Switch to stestr

According to Openstack summit session [1],
stestr is maintained project to which all Openstack projects should migrate.
Let's switch to stestr as other projects have already moved to it.

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

Change-Id: Iebd624bd0ec71a1bdadf62b7e93853bfb3bfff73

.gitignore

@@ -26,8 +26,7 @@ cover/
 .coverage*
 !.coveragerc
 .tox
-nosetests.xml
-.testrepository
+.stestr/
 .venv
 
 # Translations
@@ -55,4 +54,4 @@ ChangeLog
 .*sw?
 
 # Files created by releasenotes build
-releasenotes/build
+releasenotes/build

.stestr.conf

@@ -0,0 +1,3 @@
+[DEFAULT]
+test_path=${OS_TEST_PATH:-./}
+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

@@ -8,3 +8,4 @@ sphinx>=1.6.2 # BSD
 openstackdocstheme>=1.11.0  # Apache-2.0
 # releasenotes
 reno>=1.8.0 # Apache-2.0
+stestr>=2.0.0 # Apache-2.0

tox.ini

@@ -12,7 +12,7 @@ setenv =
    VIRTUAL_ENV={envdir}
    PYTHONWARNINGS=default::DeprecationWarning
 deps = -r{toxinidir}/test-requirements.txt
-commands = python setup.py test --slowest --testr-args='{posargs}'
+commands = stest run --slowest {posargs}
 
 [testenv:pep8]
 commands = flake8 {posargs}