Unit test for failing TapTree on builder containing hidden nodes.

Author: dr-orlovsky

src/util/psbt/serialize.rs

@@ -388,6 +388,14 @@ mod tests {
         builder
     }
 
+    #[test]
+    fn taptree_hidden() {
+        let mut builder = compose_taproot_builder(0x51, &[2, 2, 2]);
+        builder = builder.add_leaf_with_ver(3, Script::from_hex("b9").unwrap(), LeafVersion::from_consensus(0xC2).unwrap()).unwrap();
+        builder = builder.add_hidden_node(3, sha256::Hash::default()).unwrap();
+        assert!(TapTree::from_inner(builder.clone()).is_err());
+    }
+
     #[test]
     fn taptree_roundtrip() {
         let mut builder = compose_taproot_builder(0x51, &[2, 2, 2, 3]);