Autocomplete Split UI (#72553)

Allows passing in a TextEditingController and FocusNode to RawAutocomplete, which enables split UIs where the TextField is in another part of the tree from the results.

packages/flutter/test/widgets/autocomplete_test.dart

@@ -45,7 +45,6 @@ void main() {
     User(name: 'Charlie', email: 'charlie123@gmail.com'),
   ];
 
-  group('RawAutocomplete', () {
   testWidgets('can filter and select a list of string options', (WidgetTester tester) async {
     final GlobalKey fieldKey = GlobalKey();
     final GlobalKey optionsKey = GlobalKey();
@@ -327,6 +326,9 @@ void main() {
       ),
     );
 
+    expect(find.byKey(fieldKey), findsOneWidget);
+    expect(find.byKey(optionsKey), findsNothing);
+
     // Enter text. The options are filtered by the text.
     focusNode.requestFocus();
     textEditingController.value = const TextEditingValue(
@@ -486,5 +488,70 @@ void main() {
     expect(lastOptions.elementAt(0), 'chameleon');
     expect(lastOptions.elementAt(1), 'elephant');
   });
+
+  testWidgets('can create a field outside of fieldViewBuilder', (WidgetTester tester) async {
+    final GlobalKey fieldKey = GlobalKey();
+    final GlobalKey optionsKey = GlobalKey();
+    final GlobalKey autocompleteKey = GlobalKey();
+    late Iterable<String> lastOptions;
+    final FocusNode focusNode = FocusNode();
+    final TextEditingController textEditingController = TextEditingController();
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          appBar: AppBar(
+            // This is where the real field is being built.
+            title: TextFormField(
+              key: fieldKey,
+              controller: textEditingController,
+              focusNode: focusNode,
+              onFieldSubmitted: (String value) {
+                RawAutocomplete.onFieldSubmitted(autocompleteKey);
+              },
+            ),
+          ),
+          body: RawAutocomplete<String>(
+            key: autocompleteKey,
+            focusNode: focusNode,
+            textEditingController: textEditingController,
+            optionsBuilder: (TextEditingValue textEditingValue) {
+              return kOptions.where((String option) {
+                return option.contains(textEditingValue.text.toLowerCase());
+              });
+            },
+            optionsViewBuilder: (BuildContext context, AutocompleteOnSelected<String> onSelected, Iterable<String> options) {
+              lastOptions = options;
+              return Container(key: optionsKey);
+            },
+          ),
+        ),
+      ),
+    );
+
+    expect(find.byKey(fieldKey), findsOneWidget);
+    expect(find.byKey(optionsKey), findsNothing);
+
+    // Enter text. The options are filtered by the text.
+    focusNode.requestFocus();
+    textEditingController.value = const TextEditingValue(
+      text: 'ele',
+      selection: TextSelection(baseOffset: 3, extentOffset: 3),
+    );
+    await tester.pump();
+    expect(find.byKey(fieldKey), findsOneWidget);
+    expect(find.byKey(optionsKey), findsOneWidget);
+    expect(lastOptions.length, 2);
+    expect(lastOptions.elementAt(0), 'chameleon');
+    expect(lastOptions.elementAt(1), 'elephant');
+
+    // Submit the field. The options hide and the field updates to show the
+    // selection.
+    await tester.showKeyboard(find.byType(TextFormField));
+    await tester.testTextInput.receiveAction(TextInputAction.done);
+    await tester.pump();
+    expect(find.byKey(fieldKey), findsOneWidget);
+    expect(find.byKey(optionsKey), findsNothing);
+    expect(textEditingController.text, lastOptions.elementAt(0));
   });
 }