Switch to use stestr for unit test

According to Openstack summit session [1],
stestr is maintained project to which all Openstack projects should migrate.
So we should switch to stestr.

[1] https://etherpad.openstack.org/p/YVR-python-pti

Change-Id: I33e075b3b7f2eec889cd1698edaab5ee89f69121

.gitignore

@@ -27,7 +27,7 @@ cover/
 !.coveragerc
 .tox
 nosetests.xml
-.testrepository
+.stestr/
 .venv
 
 # Translations

.stestr.conf

@@ -0,0 +1,3 @@
+[DEFAULT]
+test_path=./release_test/tests
+top_dir=.

.testr.conf

@@ -1,7 +0,0 @@
-[DEFAULT]
-test_command=OS_STDOUT_CAPTURE=${OS_STDOUT_CAPTURE:-1} \
-             OS_STDERR_CAPTURE=${OS_STDERR_CAPTURE:-1} \
-             OS_TEST_TIMEOUT=${OS_TEST_TIMEOUT:-60} \
-             ${PYTHON:-python} -m subunit.run discover -t ./ . $LISTOPT $IDOPTION
-test_id_option=--load-list $IDFILE
-test_list_option=--list

test-requirements.txt

@@ -9,7 +9,7 @@ python-subunit>=0.0.18
 sphinx!=1.2.0,!=1.3b1,<1.3,>=1.1.2
 oslosphinx>=2.5.0 # Apache-2.0
 oslotest>=1.10.0 # Apache-2.0
-testrepository>=0.0.18
+stestr>=2.0.0 # Apache-2.0
 testscenarios>=0.4
 testtools>=1.4.0
 reno>=0.1.1 # Apache2

tox.ini

@@ -11,7 +11,7 @@ deps =
   -r{toxinidir}/test-requirements.txt
   -r{toxinidir}/requirements.txt
 commands =
-  python setup.py test --coverage --coverage-package-name=oslo_config --slowest --testr-args='{posargs}'
+  python setup.py test --coverage --coverage-package-name=oslo_config --slowest {posargs}
   coverage report --show-missing
 
 [testenv:py27]
@@ -27,7 +27,14 @@ commands = {posargs}
 
 [testenv:cover]
 basepython = python3
-commands = python setup.py test --coverage --testr-args='{posargs}'
+setenv =
+   {[testenv]setenv}
+   PYTHON=coverage run --source release_test --parallel-mode
+commands =
+   stestr run {posargs}
+   coverage combine
+   coverage html -d cover
+   coverage xml -o cover/coverage.xml
 
 [testenv:docs]
 basepython = python3