BUG23636962: Fix improper error message when creating a Session

This patch changes the output of the error message when connecting
to a MySQL server that does not have X protocol plugin enabled.

Tests were added for regression.

Author: nmariz

lib/mysqlx/protocol.py

@@ -1,5 +1,5 @@
 # MySQL Connector/Python - MySQL driver written in Python.
-# Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2016, 2017, Oracle and/or its affiliates. All rights reserved.
 
 # MySQL Connector/Python is licensed under the terms of the GPLv2
 # <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most
@@ -58,6 +58,9 @@ def read_message(self):
     def _read_message(self):
         hdr = self._stream.read(5)
         msg_len, msg_type = struct.unpack("<LB", hdr)
+        if msg_type == 10:
+            raise ProgrammingError("The connected server does not have the "
+                                   "MySQL X protocol plugin enabled")
         payload = self._stream.read(msg_len - 1)
         msg_type_name = SERVER_MESSAGES.get(msg_type)
         if not msg_type_name:

tests/test_mysqlx_connection.py

@@ -440,6 +440,16 @@ def test_ssl_connection(self):
                         ssl_cert=ssl_cert, ssl_key=ssl_key)
         session = mysqlx.get_session(uri)
 
+    def test_disabled_x_protocol(self):
+        node_session = mysqlx.get_node_session(self.connect_kwargs)
+        res = node_session.sql("SHOW VARIABLES WHERE Variable_name = 'port'") \
+                          .execute().fetch_all()
+        settings = self.connect_kwargs.copy()
+        settings["port"] = res[0][1]  # Lets use the MySQL classic port
+        node_session.close()
+        self.assertRaises(mysqlx.errors.ProgrammingError, mysqlx.get_session,
+                          settings)
+
 
 @unittest.skipIf(tests.MYSQL_VERSION < (5, 7, 12), "XPlugin not compatible")
 class MySQLxNodeSessionTests(tests.MySQLxTests):
@@ -619,3 +629,11 @@ def test_ssl_connection(self):
                         host=config["host"], ssl_ca=ssl_ca,
                         ssl_cert=ssl_cert, ssl_key=ssl_key)
         session = mysqlx.get_node_session(uri)
+
+    def test_disabled_x_protocol(self):
+        res = self.session.sql("SHOW VARIABLES WHERE Variable_name = 'port'") \
+                          .execute().fetch_all()
+        settings = self.connect_kwargs.copy()
+        settings["port"] = res[0][1]  # Lets use the MySQL classic port
+        self.assertRaises(mysqlx.errors.ProgrammingError,
+                          mysqlx.get_node_session, settings)