supplycommit: use provided asset ID in metadata lookup if set

If an asset ID is supplied, use it when fetching asset metadata in
FetchLatestAssetMetadata.

Author: ffranr

universe/supplycommit/env.go

@@ -268,6 +268,24 @@ func FetchLatestAssetMetadata(ctx context.Context, lookup AssetLookup,
 
 	var zero proof.MetaReveal
 
+	// If the asset specifier has an asset ID, then we'll use that to
+	// fetch the asset metadata.
+	if assetSpec.HasId() {
+		assetID, err := assetSpec.UnwrapIdOrErr()
+		if err != nil {
+			return zero, err
+		}
+
+		metaReveal, err := lookup.FetchAssetMetaForAsset(ctx, assetID)
+		if err != nil {
+			return zero, fmt.Errorf("faild to fetch asset meta: %w",
+				err)
+		}
+
+		return *metaReveal, nil
+	}
+
+	// Otherwise, we'll need to fetch the asset group using the group key.
 	groupKey, err := assetSpec.UnwrapGroupKeyOrErr()
 	if err != nil {
 		return zero, err

universe/supplycommit/state_machine_test.go

@@ -1339,11 +1339,16 @@ func TestSupplyCommitFinalizeStateTransitions(t *testing.T) {
 			},
 			assetSpec: assetIDSpec,
 		})
+
+		h.expectAssetLookup()
+		h.expectSupplySyncer()
+		h.expectApplyStateTransition()
+
 		h.start()
 		defer h.stopAndAssert()
 
-		expectedErr := errors.New("unable to fetch latest asset " +
-			"metadata: unable to unwrap asset group public key")
+		expectedErr := errors.New("group key must be specified for " +
+			"supply tree: unable to unwrap asset group public key")
 		h.expectFailure(expectedErr)
 
 		finalizeEvent := &FinalizeEvent{}