[cupertino_ui] Re-enable tab_scaffold_test.dart (#12064)

This test re-enables `tab_scaffold_test.dart`, and brings over `widget_inspector_test_utils.dart` into `tests/`.

## Pre-Review Checklist

Author: Renzo-Olivares

…ly_disabled_tests/tab_scaffold_test.dart …cupertino_ui/test/tab_scaffold_test.dartpackages/cupertino_ui/temporarily_disabled_tests/tab_scaffold_test.dart renamed to packages/cupertino_ui/test/tab_scaffold_test.dart packages/cupertino_ui/temporarily_disabled_tests/tab_scaffold_test.dart renamed to packages/cupertino_ui/test/tab_scaffold_test.dart

@@ -2,16 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-@Skip(
-  'This file is skipped due to a cross-import that needs to be fixed. Tracked in https://github.com/flutter/flutter/issues/177028.',
-)
 import 'package:cupertino_ui/cupertino_ui.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 
-import '../widgets/widget_inspector_test_utils.dart';
 import 'navigator_utils.dart';
+import 'widget_inspector_test_utils.dart';
 
 late List<int> selectedTabs;
 

packages/cupertino_ui/test/widget_inspector_test_utils.dart

@@ -0,0 +1,121 @@
+// Copyright 2013 The Flutter Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:convert';
+
+import 'package:cupertino_ui/cupertino_ui.dart';
+import 'package:flutter/foundation.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+/// Tuple-like test class for storing a [stream] and [eventKind].
+///
+/// Used to store the [stream] and [eventKind] that a dispatched event would be
+/// sent on.
+@immutable
+class DispatchedEventKey {
+  const DispatchedEventKey({required this.stream, required this.eventKind});
+
+  final String stream;
+  final String eventKind;
+
+  @override
+  String toString() {
+    return '[DispatchedEventKey]($stream, $eventKind)';
+  }
+
+  @override
+  bool operator ==(Object other) {
+    return other is DispatchedEventKey && stream == other.stream && eventKind == other.eventKind;
+  }
+
+  @override
+  int get hashCode => Object.hash(stream, eventKind);
+}
+
+class TestWidgetInspectorService extends Object with WidgetInspectorService {
+  TestWidgetInspectorService() {
+    selection.addListener(() => selectionChangedCallback?.call());
+  }
+
+  final Map<String, ServiceExtensionCallback> extensions = <String, ServiceExtensionCallback>{};
+
+  final Map<DispatchedEventKey, List<Map<Object, Object?>>> eventsDispatched =
+      <DispatchedEventKey, List<Map<Object, Object?>>>{};
+
+  final List<Object?> objectsInspected = <Object?>[];
+
+  @override
+  void registerServiceExtension({
+    required String name,
+    required ServiceExtensionCallback callback,
+    required RegisterServiceExtensionCallback registerExtension,
+  }) {
+    assert(!extensions.containsKey(name));
+    extensions[name] = callback;
+  }
+
+  @override
+  void postEvent(String eventKind, Map<Object, Object?> eventData, {String stream = 'Extension'}) {
+    dispatchedEvents(eventKind, stream: stream).add(eventData);
+  }
+
+  @override
+  void inspect(Object? object) {
+    objectsInspected.add(object);
+  }
+
+  List<Map<Object, Object?>> dispatchedEvents(String eventKind, {String stream = 'Extension'}) {
+    return eventsDispatched.putIfAbsent(
+      DispatchedEventKey(stream: stream, eventKind: eventKind),
+      () => <Map<Object, Object?>>[],
+    );
+  }
+
+  List<Object?> inspectedObjects() {
+    return objectsInspected;
+  }
+
+  Iterable<Map<Object, Object?>> getServiceExtensionStateChangedEvents(String extensionName) {
+    return dispatchedEvents(
+      'Flutter.ServiceExtensionStateChanged',
+    ).where((Map<Object, Object?> event) => event['extension'] == extensionName);
+  }
+
+  Future<Object?> testExtension(String name, Map<String, String> arguments) async {
+    expect(extensions, contains(name));
+    // Encode and decode to JSON to match behavior using a real service
+    // extension where only JSON is allowed.
+    return (json.decode(json.encode(await extensions[name]!(arguments)))
+        as Map<String, dynamic>)['result'];
+  }
+
+  Future<String> testBoolExtension(String name, Map<String, String> arguments) async {
+    expect(extensions, contains(name));
+    // Encode and decode to JSON to match behavior using a real service
+    // extension where only JSON is allowed.
+    return (json.decode(json.encode(await extensions[name]!(arguments)))
+            as Map<String, dynamic>)['enabled']
+        .toString();
+  }
+
+  int rebuildCount = 0;
+
+  @override
+  Future<void> forceRebuild() async {
+    rebuildCount++;
+    final WidgetsBinding binding = WidgetsBinding.instance;
+
+    if (binding.rootElement != null) {
+      binding.buildOwner!.reassemble(binding.rootElement!);
+    }
+  }
+
+  @override
+  void resetAllState() {
+    super.resetAllState();
+    eventsDispatched.clear();
+    objectsInspected.clear();
+    rebuildCount = 0;
+  }
+}