Addressed TODOs added tests.

Author: gspencergoog

packages/spikes/gulf_client/gulf_schema.json

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import '../utils/json_utils.dart';
+
 /// An exception that is thrown when an unknown component type is encountered.
 class UnknownComponentException implements Exception {
   UnknownComponentException(this.type);
@@ -25,7 +27,7 @@ class Component {
   factory Component.fromJson(Map<String, dynamic> json) {
     return Component(
       id: json['id'] as String,
-      weight: (json['weight'] as num?)?.toDouble(),
+      weight: JsonUtils.parseDouble(json['weight']),
       componentProperties: ComponentProperties.fromJson(
         json['componentProperties'] as Map<String, dynamic>,
       ),
@@ -291,7 +293,7 @@ class DividerProperties implements ComponentProperties {
     return DividerProperties(
       axis: json['axis'] as String?,
       color: json['color'] as String?,
-      thickness: (json['thickness'] as num?)?.toDouble(),
+      thickness: JsonUtils.parseDouble(json['thickness']),
     );
   }
 
@@ -463,8 +465,8 @@ class SliderProperties implements ComponentProperties {
   factory SliderProperties.fromJson(Map<String, dynamic> json) {
     return SliderProperties(
       value: BoundValue.fromJson(json['value'] as Map<String, dynamic>),
-      minValue: (json['minValue'] as num?)?.toDouble(),
-      maxValue: (json['maxValue'] as num?)?.toDouble(),
+      minValue: JsonUtils.parseDouble(json['minValue']),
+      maxValue: JsonUtils.parseDouble(json['maxValue']),
     );
   }
 
@@ -491,7 +493,7 @@ class BoundValue {
     return BoundValue(
       path: json['path'] as String?,
       literalString: json['literalString'] as String?,
-      literalNumber: (json['literalNumber'] as num?)?.toDouble(),
+      literalNumber: JsonUtils.parseDouble(json['literalNumber']),
       literalBoolean: json['literalBoolean'] as bool?,
     );
   }

packages/spikes/gulf_client/lib/src/models/component.dart

@@ -0,0 +1,14 @@
+// Copyright 2025 The Flutter Authors.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/// A utility class for handling JSON parsing.
+class JsonUtils {
+  /// Safely parses a [value] to a [double].
+  static double? parseDouble(Object? value) {
+    if (value is num) {
+      return value.toDouble();
+    }
+    return null;
+  }
+}

packages/spikes/gulf_client/lib/src/utils/json_utils.dart

@@ -0,0 +1,93 @@
+// Copyright 2025 The Flutter Authors.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import '../models/component.dart';
+import '../core/interpreter.dart';
+
+/// A visitor that resolves the properties of a [Component].
+class ComponentPropertiesVisitor {
+  /// Creates a new [ComponentPropertiesVisitor].
+  const ComponentPropertiesVisitor(this.interpreter);
+
+  /// The interpreter to use for resolving data bindings.
+  final GulfInterpreter interpreter;
+
+  /// Resolves the properties of a [component].
+  Map<String, Object?> visit(
+    ComponentProperties properties,
+    Map<String, dynamic>? itemData,
+  ) {
+    return switch (properties) {
+      TextProperties() => {'text': _resolveValue(properties.text, itemData)},
+      HeadingProperties() => {
+          'text': _resolveValue(properties.text, itemData),
+          'level': properties.level,
+        },
+      ImageProperties() => {'url': _resolveValue(properties.url, itemData)},
+      VideoProperties() => {'url': _resolveValue(properties.url, itemData)},
+      AudioPlayerProperties() => {
+          'url': _resolveValue(properties.url, itemData),
+          'description': _resolveValue(properties.description, itemData),
+        },
+      ButtonProperties() => {
+          'label': _resolveValue(properties.label, itemData),
+          'action': properties.action,
+        },
+      CheckBoxProperties() => {
+          'label': _resolveValue(properties.label, itemData),
+          'value': _resolveValue(properties.value, itemData),
+        },
+      TextFieldProperties() => {
+          'text': _resolveValue(properties.text, itemData),
+          'label': _resolveValue(properties.label, itemData),
+          'type': properties.type,
+          'validationRegexp': properties.validationRegexp,
+        },
+      DateTimeInputProperties() => {
+          'value': _resolveValue(properties.value, itemData),
+          'enableDate': properties.enableDate,
+          'enableTime': properties.enableTime,
+          'outputFormat': properties.outputFormat,
+        },
+      MultipleChoiceProperties() => {
+          'selections': _resolveValue(properties.selections, itemData),
+          'options': properties.options,
+          'maxAllowedSelections': properties.maxAllowedSelections,
+        },
+      SliderProperties() => {
+          'value': _resolveValue(properties.value, itemData),
+          'minValue': properties.minValue,
+          'maxValue': properties.maxValue,
+        },
+      RowProperties() => {},
+      ColumnProperties() => {},
+      ListProperties() => {},
+      CardProperties() => {},
+      TabsProperties() => {},
+      DividerProperties() => {},
+      ModalProperties() => {},
+      _ => {},
+    };
+  }
+
+  Object? _resolveValue(BoundValue? value, Map<String, dynamic>? itemData) {
+    if (value == null) {
+      return null;
+    }
+    if (value.literalString != null) {
+      return value.literalString;
+    } else if (value.literalNumber != null) {
+      return value.literalNumber;
+    } else if (value.literalBoolean != null) {
+      return value.literalBoolean;
+    } else if (value.path != null) {
+      if (itemData != null) {
+        return itemData[value.path!];
+      } else {
+        return interpreter.resolveDataBinding(value.path!);
+      }
+    }
+    return null;
+  }
+}

