test_taxonomy: add test cases for taxonomy_base="empty"

Signed-off-by: Mark McLoughlin <markmc@redhat.com>

Author: markmc

tests/test_taxonomy.py

@@ -62,6 +62,13 @@ def _init_taxonomy(self, taxonomy_dir):
                 True,
                 ["compositional_skills->new", "compositional_skills->tracked"],
             ),
+            ("empty", True, False, ["compositional_skills->tracked"]),
+            (
+                "empty",
+                True,
+                True,
+                ["compositional_skills->new", "compositional_skills->tracked"],
+            ),
         ],
     )
     def test_read_taxonomy_leaf_nodes(