Passing Ursula class through instead of importing.

nucypher/characters/base.py

@@ -74,6 +74,7 @@ class Character(Learner):
 
     def __init__(self,
                  domains: Set = None,
+                 node_class: object = None,
                  is_me: bool = True,
                  federated_only: bool = False,
                  checksum_address: str = NO_BLOCKCHAIN_CONNECTION.bool_value(False),
@@ -189,6 +190,7 @@ class Character(Learner):
             Learner.__init__(self,
                              domains=domains,
                              network_middleware=self.network_middleware,
+                             node_class=node_class,
                              *args, **kwargs)
 
         #

nucypher/characters/lawful.py

@@ -119,6 +119,7 @@ class Alice(Character, BlockchainPolicyAuthor):
             self.n = STRANGER_ALICE
 
         Character.__init__(self,
+                           node_class=Ursula,
                            is_me=is_me,
                            federated_only=federated_only,
                            checksum_address=checksum_address,
@@ -831,6 +832,7 @@ class Ursula(Teacher, Character, Worker):
                            abort_on_learning_error=abort_on_learning_error,
                            known_nodes=known_nodes,
                            domains=domains,
+                           node_class=Ursula,
                            **character_kwargs)
 
         #

nucypher/network/nodes.py

@@ -307,6 +307,7 @@ class Learner:
 
     def __init__(self,
                  domains: set,
+                 node_class: object = None,
                  network_middleware: RestMiddleware = __DEFAULT_MIDDLEWARE_CLASS(),
                  start_learning_now: bool = False,
                  learn_on_same_thread: bool = False,
@@ -320,6 +321,7 @@ class Learner:
 
         self.log = Logger("learning-loop")  # type: Logger
 
+        self.node_class = node_class or Teacher
         self.learning_domains = domains
         self.network_middleware = network_middleware
         self.save_metadata = save_metadata