Remove six dependency

We run on Python 3 only, time to remove six dependency

Also fix l-c for new pip-resolver and move pep8 deps
in tox.ini to avoid conflicts.

And since we're here, update pre-commit config to support correct
hacking version.

Change-Id: Ibbe733c4be37d1a9dd9149d491591ef2e50dad6a

.pre-commit-config.yaml

@@ -9,7 +9,7 @@ default_language_version:
 
 repos:
   - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: ebc15addedad713c86ef18ae9632c88e187dd0af  # v3.1.0
+    rev: 9136088a246768144165fcc3ecc3d31bb686920a # v3.3.0
     hooks:
       - id: trailing-whitespace
       # Replaces or checks mixed line ending
@@ -28,8 +28,8 @@ repos:
       - id: check-yaml
         files: .*\.(yaml|yml)$
   - repo: https://gitlab.com/pycqa/flake8
-    rev: 181bb46098dddf7e2d45319ea654b4b4d58c2840 # 3.8.3
+    rev: fb91b994ed4adf4f2b4890e7bdba82f57e3a81df # 3.8.4
     hooks:
       - id: flake8
         additional_dependencies:
-          - hacking>=3.0.1,<3.1.0
+          - hacking>=3.1.0,<4.0

automaton/machines.py

@@ -15,7 +15,6 @@
 import collections
 
 import prettytable
-import six
 
 from automaton import _utils as utils
 from automaton import exceptions as excp
@@ -54,9 +53,9 @@ def _convert_to_states(state_space):
 
 def _orderedkeys(data, sort=True):
     if sort:
-        return sorted(six.iterkeys(data))
+        return sorted(data)
     else:
-        return list(six.iterkeys(data))
+        return list(data)
 
 
 class _Jump(object):
@@ -178,10 +177,10 @@ class FiniteMachine(object):
         if state in self._states:
             raise excp.Duplicate("State '%s' already defined" % state)
         if on_enter is not None:
-            if not six.callable(on_enter):
+            if not callable(on_enter):
                 raise ValueError("On enter callback must be callable")
         if on_exit is not None:
-            if not six.callable(on_exit):
+            if not callable(on_exit):
                 raise ValueError("On exit callback must be callable")
         self._states[state] = {
             'terminal': bool(terminal),
@@ -225,7 +224,7 @@ class FiniteMachine(object):
         if state not in self._states:
             raise excp.NotFound("Can not add a reaction to event '%s' for an"
                                 " undefined state '%s'" % (event, state))
-        if not six.callable(reaction):
+        if not callable(reaction):
             raise ValueError("Reaction callback must be callable")
         if event not in self._states[state]['reactions']:
             self._states[state]['reactions'][event] = (reaction, args, kwargs)
@@ -380,19 +379,19 @@ class FiniteMachine(object):
     @property
     def states(self):
         """Returns the state names."""
-        return list(six.iterkeys(self._states))
+        return list(self._states)
 
     @property
     def events(self):
         """Returns how many events exist."""
         c = 0
-        for state in six.iterkeys(self._states):
+        for state in self._states:
             c += len(self._transitions[state])
         return c
 
     def __iter__(self):
         """Iterates over (start, event, end) transition tuples."""
-        for state in six.iterkeys(self._states):
+        for state in self._states:
             for event, target in self._transitions[state].items():
                 yield (state, event, target.name)
 
@@ -515,7 +514,7 @@ class HierarchicalFiniteMachine(FiniteMachine):
         """
         super(HierarchicalFiniteMachine, self).initialize(
             start_state=start_state)
-        for data in six.itervalues(self._states):
+        for data in self._states.values():
             if 'machine' in data:
                 nested_machine = data['machine']
                 nested_start_state = None

automaton/runners.py

@@ -14,8 +14,6 @@
 
 import abc
 
-import six
-
 from automaton import exceptions as excp
 from automaton import machines
 
@@ -26,8 +24,7 @@ _JUMPER_NOT_FOUND_TPL = ("Unable to progress since no reaction (or"
                          " in response to event '%s')")
 
 
-@six.add_metaclass(abc.ABCMeta)
-class Runner(object):
+class Runner(metaclass=abc.ABCMeta):
     """Machine runner used to run a state machine.
 
     Only **one** runner per machine should be active at the same time (aka

automaton/tests/test_fsm.py

@@ -20,7 +20,6 @@ from automaton import exceptions as excp
 from automaton import machines
 from automaton import runners
 
-import six
 from testtools import testcase
 
 
@@ -262,13 +261,13 @@ class FSMTest(testcase.TestCase):
         self.assertFalse(self.jumper.terminated)
         self.assertEqual([('down', 'up'), ('up', 'down'), ('down', 'up')],
                          up_downs)
-        self.assertRaises(StopIteration, six.next, it)
+        self.assertRaises(StopIteration, next, it)
 
     def test_run_send_fail(self):
         up_downs = []
         runner = runners.FiniteRunner(self.jumper)
         it = runner.run_iter('jump')
-        up_downs.append(six.next(it))
+        up_downs.append(next(it))
         self.assertRaises(excp.NotFound, it.send, 'fail')
         it.close()
         self.assertEqual([('down', 'up')], up_downs)
@@ -364,7 +363,7 @@ class HFSMTest(FSMTest):
 
         def phone_reaction(old_state, new_state, event, chat_iter):
             try:
-                six.next(chat_iter)
+                next(chat_iter)
             except StopIteration:
                 return 'finish'
             else:

lower-constraints.txt

@@ -1,4 +1,5 @@
 appdirs==1.3.0
+argparse==0.9.0
 cliff==3.1.0
 cmd2==0.8.9
 coverage==4.0
@@ -17,7 +18,6 @@ pyparsing==2.4.7
 pyperclip==1.8.0
 python-mimeparse==1.6.0
 python-subunit==1.0.0
-PyYAML==3.12
 reno==3.1.0
 requests==2.14.2
 requestsexceptions==1.2.0
@@ -26,7 +26,9 @@ stestr==2.0.0
 stevedore==1.20.0
 testrepository==0.0.20
 testtools==2.2.0
+toml==0.9.3
 traceback2==1.4.0
 unittest2==1.1.0
+virtualenv==20.0.8
 voluptuous==0.11.7
 wcwidth==0.2.4

requirements.txt

@@ -5,8 +5,5 @@
 # See: https://bugs.launchpad.net/pbr/+bug/1384919 for why this is here...
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
 
-# Python 2->3 compatibility library.
-six>=1.10.0 # MIT
-
 # For pretty formatting machines/state tables...
 PrettyTable<0.8,>=0.7.2 # BSD

test-requirements.txt

@@ -2,12 +2,9 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-hacking>=3.0,<3.1.0 # Apache-2.0
-
 coverage!=4.4,>=4.0 # Apache-2.0
 oslotest>=3.2.0 # Apache-2.0
 stestr>=2.0.0 # Apache-2.0
 testtools>=2.2.0 # MIT
 reno>=3.1.0 # Apache-2.0
 
-pre-commit>=2.6.0 # MIT

tox.ini

@@ -12,6 +12,8 @@ deps =
 commands = stestr run --slowest {posargs}
 
 [testenv:pep8]
+deps =
+    pre-commit>=2.6.0 # MIT
 commands = pre-commit run -a
 
 [testenv:venv]