Fix #3: Don't treat unhandled event types as errors

If an unknown event is received on the event stream, for example if a
new event has been added in a later version of Gerrit, do not raise
an error.  Instead, generate an "UnhandledEvent" event.

Change-Id: Ia1902bf4a54883011b7ad3e004f58a2ba8739b21

3 files changed, 22 insertions, 4 deletions

diff --git a/pygerrit/events.py b/pygerrit/events.py
index 76f1c86..8cf44cd 100644
--- a/pygerrit/events.py
+++ b/pygerrit/events.py
@@ -57,15 +57,14 @@ class GerritEventFactory(object):
         """ Create a new event instance.
 
         Return an instance of the `GerritEvent` subclass from `json_data`
-        Raise GerritError if `json_data` does not contain a `type` key, or
-        no corresponding event is registered.
+        Raise GerritError if `json_data` does not contain a `type` key.
 
         """
         if not "type" in json_data:
             raise GerritError("`type` not in json_data")
         name = json_data["type"]
         if not name in cls._events:
-            raise GerritError("Unknown event: %s" % name)
+            name = 'unhandled-event'
         event = cls._events[name]
         module_name = event[0]
         class_name = event[1]
@@ -82,6 +81,15 @@ class GerritEvent(object):
         self.json = json_data
 
 
+@GerritEventFactory.register("unhandled-event")
+class UnhandledEvent(GerritEvent):
+
+    """ Unknown event type received in json data from Gerrit's event stream. """
+
+    def __init__(self, json_data):
+        super(UnhandledEvent, self).__init__(json_data)
+
+
 @GerritEventFactory.register("patchset-created")
 class PatchsetCreatedEvent(GerritEvent):
 
diff --git a/testdata/unhandled-event.txt b/testdata/unhandled-event.txt
new file mode 100644
index 0000000..6824cc8
--- /dev/null
+++ b/testdata/unhandled-event.txt
@@ -0,0 +1,3 @@
+{"type":"this-event-is-not-handled",
+ "title":"Unhandled event title",
+ "description":"Unhandled event description"}
diff --git a/unittests.py b/unittests.py
index 1588298..358d7f4 100755
--- a/unittests.py
+++ b/unittests.py
@@ -32,7 +32,7 @@ import unittest
 from pygerrit.events import PatchsetCreatedEvent, \
     RefUpdatedEvent, ChangeMergedEvent, CommentAddedEvent, \
     ChangeAbandonedEvent, ChangeRestoredEvent, \
-    DraftPublishedEvent, GerritEventFactory, GerritEvent
+    DraftPublishedEvent, GerritEventFactory, GerritEvent, UnhandledEvent
 from pygerrit.client import GerritClient
 from setup import REQUIRES as setup_requires
 
@@ -58,6 +58,7 @@ def _create_event(name, gerrit):
     data = open(os.path.join("testdata", name + ".txt"))
     json_data = json.loads(data.read().replace("\n", ""))
     gerrit.put_event(json_data)
+    return json_data
 
 
 class TestConsistentDependencies(unittest.TestCase):
@@ -247,6 +248,12 @@ class TestGerritEvents(unittest.TestCase):
         self.assertEquals(event.title, "Event title")
         self.assertEquals(event.description, "Event description")
 
+    def test_unhandled_event(self):
+        json_data = _create_event("unhandled-event", self.gerrit)
+        event = self.gerrit.get_event(False)
+        self.assertTrue(isinstance(event, UnhandledEvent))
+        self.assertEquals(event.json, json_data)
+
     def test_add_duplicate_event(self):
         try:
             @GerritEventFactory.register("user-defined-event")