[Tests] Fixes to improve terminal output from unit tests

Add __str__ to WrappedException so that the stacktrace is printed when a
unit test raises a WrappedException.

Change the log output from error to warning in DelugeRPCProtocol.dispatch
when sending back a raised exception on an RPC request.

deluge/core/rpcserver.py

@@ -215,9 +215,9 @@ class DelugeRPCProtocol(DelugeTransferProtocol):
                 ))
             except AttributeError:
                 # This is not a deluge exception (object has no attribute '_args), let's wrap it
-                log.error("An exception occurred while sending RPC_ERROR to "
-                          "client. Wrapping it and resending. Error to "
-                          "send(causing exception goes next):\n%s", formated_tb)
+                log.warning("An exception occurred while sending RPC_ERROR to "
+                            "client. Wrapping it and resending. Error to "
+                            "send(causing exception goes next):\n%s", formated_tb)
                 try:
                     raise WrappedException(str(exceptionValue), exceptionType.__name__, formated_tb)
                 except WrappedException:

deluge/error.py

@@ -43,6 +43,9 @@ class WrappedException(DelugeError):
         self.type = exception_type
         self.traceback = traceback
 
+    def __str__(self):
+        return "%s\n%s" % (self.message, self.traceback)
+
 
 class _ClientSideRecreateError(DelugeError):
     pass

deluge/tests/basetest.py

@@ -16,7 +16,7 @@ class BaseTestCase(unittest.TestCase):
     def setUp(self):  # NOQA
 
         if len(component._ComponentRegistry.components) != 0:
-            warnings.warn("The component._ComponentRegistry.components is not empty on test setup."
+            warnings.warn("The component._ComponentRegistry.components is not empty on test setup.\n"
                           "This is probably caused by another test that didn't clean up after finishing!: %s" %
                           component._ComponentRegistry.components)
         d = maybeDeferred(self.set_up)