Remove six

This library no longer supports Python 2, thus usage of six can be
removed. This also removes workaround about pickle library used in
Python 2 only.

Change-Id: I19d298cf0f402d65f0b142dea0bf35cf992332a9

16 files changed, 61 insertions, 100 deletions

diff --git a/taskflow/tests/test_examples.py b/taskflow/tests/test_examples.py
index 6214290..bcb09e1 100644
--- a/taskflow/tests/test_examples.py
+++ b/taskflow/tests/test_examples.py
@@ -34,8 +34,6 @@ import re
 import subprocess
 import sys
 
-import six
-
 from taskflow import test
 
 ROOT_DIR = os.path.abspath(
@@ -118,8 +116,7 @@ class ExampleAdderMeta(type):
         return type.__new__(cls, name, parents, dct)
 
 
-@six.add_metaclass(ExampleAdderMeta)
-class ExamplesTestCase(test.TestCase):
+class ExamplesTestCase(test.TestCase, metaclass=ExampleAdderMeta):
     """Runs the examples, and checks the outputs against expected outputs."""
 
     def _check_example(self, name):
diff --git a/taskflow/tests/unit/action_engine/test_builder.py b/taskflow/tests/unit/action_engine/test_builder.py
index 1bb79b8..72b83ec 100644
--- a/taskflow/tests/unit/action_engine/test_builder.py
+++ b/taskflow/tests/unit/action_engine/test_builder.py
@@ -16,7 +16,6 @@
 
 from automaton import exceptions as excp
 from automaton import runners
-import six
 
 from taskflow.engines.action_engine import builder
 from taskflow.engines.action_engine import compiler
@@ -70,30 +69,30 @@ class BuildersTest(test.TestCase):
             flow, initial_state=st.RUNNING)
 
         it = machine_runner.run_iter(builder.START)
-        prior_state, new_state = six.next(it)
+        prior_state, new_state = next(it)
         self.assertEqual(st.RESUMING, new_state)
         self.assertEqual(0, len(memory.failures))
 
-        prior_state, new_state = six.next(it)
+        prior_state, new_state = next(it)
         self.assertEqual(st.SCHEDULING, new_state)
         self.assertEqual(0, len(memory.failures))
 
-        prior_state, new_state = six.next(it)
+        prior_state, new_state = next(it)
         self.assertEqual(st.WAITING, new_state)
         self.assertEqual(0, len(memory.failures))
 
-        prior_state, new_state = six.next(it)
+        prior_state, new_state = next(it)
         self.assertEqual(st.ANALYZING, new_state)
         self.assertEqual(0, len(memory.failures))
 
-        prior_state, new_state = six.next(it)
+        prior_state, new_state = next(it)
         self.assertEqual(builder.GAME_OVER, new_state)
         self.assertEqual(0, len(memory.failures))
-        prior_state, new_state = six.next(it)
+        prior_state, new_state = next(it)
         self.assertEqual(st.SUCCESS, new_state)
         self.assertEqual(0, len(memory.failures))
 
-        self.assertRaises(StopIteration, six.next, it)
+        self.assertRaises(StopIteration, next, it)
 
     def test_run_iterations_reverted(self):
         flow = lf.Flow("root")
diff --git a/taskflow/tests/unit/jobs/test_redis_job.py b/taskflow/tests/unit/jobs/test_redis_job.py
index 9e6bdc7..320827c 100644
--- a/taskflow/tests/unit/jobs/test_redis_job.py
+++ b/taskflow/tests/unit/jobs/test_redis_job.py
@@ -18,7 +18,6 @@ import time
 from unittest import mock
 
