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: Ia069985b92af920970af9e84d37e27ddc8625437
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

tox.ini

@@ -45,18 +45,21 @@ commands =
   coverage report
 
 [testenv:debug]
+basepython = python3
 description = Allows to run unit-test with debug mode enabled
 commands =
   {[testenv]commands}
   oslo_debug_helper -t {toxinidir}/monasca_log_api/tests {posargs}
 
 [testenv:bashate]
+basepython = python3
 description = Validates (pep8-like) devstack plugins
 skip_install = True
 usedevelop = False
 commands = bash {toxinidir}/tools/bashate.sh {toxinidir}/devstack
 
 [testenv:bandit]
+basepython = python3
 description = Validates codebase with bandit
 skip_install = True
 usedevelop = False
@@ -65,6 +68,7 @@ commands =
   bandit -r monasca_log_api -n5 -s B101 -x monasca_log_api/tests
 
 [testenv:pep8]
+basepython = python3
 description = Runs set of linters against codebase (flake8, bandit, bashate, checkniceness)
 commands =
   {[testenv]commands}
@@ -74,16 +78,19 @@ commands =
   {[testenv:checkniceness]commands}
 
 [testenv:flake8]
+basepython = python3
 description = Validates codebase with flake
 commands =
   {[testenv]commands}
   flake8 monasca_log_api
 
 [testenv:genconfig]
+basepython = python3
 description = Generates sample documentation file for monasca-log-api
 commands = oslo-config-generator --config-file=config-generator/monasca-log-api.conf
 
 [testenv:docs]
+basepython = python3
 description = Builds api-ref, api-guide, releasenotes and devdocs
 commands =
   {[testenv]commands}
@@ -93,6 +100,7 @@ commands =
   {[testenv:releasenotes]commands}
 
 [testenv:api-guide]
+basepython = python3
 description = Called from CI scripts to test and publish the API Guide
 commands =
   {[testenv]commands}
@@ -101,6 +109,7 @@ commands =
   sphinx-build -W -b html -d api-guide/build/doctrees api-guide/source api-guide/build/html
 
 [testenv:api-ref]
+basepython = python3
 description = Called from CI scripts to test and publish the API Ref
 commands =
   {[testenv]commands}
@@ -109,12 +118,14 @@ commands =
   sphinx-build -W -b html -d api-ref/build/doctrees api-ref/source api-ref/build/html
 
 [testenv:releasenotes]
+basepython = python3
 description = Called from CI script to test and publish the Release Notes
 commands =
   rm -rf releasenotes/build
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:devdocs]
+basepython = python3
 description = Builds developer documentation
 commands =
   {[testenv]commands}
@@ -124,6 +135,7 @@ commands =
   python setup.py build_sphinx
 
 [testenv:checkniceness]
+basepython = python3
 description = Validates (pep-like) documenation
 skip_install = True
 usedevelop = False
@@ -135,6 +147,7 @@ commands =
   doc8 --file-encoding utf-8 {toxinidir}/releasenotes
 
 [testenv:checkjson]
+basepython = python3
 description = Validates all json samples inside doc folder
 skip_install = True
 usedevelop = False
@@ -150,6 +163,7 @@ commands =
   bash -c '! find doc/ -type f -name *.json | xargs -t -n1 python -m json.tool 2>&1 > /dev/null | grep -B1 -v ^python'
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [flake8]