object tags

kiln-core/src/tests/map_file/round_trip.rs

@@ -51,6 +51,83 @@ bg = "#000000"
     assert_eq!(obj2.glyph.bg, obj.glyph.bg);
 }
 
+#[test]
+fn object_tags_round_trip_through_toml() {
+    // Tags declared in the map file must survive a save→load cycle, sorted.
+    let toml = r##"
+[map]
+name = "Test"
+width = 3
+height = 3
+player_start = [0, 0]
+
+[palette]
+"." = { archetype = "empty", tile = 46, fg = "#000000", bg = "#000000" }
+
+[grid]
+content = """
+...
+...
+...
+"""
+
+[[objects]]
+x = 1
+y = 1
+tile = 64
+fg = "#ffffff"
+bg = "#000000"
+tags = ["enemy", "boss"]
+"##;
+    let mf: MapFile = toml::from_str(toml).unwrap();
+    let board = Board::try_from(mf).unwrap();
+    let obj = &board.objects[&1];
+    assert!(obj.tags.contains("enemy"));
+    assert!(obj.tags.contains("boss"));
+    assert_eq!(obj.tags.len(), 2);
+
+    // Save and reload; tags must survive, and be sorted alphabetically.
+    let toml_out = toml::to_string_pretty(&MapFile::from(&board)).unwrap();
+    // Both tags must appear; "boss" must come before "enemy" (sorted).
+    let boss_pos = toml_out.find("\"boss\"").expect("boss in TOML");
+    let enemy_pos = toml_out.find("\"enemy\"").expect("enemy in TOML");
+    assert!(boss_pos < enemy_pos, "tags must be sorted: boss before enemy");
+    let mf2: MapFile = toml::from_str(&toml_out).unwrap();
+    let board2 = Board::try_from(mf2).unwrap();
+    let obj2 = &board2.objects[&1];
+    assert_eq!(obj2.tags, obj.tags);
+}
+
+#[test]
+fn object_empty_tags_omitted_from_toml() {
+    // An object with no tags must not emit a `tags` key in TOML.
+    let toml = r##"
+[map]
+name = "Test"
+width = 1
+height = 1
+player_start = [0, 0]
+
+[palette]
+"." = { archetype = "empty", tile = 46, fg = "#000000", bg = "#000000" }
+
+[grid]
+content = """
+.
+"""
+
+[[objects]]
+x = 0
+y = 0
+tile = 64
+fg = "#ffffff"
+bg = "#000000"
+"##;
+    let board = load_board(toml);
+    let toml_out = toml::to_string_pretty(&MapFile::from(&board)).unwrap();
+    assert!(!toml_out.contains("tags"), "empty tags must not appear in TOML output");
+}
+
 #[test]
 fn floor_spec_round_trips_through_toml() {
     // A 2×2 board with a grid floor (a generator and a fixed glyph) must survive