 from oslo_utils import uuidutils
-import six
 import testtools
 
 from taskflow import exceptions as excp
@@ -44,7 +43,7 @@ class RedisJobboardTest(test.TestCase, base.BoardTestMixin):
         namespace = uuidutils.generate_uuid()
         client = ru.RedisClient()
         config = {
-            'namespace': six.b("taskflow-%s" % namespace),
+            'namespace': ("taskflow-%s" % namespace).encode('latin-1'),
         }
         kwargs = {
             'client': client,
diff --git a/taskflow/tests/unit/jobs/test_zk_job.py b/taskflow/tests/unit/jobs/test_zk_job.py
index 527f253..d93f148 100644
--- a/taskflow/tests/unit/jobs/test_zk_job.py
+++ b/taskflow/tests/unit/jobs/test_zk_job.py
@@ -21,7 +21,6 @@ from kazoo.protocol import paths as k_paths
 from kazoo.recipe import watchers
 from oslo_serialization import jsonutils
 from oslo_utils import uuidutils
-import six
 import testtools
 from zake import fake_client
 from zake import utils as zake_utils
@@ -171,7 +170,7 @@ class ZakeJobboardTest(test.TestCase, ZookeeperBoardTestMixin):
             # Forcefully delete the owner from the backend storage to make
             # sure the job becomes unclaimed (this may happen if some admin
             # manually deletes the lock).
-            paths = list(six.iteritems(self.client.storage.paths))
+            paths = list(self.client.storage.paths.items())
             for (path, value) in paths:
                 if path in self.bad_paths:
                     continue
@@ -192,7 +191,7 @@ class ZakeJobboardTest(test.TestCase, ZookeeperBoardTestMixin):
             # Forcefully delete the lock from the backend storage to make
             # sure the job becomes unclaimed (this may happen if some admin
             # manually deletes the lock).
-            paths = list(six.iteritems(self.client.storage.paths))
+            paths = list(self.client.storage.paths.items())
             for (path, value) in paths:
                 if path in self.bad_paths:
                     continue
@@ -215,7 +214,7 @@ class ZakeJobboardTest(test.TestCase, ZookeeperBoardTestMixin):
 
             trashed = []
             jobs = []
-            paths = list(six.iteritems(self.client.storage.paths))
+            paths = list(self.client.storage.paths.items())
             for (path, value) in paths:
                 if path in self.bad_paths:
                     continue
@@ -244,14 +243,14 @@ class ZakeJobboardTest(test.TestCase, ZookeeperBoardTestMixin):
         # Remove paths that got created due to the running process that we are
         # not interested in...
         paths = {}
-        for (path, data) in six.iteritems(self.client.storage.paths):
+        for (path, data) in self.client.storage.paths.items():
             if path in self.bad_paths:
                 continue
             paths[path] = data
 
         # Check the actual data that was posted.
         self.assertEqual(1, len(paths))
-        path_key = list(six.iterkeys(paths))[0]
+        path_key = list(paths.keys())[0]
         self.assertTrue(len(paths[path_key]['data']) > 0)
         self.assertDictEqual({
             'uuid': posted_job.uuid,
diff --git a/taskflow/tests/unit/persistence/test_sql_persistence.py b/taskflow/tests/unit/persistence/test_sql_persistence.py
index 973bf9f..5a1917c 100644
--- a/taskflow/tests/unit/persistence/test_sql_persistence.py
+++ b/taskflow/tests/unit/persistence/test_sql_persistence.py
@@ -20,7 +20,6 @@ import os
 import random
 import tempfile
 
-import six
 import testtools
 
 
@@ -123,8 +122,8 @@ class SqlitePersistenceTest(test.TestCase, base.PersistenceTestMixin):
             self.db_location = None
 
 
-@six.add_metaclass(abc.ABCMeta)
-class BackendPersistenceTestMixin(base.PersistenceTestMixin):
+class BackendPersistenceTestMixin(base.PersistenceTestMixin,
+                                  metaclass=abc.ABCMeta):
     """Specifies a backend type and does required setup and teardown."""
 
