[rfw] Make widget builders work with loops (#8650)

**Make widget builders work with loops**

Fixes flutter/flutter#161544

Author: tugorez

packages/rfw/CHANGELOG.md

@@ -1,6 +1,7 @@
-## NEXT
+## 1.0.31
 
 * Updates minimum supported SDK version to Flutter 3.22/Dart 3.4.
+* Fixes an issue where Widget Builders didn't work properly with Loops.
 
 ## 1.0.30
 

packages/rfw/lib/src/flutter/runtime.dart

@@ -780,6 +780,10 @@ abstract class _CurriedWidget extends BlobNode {
             );
           } else if (inputList is DataReference) {
             inputList = dataResolver(inputList.parts);
+          } else if (inputList is WidgetBuilderArgReference) {
+            inputList = widgetBuilderArgResolver(
+              <Object>[inputList.argumentName, ...inputList.parts],
+            );
           } else if (inputList is BoundStateReference) {
             inputList = stateResolver(inputList.parts, inputList.depth);
           } else if (inputList is BoundLoopReference) {

packages/rfw/pubspec.yaml

@@ -2,7 +2,7 @@ name: rfw
 description: "Remote Flutter widgets: a library for rendering declarative widget description files at runtime."
 repository: https://github.com/flutter/packages/tree/main/packages/rfw
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+rfw%22
-version: 1.0.30
+version: 1.0.31
 
 environment:
   sdk: ^3.4.0

packages/rfw/test/runtime_test.dart

@@ -1606,6 +1606,54 @@ void main() {
     expect(textFinder, findsOneWidget);
     expect(tester.widget<Text>(textFinder).data, 'The input is true, the output is false');
   });
+
+  testWidgets('Widget builders - builder works with loops', (WidgetTester tester) async {
+    const LibraryName coreLibraryName = LibraryName(<String>['core']);
+    const LibraryName localLibraryName = LibraryName(<String>['local']);
+    const LibraryName remoteLibraryName = LibraryName(<String>['remote']);
+    final Runtime runtime = Runtime();
+    addTearDown(runtime.dispose);
+    final DynamicContent data = DynamicContent();
+    final Finder textFinder = find.byType(Text);
+
+    runtime.update(coreLibraryName, createCoreWidgets());
+    runtime.update(
+        localLibraryName,
+        LocalWidgetLibrary(<String, LocalWidgetBuilder>{
+          'Builder': (BuildContext context, DataSource source) {
+            return source.builder(
+              <String>['builder'],
+              <String, Object?>{
+                'values': <String>['Value1', 'Value2', 'Value3'],
+              },
+            );
+          },
+        }));
+    runtime.update(remoteLibraryName, parseLibraryFile('''
+      import core;
+      import local;
+
+      widget test = Builder(
+        builder: (scope) =>
+          Column(
+            children: [
+              ...for value in scope.values:
+                Text(text: value, textDirection: 'ltr'),
+            ],
+          ),
+      );
+    '''));
+    await tester.pumpWidget(RemoteWidget(
+      runtime: runtime,
+      data: data,
+      widget: const FullyQualifiedWidgetName(remoteLibraryName, 'test'),
+    ));
+
+    expect(textFinder, findsNWidgets(3));
+    expect((textFinder.at(0).evaluate().first.widget as Text).data, 'Value1');
+    expect((textFinder.at(1).evaluate().first.widget as Text).data, 'Value2');
+    expect((textFinder.at(2).evaluate().first.widget as Text).data, 'Value3');
+  });
 }
 
 final class RfwEvent {