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: I04b87b308a82113a57ea41bde0329e92b07b642e

cinderclient/utils.py

@@ -187,7 +187,7 @@ def print_list(objs, fields, exclude_unavailable=False, formatters=None,
 
 def _encode(src):
     """remove extra 'u' in PY2."""
-    if six.PY2 and isinstance(src, unicode):
+    if six.PY2 and isinstance(src, six.text_type):
         return src.encode('utf-8')
     return src
 

tox.ini

@@ -24,9 +24,11 @@ commands = find . -type f -name "*.pyc" -delete
 whitelist_externals = find
 
 [testenv:pep8]
+basepython = python3
 commands = flake8
 
 [testenv:pylint]
+basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
   -r{toxinidir}/requirements.txt
@@ -35,9 +37,11 @@ commands = bash tools/lintstack.sh
 whitelist_externals = bash
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [testenv:cover]
+basepython = python3
 setenv =
     {[testenv]setenv}
     PYTHON=coverage run --source cinderclient --parallel-mode
@@ -48,6 +52,7 @@ commands =
     coverage xml -o cover/coverage.xml
 
 [testenv:docs]
+basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
   -r{toxinidir}/requirements.txt
@@ -55,6 +60,7 @@ deps =
 commands = sphinx-build -b html doc/source doc/build/html
 
 [testenv:releasenotes]
+basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
   -r{toxinidir}/requirements.txt
@@ -62,6 +68,7 @@ deps =
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:functional]
+basepython = python3
 commands = ostestr {posargs}
 setenv =
   {[testenv]setenv}