     def _get_connection(self):
diff --git a/taskflow/tests/unit/test_engines.py b/taskflow/tests/unit/test_engines.py
index 81f0e08..4454429 100644
--- a/taskflow/tests/unit/test_engines.py
+++ b/taskflow/tests/unit/test_engines.py
@@ -20,7 +20,6 @@ import functools
 import threading
 
 import futurist
-import six
 import testtools
 
 import taskflow.engines
@@ -350,7 +349,7 @@ class EngineLinearFlowTest(utils.EngineTestBase):
             engine_it = engine.run_iter()
             while True:
                 try:
-                    engine_state = six.next(engine_it)
+                    engine_state = next(engine_it)
                     if engine_state not in engine_states:
                         engine_states[engine_state] = 1
                     else:
@@ -1318,7 +1317,7 @@ class EngineGraphConditionalFlowTest(utils.EngineTestBase):
     def test_graph_flow_conditional_history(self):
 
         def even_odd_decider(history, allowed):
-            total = sum(six.itervalues(history))
+            total = sum(history.values())
             if total == allowed:
                 return True
             return False
diff --git a/taskflow/tests/unit/test_exceptions.py b/taskflow/tests/unit/test_exceptions.py
index c542ae8..4c20f7c 100644
--- a/taskflow/tests/unit/test_exceptions.py
+++ b/taskflow/tests/unit/test_exceptions.py
@@ -16,9 +16,6 @@
 
 import string
 
-import six
-import testtools
-
 from taskflow import exceptions as exc
 from taskflow import test
 
@@ -109,7 +106,6 @@ class TestExceptions(test.TestCase):
         ex = exc.TaskFlowException("Broken")
         self.assertRaises(ValueError, ex.pformat, indent=-100)
 
-    @testtools.skipIf(not six.PY3, 'py3.x is not available')
     def test_raise_with_cause(self):
         capture = None
         try:
diff --git a/taskflow/tests/unit/test_failure.py b/taskflow/tests/unit/test_failure.py
index 217f1b3..1c25ac7 100644
--- a/taskflow/tests/unit/test_failure.py
+++ b/taskflow/tests/unit/test_failure.py
@@ -14,12 +14,10 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import pickle
 import sys
 
 from oslo_utils import encodeutils
-import six
-from six.moves import cPickle as pickle
-import testtools
 
 from taskflow import exceptions
 from taskflow import test
@@ -338,23 +336,16 @@ class NonAsciiExceptionsTestCase(test.TestCase):
         fail = failure.Failure.from_exception(excp)
         self.assertEqual(encodeutils.exception_to_unicode(excp),
                          fail.exception_str)
-        # This is slightly different on py2 vs py3... due to how
-        # __str__ or __unicode__ is called and what is expected from
-        # both...
-        if six.PY2:
-            msg = encodeutils.exception_to_unicode(excp)
-            expected = 'Failure: ValueError: %s' % msg.encode('utf-8')
-        else:
-            expected = u'Failure: ValueError: \xc8'
+        expected = u'Failure: ValueError: \xc8'
         self.assertEqual(expected, str(fail))
 
     def test_exception_non_ascii_unicode(self):
         hi_ru = u'привет'
         fail = failure.Failure.from_exception(ValueError(hi_ru))
         self.assertEqual(hi_ru, fail.exception_str)
-        self.assertIsInstance(fail.exception_str, six.text_type)
+        self.assertIsInstance(fail.exception_str, str)
         self.assertEqual(u'Failure: ValueError: %s' % hi_ru,
-                         six.text_type(fail))
+                         str(fail))
 
     def test_wrapped_failure_non_ascii_unicode(self):
         hi_cn = u'嗨'
@@ -364,7 +355,7 @@ class NonAsciiExceptionsTestCase(test.TestCase):
         wrapped_fail = exceptions.WrappedFailure([fail])
         expected_result = (u"WrappedFailure: "
                            "[Failure: ValueError: %s]" % (hi_cn))
-        self.assertEqual(expected_result, six.text_type(wrapped_fail))
+        self.assertEqual(expected_result, str(wrapped_fail))
 
     def test_failure_equality_with_non_ascii_str(self):
         bad_string = chr(200)
@@ -379,7 +370,6 @@ class NonAsciiExceptionsTestCase(test.TestCase):
         self.assertEqual(fail, copied)
 
 
-@testtools.skipIf(not six.PY3, 'this test only works on python 3.x')
 class FailureCausesTest(test.TestCase):
 
