Fix fake driver handling of failure replies

The driver reply() method is actually passed a full sys.exc_info()
tuple.

This was masked in the unit tests because the driver ended up basically
doing:

  raise (ValueError, ValueError, ...)

which caused a new ValueError to be instantiated and the test was
satisified. However, if an exception type has some required arguments,
you'll get a TypeError when this statement attempts to instantiate it
with no arguments.

Change-Id: I4af9c5084954d7b9c5f02cdae3387d17c206985b

oslo/messaging/_drivers/impl_fake.py

@@ -32,6 +32,7 @@ class FakeIncomingMessage(base.IncomingMessage):
 
     def reply(self, reply=None, failure=None, log_failure=True):
         if self._reply_q:
+            failure = failure[1] if failure else None
             self._reply_q.put((reply, failure))
 
 

tests/test_rpc_server.py

@@ -279,12 +279,18 @@ class TestRPCServer(test_utils.BaseTestCase, ServerSetupMixin):
 
         class TestEndpoint(object):
             def ping(self, ctxt, arg):
-                raise ValueError
+                raise ValueError(arg)
 
         server_thread = self._setup_server(transport, TestEndpoint())
         client = self._setup_client(transport)
 
-        self.assertRaises(ValueError, client.call, {}, 'ping', arg='foo')
+        try:
+            client.call({}, 'ping', arg='foo')
+        except Exception as ex:
+            self.assertIsInstance(ex, ValueError)
+            self.assertEquals(ex[0], 'dsfoo')
+        else:
+            self.assertTrue(False)
 
         self._stop_server(client, server_thread)
 
@@ -294,12 +300,18 @@ class TestRPCServer(test_utils.BaseTestCase, ServerSetupMixin):
         class TestEndpoint(object):
             @messaging.expected_exceptions(ValueError)
             def ping(self, ctxt, arg):
-                raise ValueError
+                raise ValueError(arg)
 
         server_thread = self._setup_server(transport, TestEndpoint())
         client = self._setup_client(transport)
 
-        self.assertRaises(ValueError, client.call, {}, 'ping', arg='foo')
+        try:
+            client.call({}, 'ping', arg='foo')
+        except Exception as ex:
+            self.assertIsInstance(ex, ValueError)
+            self.assertEquals(ex[0], 'dsfoo')
+        else:
+            self.assertTrue(False)
 
         self._stop_server(client, server_thread)