Moves make_connection to helpers.py and adds unit test for no connect…

…ion in context.

bigquery/tests/unit/helpers.py

@@ -0,0 +1,24 @@
+# Copyright 2018 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+def make_connection(*responses):
+    import google.cloud.bigquery._http
+    import mock
+    from google.cloud.exceptions import NotFound
+
+    mock_conn = mock.create_autospec(google.cloud.bigquery._http.Connection)
+    mock_conn.user_agent = "testing 1.2.3"
+    mock_conn.api_request.side_effect = list(responses) + [NotFound("miss")]
+    return mock_conn

bigquery/tests/unit/test__helpers.py

@@ -782,17 +782,6 @@ def _make_field(field_type, mode="NULLABLE", name="testing", fields=()):
     return SchemaField(name=name, field_type=field_type, mode=mode, fields=fields)
 
 
-def _make_connection(*responses):
-    import google.cloud.bigquery._http
-    import mock
-    from google.cloud.exceptions import NotFound
-
-    mock_conn = mock.create_autospec(google.cloud.bigquery._http.Connection)
-    mock_conn.user_agent = "testing 1.2.3"
-    mock_conn.api_request.side_effect = list(responses) + [NotFound("miss")]
-    return mock_conn
-
-
 class Test_scalar_field_to_json(unittest.TestCase):
     def _call_fut(self, field, value):
         from google.cloud.bigquery._helpers import _scalar_field_to_json