Fix messaging.get_transport caching

If some case get_transport can return a cached transport
even cache=False

This change fixes it and also adds some unit tests for this method

Change-Id: If87cf60d0a25a84dd05f1b84c35f1bcbfeb69b75

1 files changed, 4 insertions, 5 deletions

diff --git a/ceilometer/messaging.py b/ceilometer/messaging.py
index fda4320c..14d842ef 100644
--- a/ceilometer/messaging.py
+++ b/ceilometer/messaging.py
@@ -67,8 +67,9 @@ def setup():
 def get_transport(url=None, optional=False, cache=True):
     """Initialise the oslo.messaging layer."""
     global TRANSPORTS, DEFAULT_URL
-    transport = TRANSPORTS.get(url)
-    if not transport:
+    cache_key = url or DEFAULT_URL
+    transport = TRANSPORTS.get(cache_key)
+    if not transport or not cache:
         try:
             transport = oslo.messaging.get_transport(cfg.CONF, url,
                                                      aliases=_ALIASES)
@@ -79,10 +80,8 @@ def get_transport(url=None, optional=False, cache=True):
                 raise
             return None
         else:
-            if not url:
-                url = DEFAULT_URL
             if cache:
-                TRANSPORTS[url] = transport
+                TRANSPORTS[cache_key] = transport
     return transport