dev/benchmarks/complex_layout/test_driver/semantics_perf_test.dart

// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:async';
import 'dart:convert';
import 'dart:io';

import 'package:flutter_driver/flutter_driver.dart';
import 'package:path/path.dart' as p;
import 'package:test/test.dart' hide TypeMatcher, isInstanceOf;

void main() {
  group('semantics performance test', () {
    late FlutterDriver driver;

    setUpAll(() async {
      driver = await FlutterDriver.connect(printCommunication: true);
    });

    tearDownAll(() async {
      if (driver != null)
        driver.close();
    });

    test('initial tree creation', () async {
      // Let app become fully idle.
      await Future<void>.delayed(const Duration(seconds: 2));

      await driver.forceGC();

      final Timeline timeline = await driver.traceAction(() async {
        expect(await driver.setSemantics(true), isTrue);
      });

      final Iterable<TimelineEvent>? semanticsEvents = timeline.events?.where((TimelineEvent event) => event.name == 'Semantics');
      if (semanticsEvents?.length != 2)
        fail('Expected exactly two semantics events, got ${semanticsEvents?.length}');
      final Duration semanticsTreeCreation = Duration(microseconds: semanticsEvents!.last.timestampMicros! - semanticsEvents.first.timestampMicros!);

      final String jsonEncoded = json.encode(<String, dynamic>{'initialSemanticsTreeCreation': semanticsTreeCreation.inMilliseconds});
      File(p.join(testOutputsDirectory, 'complex_layout_semantics_perf.json')).writeAsStringSync(jsonEncoded);
    }, timeout: Timeout.none);
  });
}