protocol: handle 0xb3 automatically

0xb3 is the generic error code (or success, where applicable). Let's handle
those by default so that the rest of the messages only have to care about
replies with message-specific opcodes.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

test/test_messages.py

@@ -379,6 +379,25 @@ class TestProtocolAny(unittest.TestCase):
         msg = p.execute(Interactions.REGISTER_PRESS_BUTTON, uuid=uuid)
         self.assertEqual(msg.uuid, uuid)
 
+    def test_error_invalid_state(self):
+        def _cb(request, requires_reply=True, userdata=None, timeout=5):
+            return NordicData([0xb3, 0x1, 0x1])
+
+        p = Protocol(self.protocol_version, callback=_cb)
+
+        # a "random" collection of requests that we want to check for
+        with self.assertRaises(DeviceError) as cm:
+            p.execute(Interactions.CONNECT, uuid='abcdef123456')
+        self.assertEqual(cm.exception.errorcode, DeviceError.ErrorCode.GENERAL_ERROR)
+
+        with self.assertRaises(DeviceError) as cm:
+            p.execute(Interactions.GET_STROKES)
+        self.assertEqual(cm.exception.errorcode, DeviceError.ErrorCode.GENERAL_ERROR)
+
+        with self.assertRaises(DeviceError) as cm:
+            p.execute(Interactions.SET_MODE, Mode.PAPER)
+        self.assertEqual(cm.exception.errorcode, DeviceError.ErrorCode.GENERAL_ERROR)
+
 
 class TestProtocolSpark(TestProtocolAny):
     protocol_version = ProtocolVersion.SPARK

tuhi/protocol.py

@@ -523,18 +523,16 @@ class Msg(object):
         self._args = args
 
     def _handle_reply(self, reply):
-        '''Override this in the subclass to handle the reply.
+        '''
+        Override this in the subclass to handle the reply. Note that the
+        default 0xb3 message is handled automaticaly, this is only for
+        non-default replies.
 
-        This is the default reply handler that deals with the 0xb3 ACK/Error
-        messages and throws the respective exceptions.
+        No return value, just throw the appropriate exception on failure.
 
         :param reply: A :class:`NordicData` object
         '''
-        if reply.opcode != 0xb3:
-            raise UnexpectedReply(self)
-
-        if reply[0] != 0x00:
-            raise DeviceError(reply[0])
+        raise NotImplementedError(f'{reply} needs customized handling')
 
     def execute(self):
         '''
@@ -554,7 +552,14 @@ class Msg(object):
             if self.reply is None:
                 raise MissingReplyError(self.request)
             try:
-                self._handle_reply(self.reply)
+                # 0xb3 is always handled by us, anything else requires a
+                # custom reply handler
+                if self.reply.opcode == 0xb3:
+                    if self.reply[0] != 0x00:
+                        raise DeviceError(self.reply[0])
+                else:
+                    self._handle_reply(self.reply)
+
                 # no exception? we can assume success
                 self.errorcode = DeviceError.ErrorCode.SUCCESS
             except DeviceError as e: