Fix bytes -> str handling in linux.dig action

CHANGELOG.rst

@@ -51,6 +51,8 @@ Fixed
   up correctly, specifically when specifying a bastion host / jump box. (bug fix) #4973
 
   Contributed by Nick Maludy (@nmaludy Encore Technologies)
+* Fixed a bytes/string encoding bug in the ``linux.dig`` action so it should work on Python 3
+  (bug fix) #4993
 
 * Fixed a bug where a python3 sensor using ssl needs to be monkey patched earlier. See also #4832, #4975 and gevent/gevent#1016 (bug fix) #4976
 

contrib/linux/actions/dig.py

@@ -15,6 +15,7 @@
 # limitations under the License.
 
 import errno
+import locale
 import subprocess
 import random
 import re
@@ -42,12 +43,15 @@ def run(self, rand, count, nameserver, hostname, queryopts):
 
         cmd_args.append(hostname)
 
+        # This function might call getpreferred encoding unless we pass
+        # do_setlocale=False.
+        encoding = locale.getpreferredencoding(do_setlocale=False)
         try:
-            result_list = filter(None, subprocess.Popen(cmd_args,
-                                                        stderr=subprocess.PIPE,
-                                                        stdout=subprocess.PIPE)
-                                 .communicate()[0]
-                                 .split('\n'))
+            result_list = list(filter(None, subprocess.Popen(cmd_args,
+                                                             stderr=subprocess.PIPE,
+                                                             stdout=subprocess.PIPE)
+                                      .communicate()[0].decode(encoding)
+                                      .split('\n')))
 
         # NOTE: Python3 supports the FileNotFoundError, the errono.ENOENT is for py2 compat
         # for Python3:

contrib/linux/tests/test_action_dig.py

@@ -0,0 +1,37 @@
+#!/usr/bin/env python
+
+# Copyright 2020 The StackStorm Developers
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from st2tests.base import BaseActionTestCase
+
+from dig import DigAction
+
+
+class DigActionTestCase(BaseActionTestCase):
+    action_cls = DigAction
+
+    def test_run(self):
+        action = self.get_action_instance()
+
+        # Use the defaults from dig.yaml
+        result = action.run(rand=False, count=0, nameserver=None, hostname='', queryopts='short')
+        self.assertIsInstance(result, list)
+        self.assertEqual(len(result), 0)
+
+        result = action.run(rand=False, count=0, nameserver=None, hostname='google.com',
+                            queryopts='')
+        self.assertIsInstance(result, list)
+        self.assertGreater(len(result), 0)