Fix several shadow tests for PY3

The recent unicode_literals changes broke PY3 when generating a password
using random bytes from pycryto/Cryptodome, this catches the failure to
decode and skips until we get a decodable byte.

salt/utils/pycrypto.py

@@ -5,6 +5,7 @@ Use pycrypto to generate random passwords on the fly.
 
 # Import python libraries
 from __future__ import absolute_import, print_function, unicode_literals
+import logging
 import re
 import string
 import random
@@ -31,25 +32,38 @@ except ImportError:
 
 # Import salt libs
 import salt.utils.stringutils
-from salt.exceptions import SaltInvocationError
+from salt.exceptions import CommandExecutionError, SaltInvocationError
+from salt.ext import six
+
+log = logging.getLogger(__name__)
 
 
 def secure_password(length=20, use_random=True):
     '''
     Generate a secure password.
     '''
-    length = int(length)
-    pw = ''
-    while len(pw) < length:
-        if HAS_RANDOM and use_random:
-            pw += re.sub(
-                r'\W',
-                '',
-                salt.utils.stringutils.to_str(get_random_bytes(1))
-            )
-        else:
-            pw += random.SystemRandom().choice(string.ascii_letters + string.digits)
-    return pw
+    try:
+        length = int(length)
+        pw = ''
+        while len(pw) < length:
+            if HAS_RANDOM and use_random:
+                while True:
+                    try:
+                        char = salt.utils.stringutils.to_str(get_random_bytes(1))
+                        break
+                    except UnicodeDecodeError:
+                        continue
+                pw += re.sub(
+                    salt.utils.stringutils.to_str(r'\W'),
+                    str(),  # future lint: disable=blacklisted-function
+                    char
+                )
+            else:
+                pw += random.SystemRandom().choice(string.ascii_letters + string.digits)
+        return pw
+    except Exception as exc:
+        log.exception('Failed to generate secure passsword')
+        raise CommandExecutionError(six.text_type(exc))
 
 
 def gen_hash(crypt_salt=None, password=None, algorithm='sha512'):

tests/integration/modules/test_shadow.py

@@ -37,6 +37,8 @@ class ShadowModuleTest(ModuleCase):
         '''
         Get current settings
         '''
+        if 'ERROR' in self._password:
+            self.fail('Failed to generate password: {0}'.format(self._password))
         super(ShadowModuleTest, self).setUp()
         os_grain = self.run_function('grains.item', ['kernel'])
         if os_grain['kernel'] not in 'Linux':