[tox] update tox.ini to enable debugging

This change adds supprot for OS_DEBUG and also configures
default testing timeouts and log capture.

Change-Id: I685fee4081cdee82c508b6d25c534483f2caf09b

tox.ini

@@ -10,7 +10,11 @@ allowlist_externals = find
                       rm
 install_command = pip install -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master} {opts} {packages}
 setenv =
-   VIRTUAL_ENV={envdir}
+  VIRTUAL_ENV={envdir}
+  OS_STDOUT_CAPTURE=1
+  OS_STDERR_CAPTURE=1
+  OS_TEST_TIMEOUT=30
+  PYTHONDONTWRITEBYTECODE=1
 deps =
     -r{toxinidir}/test-requirements.txt
     -r{toxinidir}/requirements.txt
@@ -26,6 +30,12 @@ passenv =
   HTTPS_PROXY
   no_proxy
   NO_PROXY
+  OS_DEBUG
+  # NOTE(sean-k-mooney) optimization is enabled by default and when enabled
+  # asserts are complied out. Disable optimization to allow asserts in
+  # nova to fire in unit and functional tests. This can be useful for
+  # debugging issue with fixtures and mocks.
+  PYTHONOPTIMIZE
 
 [testenv:pep8]
 commands =