Use a testing matrix and run the tests with tox

Author: PCManticore

.travis.yml

@@ -1,11 +1,13 @@
 language: python
-python:
-  - "2.6"
-  - "2.7"
-  - "3.6"
-  - "pypy"
+matrix:
+  include:
+    - python: 2.6
+      env: TOXENV=py26
+    - python: 3.6
+      env: TOXENV=py36
+    - python: pypy
+      env: TOXENV=pypy
 install:
-  - python setup.py install
-  - pip install -r test_requirements.txt
+  - pip install tox
 script:
-  - python setup.py test
+  - tox -e $TOXENV

tox.ini

@@ -0,0 +1,8 @@
+[tox]
+envlist = py27,py36,pypy
+skip_missing_interpreters = true
+
+[testenv]
+deps = -rtest_requirements.txt
+
+commands = python setup.py test