add test for message encode/decode

in corner cases, encode_msg and decode_msg_frame fail

Change-Id: I28b3ddcdce80c7c5b71afe19b11bb73cd761f595
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/22211
Tested-by: JenkinsCodeReview <bjoern_pedersen@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop/protocol/interface/__init__.py

@@ -17,35 +17,26 @@
 #
 # Module authors:
 #   Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
+#   Markus Zolliker <markus.zolliker@psi.ch>
 #
 # *****************************************************************************
 
 import json
 
 EOL = b'\n'
-SPACE = b' '
 
 def encode_msg_frame(action, specifier=None, data=None):
-    """ encode a msg_tripel into an msg_frame, ready to be sent
+    """ encode a msg_triple into an msg_frame, ready to be sent
 
     action (and optional specifier) are str strings,
     data may be an json-yfied python object"""
-    action = action.encode('utf-8')
-    if specifier is None:
-        if data is None:
-            return b''.join((action, EOL))
-        # error_activate might have no specifier
-        specifier = ''
-    specifier = specifier.encode('utf-8')
-    if data:
-        data = json.dumps(data).encode('utf-8')
-        return b''.join((action, SPACE, specifier, SPACE, data, EOL))
-    return b''.join((action, SPACE, specifier, EOL))
+    msg = (action, specifier or '', '' if data is None else json.dumps(data))
+    return ' '.join(msg).strip().encode('utf-8') + EOL
 
 
 def get_msg(_bytes):
     """try to deframe the next msg in (binary) input
-    always return a tupel (msg, remaining_input)
+    always return a tuple (msg, remaining_input)
     msg may also be None
     """
     if EOL not in _bytes:
@@ -54,14 +45,7 @@ def get_msg(_bytes):
 
 
 def decode_msg(msg):
-    """decode the (binary) msg into a (str) msg_tripel"""
-    # check for leading/trailing CR and remove it
-    res = msg.split(b' ', 2)
-    action = res[0].decode('utf-8')
-    if len(res) == 1:
-        return action, None, None
-    specifier = res[1].decode('utf-8')
-    if len(res) == 2:
-        return action, specifier, None
-    data = json.loads(res[2].decode('utf-8'))
-    return action, specifier, data
+    """decode the (binary) msg into a (str) msg_triple"""
+    res = msg.strip().decode('utf-8').split(' ', 2) + ['', '']
+    action, specifier, data = res[0:3]
+    return action, specifier or None, None if data == '' else json.loads(data)

test/test_msg.py

@@ -0,0 +1,52 @@
+#  -*- coding: utf-8 -*-
+# *****************************************************************************
+#
+# This program is free software; you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free Software
+# Foundation; either version 2 of the License, or (at your option) any later
+# version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+# details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program; if not, write to the Free Software Foundation, Inc.,
+# 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+# Module authors:
+#   Markus Zolliker <markus.zolliker@psi.ch>
+#
+# *****************************************************************************
+"""test message encoding and decoding."""
+
+import pytest
+
+from secop.protocol.interface import encode_msg_frame, decode_msg
+import secop.protocol.messages as m
+
+# args are: msg tuple, msg bytes
+MSG = [
+    [(m.DESCRIPTIONREQUEST, None, None), b'describe'],
+    [(m.DESCRIPTIONREPLY, '.', dict(key=0)), b'describing . {"key": 0}'],
+    [(m.ENABLEEVENTSREQUEST, 'module:param', None), b'activate module:param'],
+    [(m.ERRORPREFIX + m.ENABLEEVENTSREQUEST,  None, ['ErrClass', 'text', {}]),
+     b'error_activate  ["ErrClass", "text", {}]'],
+    [(m.COMMANDREQUEST, 'module:stop', None), b'do module:stop'],
+    [(m.COMMANDREPLY, 'module:cmd', ''), b'done module:cmd ""'],
+    [(m.WRITEREQUEST, 'module', 0), b'change module 0'],
+    [(m.WRITEREPLY, 'm:p', 'with space'), b'changed m:p "with space"'],
+    [(m.EVENTREPLY, 'mod:par', [123, dict(t=12.25)]), b'update mod:par [123, {"t": 12.25}]'],
+    [(m.HEARTBEATREQUEST, '0', None), b'ping 0'],
+    [(m.HEARTBEATREPLY, None, [None, dict(t=11.75)]), b'pong  [null, {"t": 11.75}]'],
+    [(m.ERRORPREFIX + m.WRITEREQUEST, 'm:p', ['ErrClass', 'text', dict()]),
+     b'error_change m:p ["ErrClass", "text", {}]'],
+]
+@pytest.mark.parametrize('msg, line', MSG)
+def test_encode(msg, line):
+    assert line + b'\n' == encode_msg_frame(*msg)
+
+@pytest.mark.parametrize('msg, line', MSG)
+def test_decode(msg, line):
+    assert decode_msg(line) == msg