Add option_asset! to match asset! (#4791)

packages/manganis/manganis-macro/tests/option_asset.rs

@@ -0,0 +1,17 @@
+use manganis::{asset, option_asset, Asset};
+
+#[test]
+fn resolves_existing_asset() {
+    const REQUIRED: Asset = asset!("/assets/asset.txt");
+    const OPTIONAL: Option<Asset> = option_asset!("/assets/asset.txt");
+
+    let optional = OPTIONAL.expect("option_asset! should return Some for existing assets");
+    assert_eq!(optional.to_string(), REQUIRED.to_string());
+}
+
+#[test]
+fn missing_asset_returns_none() {
+    const OPTIONAL: Option<Asset> = option_asset!("/assets/does_not_exist.txt");
+
+    assert!(OPTIONAL.is_none());
+}