Fix autocomplete options height (#80187)

packages/flutter/lib/src/material/autocomplete.dart

@@ -166,6 +166,7 @@ class Autocomplete<T extends Object> extends StatelessWidget {
     this.displayStringForOption = RawAutocomplete.defaultStringForOption,
     this.fieldViewBuilder = _defaultFieldViewBuilder,
     this.onSelected,
+    this.optionsMaxHeight = 200.0,
     this.optionsViewBuilder,
     this.initialValue,
   }) : assert(displayStringForOption != null),
@@ -193,6 +194,14 @@ class Autocomplete<T extends Object> extends StatelessWidget {
   /// default.
   final AutocompleteOptionsViewBuilder<T>? optionsViewBuilder;
 
+  /// The maximum height used for the default Material options list widget.
+  ///
+  /// When [optionsViewBuilder] is `null`, this property sets the maximum height
+  /// that the options widget can occupy.
+  ///
+  /// The default value is set to 200.
+  final double optionsMaxHeight;
+
   /// {@macro flutter.widgets.RawAutocomplete.initialValue}
   final TextEditingValue? initialValue;
 
@@ -216,6 +225,7 @@ class Autocomplete<T extends Object> extends StatelessWidget {
           displayStringForOption: displayStringForOption,
           onSelected: onSelected,
           options: options,
+          maxOptionsHeight: optionsMaxHeight,
         );
       },
       onSelected: onSelected,
@@ -257,6 +267,7 @@ class _AutocompleteOptions<T extends Object> extends StatelessWidget {
     required this.displayStringForOption,
     required this.onSelected,
     required this.options,
+    required this.maxOptionsHeight,
   }) : super(key: key);
 
   final AutocompleteOptionToString<T> displayStringForOption;
@@ -264,6 +275,7 @@ class _AutocompleteOptions<T extends Object> extends StatelessWidget {
   final AutocompleteOnSelected<T> onSelected;
 
   final Iterable<T> options;
+  final double maxOptionsHeight;
 
   @override
   Widget build(BuildContext context) {
@@ -271,10 +283,11 @@ class _AutocompleteOptions<T extends Object> extends StatelessWidget {
       alignment: Alignment.topLeft,
       child: Material(
         elevation: 4.0,
-        child: SizedBox(
-          height: 200.0,
+        child: ConstrainedBox(
+          constraints: BoxConstraints(maxHeight: maxOptionsHeight),
           child: ListView.builder(
             padding: EdgeInsets.zero,
+            shrinkWrap: true,
             itemCount: options.length,
             itemBuilder: (BuildContext context, int index) {
               final T option = options.elementAt(index);

packages/flutter/test/material/autocomplete_test.dart

@@ -254,6 +254,104 @@ void main() {
     expect(find.byKey(optionsKey), findsOneWidget);
   });
 
+  testWidgets('the default Autocomplete options widget has a maximum height of 200', (WidgetTester tester) async {
+    await tester.pumpWidget(MaterialApp(home: Scaffold(
+      body: Autocomplete<String>(
+        optionsBuilder: (TextEditingValue textEditingValue) {
+          return kOptions.where((String option) {
+            return option.contains(textEditingValue.text.toLowerCase());
+          });
+        },
+      ),
+    )));
+
+    final Finder listFinder = find.byType(ListView);
+    final Finder inputFinder = find.byType(TextFormField);
+    await tester.tap(inputFinder);
+    await tester.enterText(inputFinder, '');
+    await tester.pump();
+    final Size baseSize = tester.getSize(listFinder);
+    final double resultingHeight = baseSize.height;
+    expect(resultingHeight, equals(200));
+  });
+
+  testWidgets('the options height restricts to max desired height', (WidgetTester tester) async {
+    const double desiredHeight = 150.0;
+    await tester.pumpWidget(MaterialApp(
+      home: Scaffold(
+      body: Autocomplete<String>(
+        optionsMaxHeight: desiredHeight,
+        optionsBuilder: (TextEditingValue textEditingValue) {
+          return kOptions.where((String option) {
+            return option.contains(textEditingValue.text.toLowerCase());
+          });
+        },
+      ),
+    )));
+
+    /// entering "a" returns 9 items from kOptions so basically the
+    /// height of 9 options would be beyond `desiredHeight=150`,
+    /// so height gets restricted to desiredHeight.
+    final Finder listFinder = find.byType(ListView);
+    final Finder inputFinder = find.byType(TextFormField);
+    await tester.tap(inputFinder);
+    await tester.enterText(inputFinder, 'a');
+    await tester.pump();
+    final Size baseSize = tester.getSize(listFinder);
+    final double resultingHeight = baseSize.height;
+
+    /// expected desired Height =150.0
+    expect(resultingHeight, equals(desiredHeight));
+  });
+
+  testWidgets('The height of options shrinks to height of resulting items, if less than maxHeight', (WidgetTester tester) async {
+    // Returns a Future with the height of the default [Autocomplete] options widget
+    // after the provided text had been entered into the [Autocomplete] field.
+    Future<double> _getDefaultOptionsHeight(
+        WidgetTester tester, String enteredText) async {
+      final Finder listFinder = find.byType(ListView);
+      final Finder inputFinder = find.byType(TextFormField);
+      final TextFormField field = inputFinder.evaluate().first.widget as TextFormField;
+      field.controller!.clear();
+      await tester.tap(inputFinder);
+      await tester.enterText(inputFinder, enteredText);
+      await tester.pump();
+      final Size baseSize = tester.getSize(listFinder);
+      return baseSize.height;
+    }
+
+    const double maxOptionsHeight = 250.0;
+    await tester.pumpWidget(MaterialApp(
+      home: Scaffold(
+      body: Autocomplete<String>(
+        optionsMaxHeight: maxOptionsHeight,
+        optionsBuilder: (TextEditingValue textEditingValue) {
+          return kOptions.where((String option) {
+            return option.contains(textEditingValue.text.toLowerCase());
+          });
+        },
+      ),
+    )));
+
+    final Finder listFinder = find.byType(ListView);
+    expect(listFinder, findsNothing);
+
+    /// entering `a` returns 9 items(height > `maxOptionsheight`) from the kOptions
+    /// so height gets restricted to `maxOptionsheight =250`
+    final double nineItemsHeight = await _getDefaultOptionsHeight(tester, 'a');
+    expect(nineItemsHeight, equals(maxOptionsHeight));
+
+    /// returns 2 Items (height < `maxOptionsHeight`)
+    /// so options height shrinks to 2 Items combined height
+    final double twoItemsHeight = await _getDefaultOptionsHeight(tester, 'el');
+    expect(twoItemsHeight, lessThan(maxOptionsHeight));
+
+    /// returns 1 item (height < `maxOptionsHeight`) from `kOptions`
+    /// so options height shrinks to 1 items height
+    final double oneItemsHeight = await _getDefaultOptionsHeight(tester, 'elep');
+    expect(oneItemsHeight, lessThan(twoItemsHeight));
+  });
+
   testWidgets('initialValue sets initial text field value', (WidgetTester tester) async {
     late String lastSelection;
     await tester.pumpWidget(