Migrated % string formating

tests/docs/test_docs.py

@@ -14,9 +14,9 @@ class Doc_Test(unittest.TestCase):
         html_path = os.path.sep.join(self.path_to_docs.split(os.path.sep) + ['_build']+['html'])
 
         check = subprocess.call(["sphinx-build", "-nW", "-b", "html", "-d",
-            "%s"%(doctrees_path) ,
-            "%s"%(self.path_to_docs),
-            "%s"%(html_path)])
+            "{0!s}".format((doctrees_path)) ,
+            "{0!s}".format((self.path_to_docs)),
+            "{0!s}".format((html_path))])
         assert check == 0
 
     # def test_latex(self):