fix tox python3 overrides

We want to default to running all tox environments under python 3, so
set the basepython value in each environment.

We do not want to specify a minor version number, because we do not
want to have to update the file every time we upgrade python.

We do not want to set the override once in testenv, because that
breaks the more specific versions used in default environments like
py35 and py36.

Change-Id: I9df9ee69b590e2589b7e687a7062bbfb19b6efbd
Signed-off-by: Doug Hellmann <doug@doughellmann.com>
Co-Authored-By: Nguyen Hai <nguyentrihai93@gmail.com>
Co-Authored-By: Trinh Nguyen <dangtrinhnt@gmail.com>

freezer/engine/engine.py

@@ -16,7 +16,6 @@
 import abc
 import json
 import multiprocessing
-from multiprocessing import queues
 import shutil
 import tempfile
 import time
@@ -31,6 +30,12 @@ from freezer.storage import base
 from freezer.utils import streaming
 from freezer.utils import utils
 
+if six.PY3:
+    from multiprocessing import SimpleQueue
+else:
+    from multiprocessing.queues import SimpleQueue
+
+
 LOG = log.getLogger(__name__)
 
 
@@ -249,10 +254,7 @@ class BackupEngine(object):
         max_level = max(backups.keys())
 
         # Use SimpleQueue because Queue does not work on Mac OS X.
-        if six.PY2:
-            read_except_queue = queues.SimpleQueue()
-        else:
-            read_except_queue = multiprocessing.SimpleQueue()
+        read_except_queue = SimpleQueue()
         LOG.info("Restoring backup {0}".format(hostname_backup_name))
         for level in range(0, max_level + 1):
             LOG.info("Restoring from level {0}".format(level))
@@ -269,10 +271,7 @@ class BackupEngine(object):
             # Start the tar pipe consumer process
 
             # Use SimpleQueue because Queue does not work on Mac OS X.
-            if six.PY2:
-                write_except_queue = queues.SimpleQueue()
-            else:
-                write_except_queue = multiprocessing.SimpleQueue()
+            write_except_queue = SimpleQueue()
 
             engine_stream = multiprocessing.Process(
                 target=self.restore_level,

tox.ini

@@ -45,6 +45,7 @@ python_files = test_*.py
 norecursedirs  = .tox .venv
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:py27]
@@ -57,6 +58,7 @@ basepython = python3.5
 basepython = python3.6
 
 [testenv:docs]
+basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 whitelist_externals = rm
 commands =
@@ -65,11 +67,13 @@ commands =
 
 
 [testenv:pep8]
+basepython = python3
 commands =
     flake8 freezer
     doc8 {posargs}
 
 [testenv:pylint]
+basepython = python3
 commands = pylint --rcfile .pylintrc freezer
 
 [flake8]
@@ -83,6 +87,7 @@ ignore = D000,D001
 ignore-path = .venv,.git,.tox,.tmp,*freezer/locale*,*lib/python*,freezer.egg*,doc/build,releasenotes/*,doc/source/contributor/api
 
 [testenv:releasenotes]
+basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 whitelist_externals = rm
 commands =