Move linters dependencies to tox.ini

One of suggestions discussed in the mailling thread [1] is to decouple
linters from test-requirements.txt. We uses specific versions of linters
(hacking, flake8, pylint and bandit) and they are potentially incompatbile
with other libraries in test-requirements.txt.
One example is bandit incompatibility detected by the new pip resolver.
This commit moves linters to tox.ini and introduces a new tox envdir
shared by linter related tox envs.

Note that we have a unit test for a local hacking rule so hacking needs
to be installed as part of the default dependencies. We can have it in
test-requirements.txt but I think it is better to have it in tox.ini
as hacking is a part of linters and other linter dependencies are
declared in tox.ini now.

[1] http://lists.openstack.org/pipermail/openstack-discuss/2020-December/thread.html#19362

Change-Id: Ia41c5f665f01bdab187c9256b2319885998d12c3

lower-constraints.txt

@@ -3,7 +3,6 @@ amqp==2.1.1
 appdirs==1.4.0
 asn1crypto==0.23.0
 Babel==2.6.0
-bandit==1.4.0
 cachetools==2.0.0
 cffi==1.14.0
 chardet==3.0.4
@@ -78,7 +77,6 @@ positional==1.2.1
 prettytable==0.7.2
 pycodestyle==2.5.0
 pycparser==2.18
-pyflakes==2.1.0
 Pygments==2.2.0
 pyinotify==0.9.6
 pymongo==3.0.2

test-requirements.txt

@@ -6,19 +6,13 @@
 # added in alphabetical order, however, some dependencies may need to
 # be installed in a specific order.
 #
-# Hacking should appear first in case something else depends on pep8
-hacking>=3.0.1,<3.1.0 # Apache-2.0
-#
-bandit!=1.6.0,>=1.4.0 # Apache-2.0
 coverage!=4.4,>=4.0 # Apache-2.0
-flake8-import-order==0.12 # LGPLv3
 freezegun>=0.3.15 # Apache-2.0
 nodeenv>=0.9.4 # BSD
 pytest>=5.3.5 # MIT
 pytest-django>=3.8.0 # BSD (3 clause)
 pytest-html>=2.0.1 #MPL-2.0
 python-memcached>=1.59 # PSF
-pylint==2.6.0 # GPLv2
 selenium>=2.50.1 # Apache-2.0
 testscenarios>=0.4 # Apache-2.0/BSD
 testtools>=2.2.0 # MIT

tox.ini

@@ -23,6 +23,8 @@ deps =
   -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/test-requirements.txt
   -r{toxinidir}/requirements.txt
+  # Unit test for a local hacking rule requires hacking.
+  hacking>=3.0.1,<3.1.0 # Apache-2.0
 commands =
   find . -type f -name "*.pyc" -delete
   bash {toxinidir}/tools/unit_tests.sh {toxinidir} {posargs}
@@ -32,13 +34,20 @@ deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt
   -r{toxinidir}/requirements.txt
+  # Unit test for a local hacking rule requires hacking.
+  hacking>=3.0.1,<3.1.0 # Apache-2.0
 
 [testenv:venv]
 envdir = {toxworkdir}/venv
 commands = {posargs}
 
 [testenv:pep8]
-envdir = {toxworkdir}/venv
+envdir = {toxworkdir}/linters
+deps =
+  {[testenv]deps}
+  flake8-import-order==0.12 # LGPLv3
+  pylint==2.6.0 # GPLv2
+  bandit!=1.6.0,>=1.4.0 # Apache-2.0
 setenv =
   DJANGO_SETTINGS_MODULE=openstack_dashboard.test.settings
 commands =
@@ -131,7 +140,6 @@ commands =
   doc8 doc/source
 
 [testenv:pdf-docs]
-basepython = python3
 envdir = {toxworkdir}/docs
 deps = {[testenv:docs]deps}
 whitelist_externals =
@@ -164,12 +172,14 @@ commands =
     {envpython} {toxinidir}/manage.py compilemessages -v 0 --traceback
 
 [testenv:bandit]
-envdir = {toxworkdir}/venv
+envdir = {toxworkdir}/linters
+deps = {[testenv:pep8]deps}
 commands = bandit -r horizon openstack_auth openstack_dashboard -n5 -x tests -ll
 
 [testenv:bandit-baseline]
-envdir = {toxworkdir}/venv
-commands = bandit-baseline -r horizon  openstack_auth openstack_dashboard -n5 -x tests -ii -ll
+envdir = {toxworkdir}/linters
+deps = {[testenv:pep8]deps}
+commands = bandit-baseline -r horizon openstack_auth openstack_dashboard -n5 -x tests -ii -ll
 
 [flake8]
 filename = *.py,django.wsgi