Add another test for empty toctree

tests/roots/test-toctree-empty/_templates/localtoc.html

@@ -0,0 +1,2 @@
+{# This will call toctree unconditionally, whether there is a local or global toc #}
+{{ toctree() }}

tests/roots/test-toctree-empty/conf.py

@@ -3,3 +3,4 @@
 master_doc = 'index'
 html_theme = 'classic'
 exclude_patterns = ['_build']
+templates_path = ['_templates']

tests/test_toctree.py

@@ -30,7 +30,6 @@ def test_relations(app, status, warning):
 
 @pytest.mark.sphinx('singlehtml', testroot='toctree-empty')
 def test_singlehtml_toctree(app, status, warning):
-    docname = 'index'
     app.builder.build_all()
     try:
         app.builder._get_local_toctree('index')