bots: Require bots_details in ExternalBotHandler.

This parameter was defaulting to a dictionary, which is
a classic Python pitfall.

zulip_bots/zulip_bots/lib.py

@@ -83,7 +83,7 @@ class StateHandler(object):
         return key in self.state_
 
 class ExternalBotHandler(object):
-    def __init__(self, client, root_dir, bot_details={}):
+    def __init__(self, client, root_dir, bot_details):
         # type: (Client, str, Dict[str, Any]) -> None
         # Only expose a subset of our Client's functionality
         try:

zulip_bots/zulip_bots/test_lib.py

@@ -44,7 +44,7 @@ class BotTestCaseBase(TestCase):
         # Mocking ExternalBotHandler
         self.patcher = patch('zulip_bots.lib.ExternalBotHandler', autospec=True)
         self.MockClass = self.patcher.start()
-        self.mock_bot_handler = self.MockClass(None, None)
+        self.mock_bot_handler = self.MockClass(None, None, None)
         self.mock_client = MagicMock()
         self.mock_client.get_storage.return_value = {'result': 'success', 'state': {}}
         self.mock_client.update_storage.return_value = {'result': 'success'}

zulip_botserver/zulip_botserver/server.py

@@ -54,7 +54,7 @@ def load_bot_handlers():
         try:
             bot_dir = os.path.join(os.path.dirname(os.path.abspath(__file__)),
                                    'bots', bot)
-            bot_handlers[bot] = ExternalBotHandler(client, bot_dir)
+            bot_handlers[bot] = ExternalBotHandler(client, bot_dir, bot_details={})
         except SystemExit:
             return BadRequest("Cannot fetch user profile for bot {}, make sure you have set up the flaskbotrc "
                               "file correctly.".format(bot))