tox: Add environment documentation

This should be helpful for new contributors.

Change-Id: I91c14bbaeb61bdf7026015a3eb3f21edae8ec2a9
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

tox.ini

@@ -3,7 +3,8 @@ minversion = 4.3.0
 envlist = pep8,py3
 
 [testenv]
-usedevelop = true
+description =
+    Run unit tests.
 passenv =
     OS_*
     OPENSTACKSDK_*
@@ -23,6 +24,8 @@ commands =
     stestr slowest
 
 [testenv:functional{,-py36,-py37,-py38,-py39}]
+description =
+    Run functional tests.
 # Some jobs (especially heat) takes longer, therefore increase default timeout
 # This timeout should not be smaller, than the longest individual timeout
 setenv =
@@ -37,6 +40,8 @@ commands =
 
 # Acceptance tests are the ones running on real clouds
 [testenv:acceptance-regular-user]
+description =
+    Run acceptance tests.
 # This env intends to test functions of a regular user without admin privileges
 # Some jobs (especially heat) takes longer, therefore increase default timeout
 # This timeout should not be smaller, than the longest individual timeout
@@ -53,12 +58,16 @@ commands =
     stestr slowest
 
 [testenv:pep8]
+description =
+    Run style checks.
 deps =
     pre-commit
 commands =
     pre-commit run --all-files --show-diff-on-failure
 
 [testenv:venv]
+description =
+    Run specified command in a virtual environment with all dependencies installed.
 deps =
     -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
     -r{toxinidir}/test-requirements.txt
@@ -67,6 +76,8 @@ deps =
 commands = {posargs}
 
 [testenv:debug]
+description =
+    Run specified tests through oslo_debug_helper, which allows use of pdb.
 # allow 1 year, or 31536000 seconds, to debug a test before it times out
 setenv =
     OS_TEST_TIMEOUT=31536000
@@ -76,6 +87,8 @@ commands =
     oslo_debug_helper -t openstack/tests {posargs}
 
 [testenv:cover]
+description =
+    Run unit tests and generate coverage report.
 setenv =
     {[testenv]setenv}
     PYTHON=coverage run --source openstack --parallel-mode
@@ -86,6 +99,8 @@ commands =
     coverage xml -o cover/coverage.xml
 
 [testenv:ansible]
+description =
+    Run ansible tests.
 # Need to pass some env vars for the Ansible playbooks
 passenv =
     HOME
@@ -97,6 +112,8 @@ deps =
 commands = {toxinidir}/extras/run-ansible-tests.sh -e {envdir} {posargs}
 
 [testenv:docs]
+description =
+    Build documentation in HTML format.
 deps =
     -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
     -r{toxinidir}/doc/requirements.txt
@@ -104,6 +121,8 @@ commands =
     sphinx-build -W --keep-going -b html -j auto doc/source/ doc/build/html
 
 [testenv:pdf-docs]
+description =
+    Build documentation in PDF format.
 deps = {[testenv:docs]deps}
 allowlist_externals =
     make
@@ -112,6 +131,8 @@ commands =
     make -C doc/build/pdf
 
 [testenv:releasenotes]
+description =
+    Build release note documentation in HTML format.
 deps =
     -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
     -r{toxinidir}/doc/requirements.txt