Support single test

Support to run single test, e.g.
tox -epy27 -- -n senlin.tests.unit.profiles.test_nova_server
Change-Id: I1bc36a624b7cfced3aba721bfeeb780c3b5e3214

.testr.conf

@@ -1,6 +1,6 @@
 [DEFAULT]
 test_command=
     PYTHON=$(echo ${PYTHON:-python} | sed 's/--source senlin//g')
-    ${PYTHON} -m subunit.run discover -s . $LISTOPT $IDOPTION
+    ${PYTHON} -m subunit.run discover ${OS_TEST_PATH:-./senlin/tests} -t . $LISTOPT $IDOPTION
 test_id_option=--load-list $IDFILE
 test_list_option=--list

tox.ini

@@ -9,6 +9,7 @@ skipsdist = True
 # random hash seed successfully.
 setenv = VIRTUAL_ENV={envdir}
          PYTHONHASHSEED=0
+         OS_TEST_PATH=senlin/tests/unit
 
 deps = -r{toxinidir}/test-requirements.txt
 
@@ -16,16 +17,19 @@ usedevelop = True
 install_command = pip install {opts} {packages}
 commands =
     find . -type f -name "*.pyc" -delete
-    ostestr --slowest --regex '^((?!tests\.functional).)+$' {posargs}
+    ostestr --slowest {posargs}
 
 whitelist_externals = bash
                       find
 
 [testenv:functional]
+setenv = VIRTUAL_ENV={envdir}
+         PYTHONHASHSEED=0
+         OS_TEST_PATH=senlin/tests/functional
 passenv = OS_USERNAME OS_PASSWORD OS_TENANT_NAME OS_USER_DOMAIN_NAME OS_PROJECT_DOMAIN_NAME OS_REGION_NAME OS_AUTH_URL
 commands =
     find . -type f -name "*.pyc" -delete
-    ostestr --slowest --concurrency 1 --regex '^(.*?tests\.functional)' {posargs}
+    ostestr --slowest --concurrency 1 {posargs}
 
 [testenv:pep8]
 commands =