use the default "contents.rst" as the index document

Author: jbweston

tests/test_execute.py

@@ -33,15 +33,15 @@ def doctree(source, config=None, return_warnings=False):
             f.write("extensions = ['jupyter_sphinx.execute']")
             if config is not None:
                 f.write('\n' + config)
-        with open(os.path.join(src_dir, 'index.rst'), 'w') as f:
+        with open(os.path.join(src_dir, 'contents.rst'), 'w') as f:
             f.write(source)
         warnings = StringIO()
         app = SphinxTestApp(srcdir=path(src_dir), status=StringIO(),
                             warning=warnings)
         apps.append(app)
         app.build()
 
-        doctree = app.env.get_doctree("index")
+        doctree = app.env.get_doctree("contents")
 
         if return_warnings:
             return doctree, warnings.getvalue()