     @classmethod
@@ -392,7 +382,7 @@ class FailureCausesTest(test.TestCase):
             cls._raise_many(messages)
             raise e
         except RuntimeError as e1:
-            six.raise_from(e, e1)
+            raise e from e1
 
     def test_causes(self):
         f = None
@@ -467,7 +457,7 @@ class FailureCausesTest(test.TestCase):
                 self._raise_many(["Still still not working",
                                   "Still not working", "Not working"])
             except RuntimeError as e:
-                six.raise_from(e, None)
+                raise e from None
         except RuntimeError:
             f = failure.Failure()
 
diff --git a/taskflow/tests/unit/test_listeners.py b/taskflow/tests/unit/test_listeners.py
index 3e2f880..b14f7f2 100644
--- a/taskflow/tests/unit/test_listeners.py
+++ b/taskflow/tests/unit/test_listeners.py
@@ -21,7 +21,6 @@ import time
 
 from oslo_serialization import jsonutils
 from oslo_utils import reflection
-import six
 from zake import fake_client
 
 import taskflow.engines
@@ -111,7 +110,7 @@ class TestClaimListener(test.TestCase, EngineMakerMixin):
         children = self.client.storage.get_children("/taskflow",
                                                     only_direct=False)
         removed = 0
-        for p, data in six.iteritems(children):
+        for p, data in children.items():
             if p.endswith(".lock"):
                 self.client.storage.pop(p)
                 removed += 1
@@ -121,7 +120,7 @@ class TestClaimListener(test.TestCase, EngineMakerMixin):
         children = self.client.storage.get_children("/taskflow",
                                                     only_direct=False)
         altered = 0
-        for p, data in six.iteritems(children):
+        for p, data in children.items():
             if p.endswith(".lock"):
                 self.client.set(p, misc.binary_encode(
                     jsonutils.dumps({'owner': new_owner})))
diff --git a/taskflow/tests/unit/test_types.py b/taskflow/tests/unit/test_types.py
index fd97cd6..eca26cd 100644
--- a/taskflow/tests/unit/test_types.py
+++ b/taskflow/tests/unit/test_types.py
@@ -15,7 +15,7 @@
 #    under the License.
 
 import networkx as nx
-from six.moves import cPickle as pickle
+import pickle
 
 from taskflow import test
 from taskflow.types import graph
diff --git a/taskflow/tests/unit/test_utils.py b/taskflow/tests/unit/test_utils.py
index 72bddd2..168e517 100644
--- a/taskflow/tests/unit/test_utils.py
+++ b/taskflow/tests/unit/test_utils.py
@@ -20,7 +20,6 @@ import random
 import string
 import time
 
-import six
 import testscenarios
 
 from taskflow import test
@@ -241,7 +240,7 @@ class TestCountdownIter(test.TestCase):
 
     def test_invalid_decr(self):
         it = misc.countdown_iter(10, -1)
-        self.assertRaises(ValueError, six.next, it)
+        self.assertRaises(ValueError, next, it)
 
 
 class TestMergeUri(test.TestCase):
diff --git a/taskflow/tests/unit/test_utils_binary.py b/taskflow/tests/unit/test_utils_binary.py
index 773f389..0ba930f 100644
--- a/taskflow/tests/unit/test_utils_binary.py
+++ b/taskflow/tests/unit/test_utils_binary.py
@@ -14,24 +14,19 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import six
-
 from taskflow import test
 from taskflow.utils import misc
 
 
 def _bytes(data):
-    if six.PY3:
-        return data.encode(encoding='utf-8')
-    else:
-        return data
+    return data.encode(encoding='utf-8')
 
 
 class BinaryEncodeTest(test.TestCase):
 
     def _check(self, data, expected_result):
         result = misc.binary_encode(data)
-        self.assertIsInstance(result, six.binary_type)
+        self.assertIsInstance(result, bytes)
         self.assertEqual(expected_result, result)
 
     def test_simple_binary(self):
@@ -50,7 +45,7 @@ class BinaryEncodeTest(test.TestCase):
 
     def test_unicode_other_encoding(self):
         result = misc.binary_encode(u'mañana', 'latin-1')
-        self.assertIsInstance(result, six.binary_type)
+        self.assertIsInstance(result, bytes)
         self.assertEqual(u'mañana'.encode('latin-1'), result)
 
