Replace testr to stestr

According to Openstack summit session [1] stestr is maintained
project to which all Openstack projects should migrate.
Let's switch it then.

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

Change-Id: I0d2391779623135551f095f8f4b61a2d523c6f35

.testr.conf

@@ -1,10 +0,0 @@
-[DEFAULT]
-test_command=OS_STDOUT_CAPTURE=${OS_STDOUT_CAPTURE:-1} \
-             OS_STDERR_CAPTURE=${OS_STDERR_CAPTURE:-1} \
-             OS_LOG_CAPTURE=${OS_LOG_CAPTURE:-1} \
-             OS_DEBUG=${OS_DEBUG:-1} \
-             OS_TEST_TIMEOUT=${OS_TEST_TIMEOUT:-160} \
-             ${PYTHON:-python} -m subunit.run discover -t ./ ${OS_TEST_PATH:-./designate/tests} $LISTOPT $IDOPTION
-
-test_id_option=--load-list $IDFILE
-test_list_option=--list

tox.ini

@@ -51,11 +51,17 @@ commands =
 
 [testenv:cover]
 basepython = python3
+setenv =
+    {[testenv]setenv}
+    PYTHON=coverage run --source designate --parallel-mode
 commands =
   coverage erase
   find . -type f -name "*.pyc" -delete
-  python setup.py testr --coverage --testr-args='{posargs}'
-  coverage report
+  stestr run --no-subunit-trace {posargs}
+  coverage combine
+  coverage report --skip-covered
+  coverage html -d cover
+  coverage xml -o cover/coverage.xml
 
 [testenv:bandit]
 basepython = python3