From 2bb8c6abaf34c72b27e68a397d228dc2293aa349 Mon Sep 17 00:00:00 2001
From: Roman Vasilets <rvasilets@mirantis.com>
Date: Fri, 11 Dec 2015 19:23:13 +0200
Subject: [PATCH] Make PluginWithSuchNameExists more informative

To find out where are already imported modules of existing plugin
and the new one. We need to provide to the user places of allocations
of this modules.

Change-Id: Ic9e072dfb7f183c2d935b514d2b8df1bd42d3976
---
 rally/common/plugin/plugin.py | 12 +++++++++---
 rally/exceptions.py           |  4 +++-
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/rally/common/plugin/plugin.py b/rally/common/plugin/plugin.py
index 3605307a96..43df1d63c3 100644
--- a/rally/common/plugin/plugin.py
+++ b/rally/common/plugin/plugin.py
@@ -13,6 +13,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import sys
+
 from rally.common.plugin import discover
 from rally.common.plugin import info
 from rally.common.plugin import meta
@@ -142,13 +144,17 @@ class Plugin(meta.MetaMixin, info.InfoMixin):
     @classmethod
     def _set_name_and_namespace(cls, name, namespace):
         try:
-            Plugin.get(name, namespace=namespace)
+            existing_plugin = Plugin.get(name, namespace=namespace)
         except exceptions.PluginNotFound:
             cls._meta_set("name", name)
             cls._meta_set("namespace", namespace)
         else:
-            raise exceptions.PluginWithSuchNameExists(name=name,
-                                                      namespace=namespace)
+            raise exceptions.PluginWithSuchNameExists(
+                name=name, namespace=namespace,
+                existing_path=(
+                    sys.modules[existing_plugin.__module__].__file__),
+                new_path=sys.modules[cls.__module__].__file__
+            )
 
     @classmethod
     def _set_deprecated(cls, reason, rally_version):
diff --git a/rally/exceptions.py b/rally/exceptions.py
index 006ff964c7..f957242642 100644
--- a/rally/exceptions.py
+++ b/rally/exceptions.py
@@ -86,7 +86,9 @@ class PluginNotFound(NotFoundException):
 
 class PluginWithSuchNameExists(RallyException):
     msg_fmt = _("Plugin with such name: %(name)s already exists in "
-                "%(namespace)s namespace")
+                "%(namespace)s namespace. It's module allocates at "
+                "%(existing_path)s. You are trying to add plugin whose module "
+                "allocates at %(new_path)s.")
 
 
 class NoSuchConfigField(NotFoundException):