/common/utils.py py34 incompatibility

Fixes bug found during unit test of get_random_string() method.
For Python3 it is required to encode string as bytes object
before hashing.

Related-blueprint: neutron-python3
Closes-bug: #1502148
Change-Id: I93061a831b45fc8b3ede0211af665ce02f36f38a
(cherry picked from commit 3d54459c29)

neutron/common/utils.py

@@ -312,7 +312,8 @@ def get_random_string(length):
     rndstr = ""
     random.seed(datetime.datetime.now().microsecond)
     while len(rndstr) < length:
-        rndstr += hashlib.sha224(str(random.random())).hexdigest()
+        base_str = str(random.random()).encode('utf-8')
+        rndstr += hashlib.sha224(base_str).hexdigest()
 
     return rndstr[0:length]
 

neutron/tests/unit/common/test_utils.py

@@ -13,6 +13,7 @@
 #    under the License.
 
 import errno
+import re
 
 import eventlet
 import mock
@@ -706,3 +707,12 @@ class TestRoundVal(base.BaseTestCase):
                                 (1, 1.49),
                                 (2, 1.5)):
             self.assertEqual(expected, utils.round_val(value))
+
+
+class TestGetRandomString(base.BaseTestCase):
+    def test_get_random_string(self):
+        length = 127
+        random_string = utils.get_random_string(length)
+        self.assertEqual(length, len(random_string))
+        regex = re.compile('^[0-9a-fA-F]+$')
+        self.assertIsNotNone(regex.match(random_string))