Use KazooException instead of RuntimeError in TreeCache

#398 (comment)

Author: tonyseek

kazoo/recipe/cache.py

@@ -19,7 +19,7 @@
 import functools
 import operator
 
-from kazoo.exceptions import NoNodeError
+from kazoo.exceptions import NoNodeError, KazooException
 from kazoo.protocol.states import KazooState, EventType
 
 
@@ -63,7 +63,7 @@ def start(self):
         if self._state == self.STATE_LATENT:
             self._state = self.STATE_STARTED
         else:
-            raise RuntimeError('already started')
+            raise KazooException('already started')
 
         self._client.add_listener(self._session_watcher)
         self._client.ensure_path(self._root._path)

kazoo/tests/test_cache.py

@@ -4,6 +4,7 @@
 from nose.tools import eq_, ok_, assert_not_equal, raises
 
 from kazoo.testing import KazooTestCase
+from kazoo.exceptions import KazooException
 from kazoo.recipe.cache import TreeCache, TreeNode, TreeEvent
 
 
@@ -60,7 +61,7 @@ def test_start(self):
         eq_(self.cache._state, TreeCache.STATE_STARTED)
         eq_(self.cache._root._state, TreeNode.STATE_LIVE)
 
-    @raises(RuntimeError)
+    @raises(KazooException)
     def test_start_twice(self):
         self.make_cache()
         self.cache.start()