 
@@ -58,7 +53,7 @@ class BinaryDecodeTest(test.TestCase):
 
     def _check(self, data, expected_result):
         result = misc.binary_decode(data)
-        self.assertIsInstance(result, six.text_type)
+        self.assertIsInstance(result, str)
         self.assertEqual(expected_result, result)
 
     def test_simple_text(self):
@@ -78,7 +73,7 @@ class BinaryDecodeTest(test.TestCase):
     def test_unicode_other_encoding(self):
         data = u'mañana'.encode('latin-1')
         result = misc.binary_decode(data, 'latin-1')
-        self.assertIsInstance(result, six.text_type)
+        self.assertIsInstance(result, str)
         self.assertEqual(u'mañana', result)
 
 
@@ -94,7 +89,7 @@ class DecodeJsonTest(test.TestCase):
 
     def test_handles_invalid_unicode(self):
         self.assertRaises(ValueError, misc.decode_json,
-                          six.b('{"\xf1": 1}'))
+                          '{"\xf1": 1}'.encode('latin-1'))
 
     def test_handles_bad_json(self):
         self.assertRaises(ValueError, misc.decode_json,
diff --git a/taskflow/tests/unit/test_utils_iter_utils.py b/taskflow/tests/unit/test_utils_iter_utils.py
index 4a5ff4b..c4109d8 100644
--- a/taskflow/tests/unit/test_utils_iter_utils.py
+++ b/taskflow/tests/unit/test_utils_iter_utils.py
@@ -16,9 +16,6 @@
 
 import string
 
-import six
-from six.moves import range as compat_range
-
 from taskflow import test
 from taskflow.utils import iter_utils
 
@@ -46,22 +43,22 @@ class IterUtilsTest(test.TestCase):
 
     def test_generate_delays(self):
         it = iter_utils.generate_delays(1, 60)
-        self.assertEqual(1, six.next(it))
-        self.assertEqual(2, six.next(it))
-        self.assertEqual(4, six.next(it))
-        self.assertEqual(8, six.next(it))
-        self.assertEqual(16, six.next(it))
-        self.assertEqual(32, six.next(it))
-        self.assertEqual(60, six.next(it))
-        self.assertEqual(60, six.next(it))
+        self.assertEqual(1, next(it))
+        self.assertEqual(2, next(it))
+        self.assertEqual(4, next(it))
+        self.assertEqual(8, next(it))
+        self.assertEqual(16, next(it))
+        self.assertEqual(32, next(it))
+        self.assertEqual(60, next(it))
+        self.assertEqual(60, next(it))
 
     def test_generate_delays_custom_multiplier(self):
         it = iter_utils.generate_delays(1, 60, multiplier=4)
-        self.assertEqual(1, six.next(it))
-        self.assertEqual(4, six.next(it))
-        self.assertEqual(16, six.next(it))
-        self.assertEqual(60, six.next(it))
-        self.assertEqual(60, six.next(it))
+        self.assertEqual(1, next(it))
+        self.assertEqual(4, next(it))
+        self.assertEqual(16, next(it))
+        self.assertEqual(60, next(it))
+        self.assertEqual(60, next(it))
 
     def test_generate_delays_bad(self):
         self.assertRaises(ValueError, iter_utils.generate_delays, -1, -1)
@@ -99,7 +96,7 @@ class IterUtilsTest(test.TestCase):
         self.assertRaises(ValueError, iter_utils.fill, 2, 2)
 
     def test_fill_many_empty(self):
-        result = list(iter_utils.fill(compat_range(0, 50), 500))
+        result = list(iter_utils.fill(range(0, 50), 500))
         self.assertEqual(450, sum(1 for x in result if x is None))
         self.assertEqual(50, sum(1 for x in result if x is not None))
 
