Drop ostestr in favor of stestr

With this patch we drop ostestr to use stestr directly to avoid
current and future incompatibilities that can break the test
process, e.g. [1]

Also some minor changes:
- following recent changes to global requirements [2],
we update sphinx requirements locally
- removing py35 in favor of generic py3 test
- updating upper-constraints link to use opendev.org

[1] https://bugs.launchpad.net/os-testr/+bug/1827834
[2] If558f184c959e4b63b56dec3ca1571d1034cfe5c

Change-Id: I9328fa7e68e1e03a20182e728840075bea7c5ac6

test-requirements.txt

@@ -8,7 +8,8 @@ flake8-import-order==0.11 # LGPLv3
 coverage!=4.4,>=4.0 # Apache-2.0
 doc8>=0.6.0 # Apache-2.0
 python-subunit>=1.0.0 # Apache-2.0/BSD
-sphinx!=1.6.6,!=1.6.7,>=1.6.2 # BSD
+sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7' # BSD
+sphinx!=1.6.6,!=1.6.7,>=1.6.2;python_version>='3.4' # BSD
 oslotest>=3.2.0 # Apache-2.0
 testscenarios>=0.4 # Apache-2.0/BSD
 testtools>=2.2.0 # MIT

tox.ini

@@ -1,20 +1,22 @@
 [tox]
 minversion = 1.8
 skipsdist = True
-envlist = py35,py27,pep8
+envlist = py3,py27,pep8
 
 [testenv]
 usedevelop = True
-install_command = pip install -U -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
+install_command = pip install -U {opts} {packages}
 setenv = VIRTUAL_ENV={envdir}
          PYTHONDONTWRITEBYTECODE = 1
          LANGUAGE=en_US
          LC_ALL=en_US.UTF-8
          TESTS_DIR=./ironic_staging_drivers/tests/unit/
 deps =
+    -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
     -r{toxinidir}/test-requirements.txt
     -r{toxinidir}/extra-requirements.txt
-commands = ostestr {posargs}
+commands =
+    stestr run {posargs}
 passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 
 [testenv:pep8]
@@ -29,11 +31,13 @@ commands = {posargs}
 
 [testenv:cover]
 basepython = python3
-setenv = {[testenv]setenv}
-         PYTHON=coverage run --source ironic_staging_drivers --omit='*tests*' --parallel-mode
+setenv =
+    VIRTUAL_ENV={envdir}
+    LANGUAGE=en_US
+    PYTHON=coverage run --source ironic_staging_drivers --omit='*tests*' --parallel-mode
 commands =
     coverage erase
-    ostestr {posargs}
+    stestr run {posargs}
     coverage combine
     coverage report --omit='*tests*'
     coverage html -d ./cover --omit='*tests*'