Switch from tox to nox

Recent tox releases have put us on a config treadmill. Avoid these
issues entirely by using nox. Nox is a tox alternative that uses
standard tools like pip and should be simpler to use for us.

Change-Id: I24277512cf542bac7a8852d50009c6f08db7fa37

.gitignore

@@ -3,6 +3,7 @@
 .eggs/*
 
 .tox
+.nox
 .stestr
 build/*
 *.pyc

.zuul.yaml

@@ -13,18 +13,18 @@
     check:
       jobs:
         - gerritlib-jeepyb-integration
-        - tox-py38:
+        - nox-py38:
             nodeset: ubuntu-focal
-        - tox-py39:
+        - nox-py39:
             nodeset: ubuntu-focal
-        - tox-py310:
+        - nox-py310:
             nodeset: ubuntu-jammy
     gate:
       jobs:
         - gerritlib-jeepyb-integration
-        - tox-py38:
+        - nox-py38:
             nodeset: ubuntu-focal
-        - tox-py39:
+        - nox-py39:
             nodeset: ubuntu-focal
-        - tox-py310:
+        - nox-py310:
             nodeset: ubuntu-jammy

README.rst

@@ -42,7 +42,7 @@ Writing a patch
 ---------------
 
 We ask that all code submissions be pep8_ and pyflakes_ clean.  The
-easiest way to do that is to run tox_ before submitting code for
+easiest way to do that is to run nox_ before submitting code for
 review in Gerrit.  It will run ``pep8`` and ``pyflakes`` in the same
 manner as the automated test suite that will run on proposed
 patchsets.
@@ -57,6 +57,6 @@ Then install the required python packages using pip_::
 
 .. _Gerrit: https://www.gerritcodereview.com/
 .. _pyflakes: https://pypi.python.org/pypi/pyflakes
-.. _tox: https://testrun.org/tox
+.. _nox: https://nox.thea.codes/en/stable/
 .. _pip: https://pypi.python.org/pypi/pip
 .. _pep8: https://pypi.python.org/pypi/pep8

doc/source/installation.rst

@@ -33,7 +33,7 @@ Documentation
 Documentation is included in the ``doc`` folder. To generate docs
 locally execute the command::
 
-    tox -e docs
+    nox -s docs
 
 The generated documentation is then available under
 ``doc/build/html/index.html``.
@@ -44,7 +44,7 @@ Unit Tests
 Unit tests are in the ``tests`` folder.
 To run the unit tests, execute the command::
 
-    tox -e py27
+    nox -s tests
 
-* Note: View ``tox.ini`` to run tests on other versions of Python.
+* Note: Pass ``--force-python 3.x`` to run under other versions of python.
 

noxfile.py

@@ -0,0 +1,46 @@
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License.  You may obtain
+# a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import nox
+
+
+nox.options.error_on_external_run = True
+nox.options.reuse_existing_virtualenvs = True
+nox.options.sessions = ["tests-3", "linters"]
+
+
+@nox.session(python="3")
+def linters(session):
+    session.install("hacking")
+    session.install("-e", ".")
+    session.run("flake8")
+
+
+@nox.session(python="3")
+def docs(session):
+    session.install("-r", "test-requirements.txt")
+    session.install("-e", ".")
+    session.run("python3", "setup.py", "build_sphinx")
+
+
+@nox.session(python="3")
+def venv(session):
+    session.install("-r", "test-requirements.txt")
+    session.install("-e", ".")
+    session.run(*session.posargs)
+
+
+@nox.session(python="3")
+def tests(session):
+    session.install("-r", "test-requirements.txt")
+    session.install("-e", ".")
+    session.run("stestr", "run", "--slowest", *session.posargs)

setup.cfg

@@ -32,3 +32,12 @@ warnerrors = True
 source-dir = doc/source
 build-dir = doc/build
 all_files = 1
+
+[flake8]
+show-source = True
+# These are ignored intentionally in infra projects;
+# please don't submit patches that solely correct them or enable them.
+ignore =
+    E124,E125,E129,E252,E402,E741,H,W503,W504
+    N802  # N802 function name {} should be lowercase
+exclude = .venv,.tox,.nox,dist,doc,build,*.egg

tox.ini

@@ -1,31 +0,0 @@
-[tox]
-minversion = 1.6
-skip_missing_interpreters = false
-# https://docs.python.org/devguide/#status-of-python-branches
-envlist = pep8, py{310,39,38,py}
-
-[testenv]
-setenv = VIRTUAL_ENV={envdir}
-deps = -r{toxinidir}/test-requirements.txt
-commands =
-    stestr run --slowest {posargs}
-
-[testenv:pep8]
-deps =
-    hacking
-commands = flake8
-
-[testenv:docs]
-commands = python setup.py build_sphinx
-
-[testenv:venv]
-commands = {posargs}
-
-[flake8]
-show-source = True
-# These are ignored intentionally in infra projects;
-# please don't submit patches that solely correct them or enable them.
-ignore =
-    E124,E125,E129,E252,E402,E741,H,W503,W504
-    N802  # N802 function name {} should be lowercase
-exclude = .venv,.tox,dist,doc,build,*.egg