@ -322,6 +322,45 @@ def _to_bytes(value, encoding='ascii'):
         raise TypeError('%r could not be converted to bytes' % (value,))
 
 
+def _has_field(message_pb, property_name):
+    """Determine if a field is set on a protobuf.
+
+    :type message_pb: :class:`google.protobuf.message.Message`
+    :param message_pb: The message to check for ``property_name``.
+
+    :type property_name: str
+    :param property_name: The property value to check against.
+
+    :rtype: bool
+    :returns: Flag indicating if ``property_name`` is set on ``message_pb``.
+    """
+    # NOTE: As of proto3, HasField() only works for message fields, not for
+    #       singular (non-message) fields.
+    all_fields = set([field.name for field in message_pb._fields])
+    return property_name in all_fields
+
+
+def _get_pb_property_value(message_pb, property_name):
+    """Return a message field value.
+
+    :type message_pb: :class:`google.protobuf.message.Message`
+    :param message_pb: The message to check for ``property_name``.
+
+    :type property_name: str
+    :param property_name: The property value to check against.
+
+    :rtype: object
+    :returns: The value of ``property_name`` set on ``message_pb``.
+    :raises: :class:`ValueError <exceptions.ValueError>` if the result returned
+             from the ``message_pb`` does not contain the ``property_name``
+             value.
+    """
+    if _has_field(message_pb, property_name):
+        return getattr(message_pb, property_name)
+    else:
+        raise ValueError('Message does not contain %s.' % (property_name,))
+
+
 try:
     from pytz import UTC  # pylint: disable=unused-import,wrong-import-position
 except ImportError:

gcloud/bigtable/cluster.py

@@ -19,6 +19,7 @@
 import re
 
 from gcloud._helpers import _EPOCH
+from gcloud._helpers import _get_pb_property_value
 from gcloud.bigtable._generated import bigtable_cluster_data_pb2 as data_pb2
 from gcloud.bigtable._generated import (
     bigtable_cluster_service_messages_pb2 as messages_pb2)
@@ -47,30 +48,6 @@
 }
 
 
-def _get_pb_property_value(message_pb, property_name):
-    """Return a message field value.
-
-    :type message_pb: :class:`google.protobuf.message.Message`
-    :param message_pb: The message to check for ``property_name``.
-
-    :type property_name: str
-    :param property_name: The property value to check against.
-
-    :rtype: object
-    :returns: The value of ``property_name`` set on ``message_pb``.
-    :raises: :class:`ValueError <exceptions.ValueError>` if the result returned
-             from the ``message_pb`` does not contain the ``property_name``
-             value.
-    """
-    # Make sure `property_name` is set on the response.
-    # NOTE: As of proto3, HasField() only works for message fields, not for
-    #       singular (non-message) fields.
-    all_fields = set([field.name for field in message_pb._fields])
-    if property_name not in all_fields:
-        raise ValueError('Message does not contain %s.' % (property_name,))
-    return getattr(message_pb, property_name)
-
-
 def _prepare_create_request(cluster):
     """Creates a protobuf request for a CreateCluster request.
 

gcloud/bigtable/test_cluster.py

@@ -631,28 +631,6 @@ def test_list_tables_failure_name_bad_before(self):
             self._list_tables_helper(table_id, table_name=bad_table_name)
 
 
-class Test__get_pb_property_value(unittest2.TestCase):
-
-    def _callFUT(self, message_pb, property_name):
-        from gcloud.bigtable.cluster import _get_pb_property_value
-        return _get_pb_property_value(message_pb, property_name)
-
-    def test_it(self):
-        from gcloud.bigtable._generated import (
-            bigtable_cluster_data_pb2 as data_pb2)
-        serve_nodes = 119
-        cluster_pb = data_pb2.Cluster(serve_nodes=serve_nodes)
-        result = self._callFUT(cluster_pb, 'serve_nodes')
-        self.assertEqual(result, serve_nodes)
-
-    def test_with_value_unset_on_pb(self):
-        from gcloud.bigtable._generated import (
-            bigtable_cluster_data_pb2 as data_pb2)
-        cluster_pb = data_pb2.Cluster()
-        with self.assertRaises(ValueError):
-            self._callFUT(cluster_pb, 'serve_nodes')
-
-
 class Test__prepare_create_request(unittest2.TestCase):
 
     def _callFUT(self, cluster):

gcloud/test__helpers.py

@@ -409,6 +409,28 @@ def test_with_nonstring_type(self):
         self.assertRaises(TypeError, self._callFUT, value)
 
 
+class Test__get_pb_property_value(unittest2.TestCase):
+
+    def _callFUT(self, message_pb, property_name):
+        from gcloud._helpers import _get_pb_property_value
+        return _get_pb_property_value(message_pb, property_name)
+
+    def test_it(self):
+        from gcloud.bigtable._generated import (
+            bigtable_cluster_data_pb2 as data_pb2)
+        serve_nodes = 119
+        cluster_pb = data_pb2.Cluster(serve_nodes=serve_nodes)
+        result = self._callFUT(cluster_pb, 'serve_nodes')
+        self.assertEqual(result, serve_nodes)
+
+    def test_with_value_unset_on_pb(self):
+        from gcloud.bigtable._generated import (
+            bigtable_cluster_data_pb2 as data_pb2)
+        cluster_pb = data_pb2.Cluster()
+        with self.assertRaises(ValueError):
+            self._callFUT(cluster_pb, 'serve_nodes')
+
+
 class _AppIdentity(object):
 
     def __init__(self, app_id):