Migrate from testr to stestr

* Replace .testr.conf by .stestr.conf for migration and update
  .gitignore, tox.ini and test-requirements.txt files accordingly
* Use py3 as the default runtime for tox

Signed-off-by: HeroicHitesh <email.hiteshkumar@gmail.com>
Change-Id: I0948bd22e257285c77fb61564684ab31080ecf54

.gitignore

@@ -1,16 +1,25 @@
-*.swp
+*.log
+subunit.log
+.autogenerated
+*.py[co]
+
+# Packages
 dist/
-.tox
 *.egg
 *.egg-info
-*.py[co]
 .DS_Store
-*.log
-.testrepository
-subunit.log
 build
-.autogenerated
+
+# Unit test
 .coverage
 cover/
 coverage.xml
+.stestr
+.tox
+.venv
+
+# Sphinx
 doc/source/api/
+
+# Editors
+*.swp

.stestr.conf

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

.testr.conf

@@ -1,4 +0,0 @@
-[DEFAULT]
-test_command=${PYTHON:-python} -m subunit.run discover -t ./ ./tests $LISTOPT $IDOPTION
-test_id_option=--load-list $IDFILE
-test_list_option=--list

test-requirements.txt

@@ -2,5 +2,5 @@ hacking>=0.10.0,<0.11
 
 coverage>=3.6
 mock>=1.0
-testrepository>=0.0.17
+stestr>=2.0.0 # Apache-2.0
 testtools>=0.9.32

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py37,py27,pypy,pep8
+envlist = py3,pypy,pep8
 minversion = 1.6
 
 [testenv]
@@ -7,7 +7,7 @@ setenv = VIRTUAL_ENV={envdir}
 
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
-commands = python setup.py testr --testr-args="{posargs}"
+commands = stestr run --slowest {posargs}
 passenv = *_proxy *_PROXY
 
 [testenv:pep8]