Clean up test runs and impove test coverage for sphinx

tests/test_sphinx.py

@@ -1,14 +1,37 @@
 # -*- coding: utf-8 -*-
 import subprocess
 import os
+from shutil import rmtree
 
 from django.test import TestCase
 from django.conf import settings
+from django.utils.six import StringIO
+from sphinx.application import Sphinx
 
 
 class SphinxTests(TestCase):
     docs_dir = os.path.join(settings.BASE_DIR, 'docs')
 
+    def tearDown(self):
+        build_dir = os.path.join(self.docs_dir, '_build')
+        if os.path.exists(build_dir):
+            rmtree(build_dir)
+
+    def test_extension(self):
+        stdout = StringIO()
+        s = Sphinx(
+            self.docs_dir,
+            self.docs_dir,
+            '%s/_build/html' % self.docs_dir,
+            '%s/_build/doctrees' % self.docs_dir,
+            'html',
+            status=stdout,
+        )
+        s.build()
+        output = stdout.getvalue()
+        stdout.close()
+        self.assertIn('build succeeded.', output)
+
     def test_multiprocessing(self):
         output = subprocess.check_output([
             'sphinx-build',