Fix run_tests to use pytest. (#1033)

Update tox.ini envlist.

run_tests

@@ -26,7 +26,7 @@ fi
 # For use on build server, we need exit code to be representative of success/failure
 if [ "$1" = '-x' ]; then
     shift 1
-    /usr/bin/env python -m unittest discover -v -s tests $@ 2>&1
+    /usr/bin/env python -m pytest -v tests $@ 2>&1
 else
-    /usr/bin/env python -m unittest discover -v -s tests $@ 2>&1 | egrep -v '^test_' | $safe_rg
+    /usr/bin/env python -m pytest -v tests $@ 2>&1 | egrep -v '^test_' | $safe_rg
 fi

tox.ini

@@ -1,22 +1,15 @@
 [tox]
-envlist=py26,py27,py33,py34,py35,py36,py37,pypy,flake8
+envlist=py27,py34,py35,py36,py37,pypy,flake8
 
 [testenv]
-commands=py.test --cov rq --durations=5 {posargs}
+commands=pytest --cov rq --durations=5 {posargs}
 deps=
     pytest
     pytest-cov
     mock
 
-[testenv:py26]
-deps=
-    pytest
-    pytest-cov
-    unittest2
-    mock
-
 [testenv:flake8]
-basepython = python2.7
+basepython = python3.6
 deps =
     flake8
 commands =