Fix failing tests

Author: sanjay

pymodbus/transaction.py

@@ -171,8 +171,8 @@ def execute(self, request):
                         mbap = self.client.framer.decode_data(response)
                         if (mbap.get('unit') == request.unit_id):
                             break
-                        if ('lenght' in mbap and expected_response_length and
-                            mbap.get('lenght') == expected_response_length):
+                        if ('length' in mbap and expected_response_length and
+                            mbap.get('length') == expected_response_length):
                             break
                         _logger.debug("Retry on invalid - {}".format(retries))
                         if hasattr(self.client, "state"):

test/test_transaction.py

@@ -123,6 +123,13 @@ def testExecute(self):
         response = tm.execute(request)
         self.assertIsInstance(response, ModbusIOException)
 
+        # retry on invalid response
+        tm.retry_on_invalid = True
+        tm._recv = MagicMock(side_effect=iter([b'', b'abcdef', b'deadbe', b'123456']))
+        # tm._transact.side_effect = [(b'', None), (b'abcdef', None)]
+        response = tm.execute(request)
+        self.assertIsInstance(response, ModbusIOException)
+
         # Unable to decode response
         tm._recv = MagicMock(side_effect=ModbusIOException())
         # tm._transact.side_effect = [(b'abcdef', None)]