packages/spikes/gulf_client/lib/src/widgets/component_properties_visitor.dart

@@ -6,6 +6,7 @@ import 'package:flutter/material.dart';
 import '../core/interpreter.dart';
 import '../core/widget_registry.dart';
 import '../models/component.dart';
+import 'component_properties_visitor.dart';
 import 'gulf_provider.dart';
 
 /// The main entry point for rendering a UI from the GULF Streaming Protocol.
@@ -136,52 +137,8 @@ class _LayoutEngine extends StatelessWidget {
       children['child'] = [_buildNode(context, properties.child, newVisited)];
     }
 
-    final resolvedProperties = <String, Object?>{};
-    // TODO(gspencergoog): find a more generic way to do this.
-    if (properties is TextProperties) {
-      resolvedProperties['text'] = _resolveValue(properties.text, null);
-    } else if (properties is HeadingProperties) {
-      resolvedProperties['text'] = _resolveValue(properties.text, null);
-      resolvedProperties['level'] = properties.level;
-    } else if (properties is ImageProperties) {
-      resolvedProperties['url'] = _resolveValue(properties.url, null);
-    } else if (properties is VideoProperties) {
-      resolvedProperties['url'] = _resolveValue(properties.url, null);
-    } else if (properties is AudioPlayerProperties) {
-      resolvedProperties['url'] = _resolveValue(properties.url, null);
-      resolvedProperties['description'] = _resolveValue(
-        properties.description,
-        null,
-      );
-    } else if (properties is ButtonProperties) {
-      resolvedProperties['label'] = _resolveValue(properties.label, null);
-      resolvedProperties['action'] = properties.action;
-    } else if (properties is CheckBoxProperties) {
-      resolvedProperties['label'] = _resolveValue(properties.label, null);
-      resolvedProperties['value'] = _resolveValue(properties.value, null);
-    } else if (properties is TextFieldProperties) {
-      resolvedProperties['text'] = _resolveValue(properties.text, null);
-      resolvedProperties['label'] = _resolveValue(properties.label, null);
-      resolvedProperties['type'] = properties.type;
-      resolvedProperties['validationRegexp'] = properties.validationRegexp;
-    } else if (properties is DateTimeInputProperties) {
-      resolvedProperties['value'] = _resolveValue(properties.value, null);
-      resolvedProperties['enableDate'] = properties.enableDate;
-      resolvedProperties['enableTime'] = properties.enableTime;
-      resolvedProperties['outputFormat'] = properties.outputFormat;
-    } else if (properties is MultipleChoiceProperties) {
-      resolvedProperties['selections'] = _resolveValue(
-        properties.selections,
-        null,
-      );
-      resolvedProperties['options'] = properties.options;
-      resolvedProperties['maxAllowedSelections'] =
-          properties.maxAllowedSelections;
-    } else if (properties is SliderProperties) {
-      resolvedProperties['value'] = _resolveValue(properties.value, null);
-      resolvedProperties['minValue'] = properties.minValue;
-      resolvedProperties['maxValue'] = properties.maxValue;
-    }
+    final visitor = ComponentPropertiesVisitor(interpreter);
+    final resolvedProperties = visitor.visit(properties, null);
 
