tests: fix render test for ATT&CK metadata

tests/test_render.py

@@ -28,6 +28,9 @@ def test_render_meta_attack():
         rule:
           meta:
             name: test rule
+            scope: function
+            authors:
+              - foo
             att&ck:
               - {:s}
           features:
@@ -37,13 +40,13 @@ def test_render_meta_attack():
         )
     )
     r = capa.rules.Rule.from_yaml(rule)
-    rule_meta = capa.render.result_document.convert_meta_to_result_document(r.meta)
-    attack = rule_meta["att&ck"][0]
+    rule_meta = capa.render.result_document.RuleMetadata.from_capa(r)
+    attack = rule_meta.attack[0]
 
-    assert attack["id"] == id
-    assert attack["tactic"] == tactic
-    assert attack["technique"] == technique
-    assert attack["subtechnique"] == subtechnique
+    assert attack.id == id
+    assert attack.tactic == tactic
+    assert attack.technique == technique
+    assert attack.subtechnique == subtechnique
 
     assert capa.render.utils.format_parts_id(attack) == canonical