Test docs with tox.

tox.ini

@@ -24,6 +24,16 @@ deps =
 commands =
     pytest --flake8 --cov=oidc_provider {posargs}
 
+[testenv:docs]
+basepython = python2.7
+changedir = docs
+deps =
+    sphinx
+    sphinx_rtd_theme
+commands =
+    mkdir -p _static/
+    sphinx-build -v -W -b html -d {envtmpdir}/doctrees -D html_static_path="_static" . {envtmpdir}/html
+
 [pytest]
 DJANGO_SETTINGS_MODULE = oidc_provider.tests.settings
 python_files = test_*.py