     return builder(context, component, resolvedProperties, children);
   }
@@ -212,15 +169,11 @@ class _LayoutEngine extends StatelessWidget {
       );
     }
     final children = data.map((Object? itemData) {
-      final resolvedProperties = <String, Object?>{};
-      final templateProperties = templateComponent.componentProperties;
-      if (templateProperties is TextProperties) {
-        resolvedProperties['text'] = _resolveValue(
-          templateProperties.text,
-          itemData as Map<String, Object?>,
-        );
-      }
-      // TODO(gspencer): Add all other properties types here.
+      final visitor = ComponentPropertiesVisitor(interpreter);
+      final resolvedProperties = visitor.visit(
+        templateComponent.componentProperties,
+        itemData as Map<String, Object?>,
+      );
       final itemChildren = <String, List<Widget>>{};
       final itemBuilder = registry.getBuilder(
         templateComponent.componentProperties.runtimeType.toString(),

packages/spikes/gulf_client/lib/src/widgets/gulf_view.dart

@@ -24,5 +24,6 @@ dev_dependencies:
     sdk: flutter
   freezed: ^3.2.3
   json_serializable: ^6.11.1
+  mockito: ^5.5.1
 
 flutter:

packages/spikes/gulf_client/pubspec.yaml

@@ -0,0 +1,47 @@
+// Copyright 2025 The Flutter Authors.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:gulf_client/src/models/component.dart';
+import 'package:gulf_client/src/widgets/component_properties_visitor.dart';
+
+import 'fakes.dart';
+
+void main() {
+  group('ComponentPropertiesVisitor', () {
+    late FakeGulfInterpreter fakeInterpreter;
+    late ComponentPropertiesVisitor visitor;
+
+    setUp(() {
+      fakeInterpreter = FakeGulfInterpreter();
+      visitor = ComponentPropertiesVisitor(fakeInterpreter);
+    });
+
+    test('visit TextProperties with literal value', () {
+      const properties = TextProperties(
+        text: BoundValue(literalString: 'Hello'),
+      );
+      final result = visitor.visit(properties, null);
+      expect(result, {'text': 'Hello'});
+    });
+
+    test('visit TextProperties with bound value', () {
+      fakeInterpreter.onResolveDataBinding('path.to.text', 'World');
+      const properties = TextProperties(
+        text: BoundValue(path: 'path.to.text'),
+      );
+      final result = visitor.visit(properties, null);
+      expect(result, {'text': 'World'});
+    });
+
+    test('visit HeadingProperties', () {
+      const properties = HeadingProperties(
+        text: BoundValue(literalString: 'Title'),
+        level: 'h1',
+      );
+      final result = visitor.visit(properties, null);
+      expect(result, {'text': 'Title', 'level': 'h1'});
+    });
+  });
+}

packages/spikes/gulf_client/test/component_properties_visitor_test.dart

@@ -0,0 +1,42 @@
+// Copyright 2025 The Flutter Authors.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/foundation.dart';
+import 'package:gulf_client/src/core/interpreter.dart';
+import 'package:gulf_client/src/models/component.dart';
+
+class FakeGulfInterpreter extends ChangeNotifier implements GulfInterpreter {
+  final Map<String, Object?> _data = {};
+
+  void onResolveDataBinding(String path, Object? value) {
+    _data[path] = value;
+  }
+
+  @override
+  Object? resolveDataBinding(String path) {
+    return _data[path];
+  }
+
+  @override
+  String? get error => throw UnimplementedError();
+
+  @override
+  bool get isReadyToRender => throw UnimplementedError();
+
+  @override
+  void processMessage(String jsonl) {
+    throw UnimplementedError();
+  }
+
+  @override
+  String? get rootComponentId => throw UnimplementedError();
+
+  @override
+  Stream<String> get stream => throw UnimplementedError();
+
+  @override
+  Component? getComponent(String id) {
+    throw UnimplementedError();
+  }
+}

packages/spikes/gulf_client/test/fakes.dart

@@ -0,0 +1,26 @@
+// Copyright 2025 The Flutter Authors.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:gulf_client/src/utils/json_utils.dart';
+
+void main() {
+  group('JsonUtils', () {
+    test('parseDouble returns double for int', () {
+      expect(JsonUtils.parseDouble(1), 1.0);
+    });
+
+    test('parseDouble returns double for double', () {
+      expect(JsonUtils.parseDouble(1.5), 1.5);
+    });
+
+    test('parseDouble returns null for non-num', () {
+      expect(JsonUtils.parseDouble('a'), isNull);
+    });
+
+    test('parseDouble returns null for null', () {
+      expect(JsonUtils.parseDouble(null), isNull);
+    });
+  });
+}