Adding support for pubsub emulator in system test.

CONTRIBUTING.rst

@@ -242,6 +242,28 @@ Running System Tests
 
 .. _emulators: https://cloud.google.com/sdk/gcloud/reference/beta/emulators/
 
+- To run the ``pubsub`` system tests with an emulator, first start the
+  emulator and take note of the process ID::
+
+   $ gcloud beta emulators pubsub start &
+   [1] 44444
+
+  then determine the environment variables needed to interact with
+  the emulator::
+
+   $ gcloud beta emulators pubsub env-init
+    export PUBSUB_EMULATOR_HOST=localhost:8897
+
+  using these environment variables run the emulator::
+
+   $ DATASTORE_HOST=http://localhost:8897 \
+   >   python system_tests/run_system_test.py \
+   >   --package=pubsub
+
+  and after completion stop the emulator::
+
+   $ kill 44444
+
 Test Coverage
 -------------
 

system_tests/datastore.py

@@ -29,6 +29,7 @@
 # repository root is the current directory.
 from system_tests import clear_datastore
 from system_tests import populate_datastore
+from system_tests.system_test_utils import EmulatorCreds
 
 
 # Isolated namespace so concurrent test runs don't collide.
@@ -45,18 +46,6 @@ class Config(object):
     CLIENT = None
 
 
-class _EmulatorCreds(object):
-    """A mock credential object.
-
-    Used to avoid unnecessary token refreshing or reliance on the network
-    while an emulator is running.
-    """
-
-    @staticmethod
-    def create_scoped_required():
-        return False
-
-
 def clone_client(client):
     # Fool the Client constructor to avoid creating a new connection.
     cloned_client = datastore.Client(project=client.project,
@@ -71,7 +60,7 @@ def setUpModule():
         client_mod.DATASET = TESTS_DATASET
         Config.CLIENT = datastore.Client(namespace=TEST_NAMESPACE)
     else:
-        credentials = _EmulatorCreds()
+        credentials = EmulatorCreds()
         http = httplib2.Http()  # Un-authorized.
         Config.CLIENT = datastore.Client(project=EMULATOR_DATASET,
                                          namespace=TEST_NAMESPACE,

system_tests/pubsub.py

@@ -12,13 +12,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import os
 import time
 
+import httplib2
 import unittest2
 
 from gcloud import _helpers
+from gcloud.environment_vars import PUBSUB_EMULATOR
 from gcloud.environment_vars import TESTS_PROJECT
 from gcloud import pubsub
+from system_tests.system_test_utils import EmulatorCreds
 
 
 class Config(object):
@@ -32,7 +36,13 @@ class Config(object):
 
 def setUpModule():
     _helpers.PROJECT = TESTS_PROJECT
-    Config.CLIENT = pubsub.Client()
+    if os.getenv(PUBSUB_EMULATOR) is None:
+        Config.CLIENT = pubsub.Client()
+    else:
+        credentials = EmulatorCreds()
+        http = httplib2.Http()  # Un-authorized.
+        Config.CLIENT = pubsub.Client(credentials=credentials,
+                                      http=http)
 
 
 class TestPubsub(unittest2.TestCase):

system_tests/system_test_utils.py

@@ -34,6 +34,18 @@
 """
 
 
+class EmulatorCreds(object):
+    """A mock credential object.
+
+    Used to avoid unnecessary token refreshing or reliance on the network
+    while an emulator is running.
+    """
+
+    @staticmethod
+    def create_scoped_required():
+        return False
+
+
 def check_environ(*requirements):
 
     missing = []