Close the ChildrenWatch if the node doesn't exist.

This implementation resolves the "NoNodeError" while watching children.

Fix #149.

Author: tonyseek

kazoo/recipe/watchers.py

@@ -315,8 +315,13 @@ def _get_children(self, event=None):
             if self._stopped:
                 return
 
-            children = self._client.retry(self._client.get_children,
-                                          self._path, self._watcher)
+            try:
+                children = self._client.retry(self._client.get_children,
+                                              self._path, self._watcher)
+            except NoNodeError:
+                self._stopped = True
+                return
+
             if not self._watch_established:
                 self._watch_established = True
 

kazoo/tests/test_watchers.py

@@ -171,6 +171,46 @@ def changed(d, stat):
 
         eq_(args, [None, None])
 
+    def test_no_such_node_for_children_watch(self):
+        args = []
+        path = self.path + '/test_no_such_node_for_children_watch'
+        update = threading.Event()
+
+        def changed(children):
+            args.append(children)
+            update.set()
+
+        # watch a node which does not exist
+        children_watch = self.client.ChildrenWatch(path, changed)
+        eq_(update.is_set(), False)
+        eq_(children_watch._stopped, True)
+        eq_(args, [])
+
+        # watch a node which exists
+        self.client.create(path, b'')
+        children_watch = self.client.ChildrenWatch(path, changed)
+        update.wait(3)
+        eq_(args, [[]])
+        update.clear()
+
+        # watch changes
+        self.client.create(path + '/fred', b'')
+        update.wait(3)
+        eq_(args, [[], ['fred']])
+        update.clear()
+
+        # delete children
+        self.client.delete(path + '/fred')
+        update.wait(3)
+        eq_(args, [[], ['fred'], []])
+        update.clear()
+
+        # delete watching
+        self.client.delete(path)
+        time.sleep(1)
+        eq_(update.is_set(), False)
+        eq_(children_watch._stopped, True)
+
     def test_bad_watch_func2(self):
         counter = 0