@@ -134,10 +131,10 @@ class IterUtilsTest(test.TestCase):
     def test_count(self):
         self.assertEqual(0, iter_utils.count([]))
         self.assertEqual(1, iter_utils.count(['a']))
-        self.assertEqual(10, iter_utils.count(compat_range(0, 10)))
-        self.assertEqual(1000, iter_utils.count(compat_range(0, 1000)))
-        self.assertEqual(0, iter_utils.count(compat_range(0)))
-        self.assertEqual(0, iter_utils.count(compat_range(-1)))
+        self.assertEqual(10, iter_utils.count(range(0, 10)))
+        self.assertEqual(1000, iter_utils.count(range(0, 1000)))
+        self.assertEqual(0, iter_utils.count(range(0)))
+        self.assertEqual(0, iter_utils.count(range(-1)))
 
     def test_bad_while_is_not(self):
         self.assertRaises(ValueError, iter_utils.while_is_not, 2, 'a')
diff --git a/taskflow/tests/unit/worker_based/test_server.py b/taskflow/tests/unit/worker_based/test_server.py
index 5380204..2261628 100644
--- a/taskflow/tests/unit/worker_based/test_server.py
+++ b/taskflow/tests/unit/worker_based/test_server.py
@@ -14,8 +14,6 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import six
-
 from taskflow.engines.worker_based import endpoint as ep
 from taskflow.engines.worker_based import protocol as pr
 from taskflow.engines.worker_based import server
@@ -143,7 +141,7 @@ class TestServer(test.MockTestCase):
             (self.task.name, self.task.name, 'revert',
              dict(arguments=self.task_args,
                   failures=dict((i, utils.FailureMatcher(f))
-                                for i, f in six.iteritems(failures)))),
+                                for i, f in failures.items()))),
             (task_cls, task_name, action, task_args))
 
     @mock.patch("taskflow.engines.worker_based.server.LOG.critical")
diff --git a/taskflow/tests/unit/worker_based/test_worker.py b/taskflow/tests/unit/worker_based/test_worker.py
index 0e49a56..3b068a0 100644
--- a/taskflow/tests/unit/worker_based/test_worker.py
+++ b/taskflow/tests/unit/worker_based/test_worker.py
@@ -14,8 +14,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import io
 from oslo_utils import reflection
-import six
 
 from taskflow.engines.worker_based import endpoint
 from taskflow.engines.worker_based import worker
@@ -66,7 +66,7 @@ class TestWorker(test.MockTestCase):
         self.assertEqual(master_mock_calls, self.master_mock.mock_calls)
 
     def test_banner_writing(self):
-        buf = six.StringIO()
+        buf = io.StringIO()
         w = self.worker()
         w.run(banner_writer=buf.write)
         w.wait()
diff --git a/taskflow/tests/utils.py b/taskflow/tests/utils.py
index 58cd9ab..6c2f13a 100644
--- a/taskflow/tests/utils.py
+++ b/taskflow/tests/utils.py
@@ -21,7 +21,6 @@ import time
 
 from oslo_utils import timeutils
 import redis
-import six
 
 from taskflow import exceptions
 from taskflow.listeners import capturing
@@ -137,7 +136,7 @@ class GiveBackRevert(task.Task):
         result = kwargs.get('result')
         # If this somehow fails, timeout, or other don't send back a
         # valid result...
-        if isinstance(result, six.integer_types):
+        if isinstance(result, int):
             return result + 1
 
 
@@ -153,12 +152,8 @@ class LongArgNameTask(task.Task):
         return long_arg_name
 
 
-if six.PY3:
-    RUNTIME_ERROR_CLASSES = ['RuntimeError', 'Exception',
-                             'BaseException', 'object']
-else:
-    RUNTIME_ERROR_CLASSES = ['RuntimeError', 'StandardError', 'Exception',
-                             'BaseException', 'object']
+RUNTIME_ERROR_CLASSES = ['RuntimeError', 'Exception', 'BaseException',
+                         'object']
 
 
 class ProvidesRequiresTask(task.Task):
@@ -410,11 +405,11 @@ class WaitForOneFromTask(ProgressingTask):
 
     def __init__(self, name, wait_for, wait_states, **kwargs):
         super(WaitForOneFromTask, self).__init__(name, **kwargs)
-        if isinstance(wait_for, six.string_types):
+        if isinstance(wait_for, str):
             self.wait_for = [wait_for]
         else:
             self.wait_for = wait_for
-        if isinstance(wait_states, six.string_types):
+        if isinstance(wait_states, str):
             self.wait_states = [wait_states]
         else:
             self.wait_states = wait_states