[flutter_tools] remove globals from flutter web platform (#70863)

packages/flutter_tools/lib/src/test/flutter_web_goldens.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.
+
+// ignore_for_file: implementation_imports
+
+import 'dart:async';
+import 'dart:typed_data';
+
+import '../base/common.dart';
+import '../base/file_system.dart';
+import '../base/io.dart';
+import '../convert.dart';
+import '../globals.dart' as globals;
+import 'test_compiler.dart';
+import 'test_config.dart';
+
+/// Helper class to start golden file comparison in a separate process.
+///
+/// Golden file comparator is configured using flutter_test_config.dart and that
+/// file can contain arbitrary Dart code that depends on dart:ui. Thus it has to
+/// be executed in a `flutter_tester` environment. This helper class generates a
+/// Dart file configured with flutter_test_config.dart to perform the comparison
+/// of golden files.
+class TestGoldenComparator {
+  /// Creates a [TestGoldenComparator] instance.
+  TestGoldenComparator(this.shellPath, this.compilerFactory)
+      : tempDir = globals.fs.systemTempDirectory.createTempSync('flutter_web_platform.');
+
+  final String shellPath;
+  final Directory tempDir;
+  final TestCompiler Function() compilerFactory;
+
+  TestCompiler _compiler;
+  TestGoldenComparatorProcess _previousComparator;
+  Uri _previousTestUri;
+
+  Future<void> close() async {
+    tempDir.deleteSync(recursive: true);
+    await _compiler?.dispose();
+    await _previousComparator?.close();
+  }
+
+  /// Start golden comparator in a separate process. Start one file per test file
+  /// to reduce the overhead of starting `flutter_tester`.
+  Future<TestGoldenComparatorProcess> _processForTestFile(Uri testUri) async {
+    if (testUri == _previousTestUri) {
+      return _previousComparator;
+    }
+
+    final String bootstrap = TestGoldenComparatorProcess.generateBootstrap(testUri);
+    final Process process = await _startProcess(bootstrap);
+    unawaited(_previousComparator?.close());
+    _previousComparator = TestGoldenComparatorProcess(process);
+    _previousTestUri = testUri;
+
+    return _previousComparator;
+  }
+
+  Future<Process> _startProcess(String testBootstrap) async {
+    // Prepare the Dart file that will talk to us and start the test.
+    final File listenerFile = (await tempDir.createTemp('listener')).childFile('listener.dart');
+    await listenerFile.writeAsString(testBootstrap);
+
+    // Lazily create the compiler
+    _compiler = _compiler ?? compilerFactory();
+    final String output = await _compiler.compile(listenerFile.uri);
+    final List<String> command = <String>[
+      shellPath,
+      '--disable-observatory',
+      '--non-interactive',
+      '--packages=${globals.fs.path.join('.dart_tool', 'package_config.json')}',
+      output,
+    ];
+
+    final Map<String, String> environment = <String, String>{
+      // Chrome is the only supported browser currently.
+      'FLUTTER_TEST_BROWSER': 'chrome',
+    };
+    return globals.processManager.start(command, environment: environment);
+  }
+
+  Future<String> compareGoldens(Uri testUri, Uint8List bytes, Uri goldenKey, bool updateGoldens) async {
+    final File imageFile = await (await tempDir.createTemp('image')).childFile('image').writeAsBytes(bytes);
+    final TestGoldenComparatorProcess process = await _processForTestFile(testUri);
+    process.sendCommand(imageFile, goldenKey, updateGoldens);
+
+    final Map<String, dynamic> result = await process.getResponse();
+
+    if (result == null) {
+      return 'unknown error';
+    } else {
+      return (result['success'] as bool) ? null : ((result['message'] as String) ?? 'does not match');
+    }
+  }
+}
+
+/// Represents a `flutter_tester` process started for golden comparison. Also
+/// handles communication with the child process.
+class TestGoldenComparatorProcess {
+  /// Creates a [TestGoldenComparatorProcess] backed by [process].
+  TestGoldenComparatorProcess(this.process) {
+    // Pipe stdout and stderr to printTrace and printError.
+    // Also parse stdout as a stream of JSON objects.
+    streamIterator = StreamIterator<Map<String, dynamic>>(
+      process.stdout
+        .transform<String>(utf8.decoder)
+        .transform<String>(const LineSplitter())
+        .where((String line) {
+          globals.printTrace('<<< $line');
+          return line.isNotEmpty && line[0] == '{';
+        })
+        .map<dynamic>(jsonDecode)
+        .cast<Map<String, dynamic>>());
+
+    process.stderr
+        .transform<String>(utf8.decoder)
+        .transform<String>(const LineSplitter())
+        .forEach((String line) {
+          globals.printError('<<< $line');
+        });
+  }
+
+  final Process process;
+  StreamIterator<Map<String, dynamic>> streamIterator;
+
+  Future<void> close() async {
+    await process.stdin.close();
+    process.kill();
+  }
+
+  void sendCommand(File imageFile, Uri goldenKey, bool updateGoldens) {
+    final Object command = jsonEncode(<String, dynamic>{
+      'imageFile': imageFile.path,
+      'key': goldenKey.toString(),
+      'update': updateGoldens,
+    });
+    globals.printTrace('Preparing to send command: $command');
+    process.stdin.writeln(command);
+  }
+
+  Future<Map<String, dynamic>> getResponse() async {
+    final bool available = await streamIterator.moveNext();
+    assert(available);
+    return streamIterator.current;
+  }
+
+  static String generateBootstrap(Uri testUri) {
+    final File testConfigFile = findTestConfigFile(globals.fs.file(testUri));
+    // Generate comparator process for the file.
+    return '''
+// @dart=2.9
+import 'dart:convert'; // ignore: dart_convert_import
+import 'dart:io'; // ignore: dart_io_import
+
+import 'package:flutter_test/flutter_test.dart';
+
+${testConfigFile != null ? "import '${Uri.file(testConfigFile.path)}' as test_config;" : ""}
+
+void main() async {
+  LocalFileComparator comparator = LocalFileComparator(Uri.parse('$testUri'));
+  goldenFileComparator = comparator;
+
+  ${testConfigFile != null ? 'test_config.testExecutable(() async {' : ''}
+  final commands = stdin
+    .transform<String>(utf8.decoder)
+    .transform<String>(const LineSplitter())
+    .map<Object>(jsonDecode);
+  await for (final Object command in commands) {
+    if (command is Map<String, dynamic>) {
+      File imageFile = File(command['imageFile']);
+      Uri goldenKey = Uri.parse(command['key']);
+      bool update = command['update'];
+
+      final bytes = await File(imageFile.path).readAsBytes();
+      if (update) {
+        await goldenFileComparator.update(goldenKey, bytes);
+        print(jsonEncode({'success': true}));
+      } else {
+        try {
+          bool success = await goldenFileComparator.compare(bytes, goldenKey);
+          print(jsonEncode({'success': success}));
+        } on Exception catch (ex) {
+          print(jsonEncode({'success': false, 'message': '\$ex'}));
+        }
+      }
+    } else {
+      print('object type is not right');
+    }
+  }
+  ${testConfigFile != null ? '});' : ''}
+}
+    ''';
+  }
+}

packages/flutter_tools/lib/src/test/runner.dart

@@ -11,6 +11,7 @@ import '../base/io.dart';
 import '../build_info.dart';
 import '../globals.dart' as globals;
 import '../project.dart';
+import '../web/chrome.dart';
 import '../web/compile.dart';
 import '../web/memory_fs.dart';
 import 'flutter_platform.dart' as loader;
@@ -139,6 +140,8 @@ class _FlutterTestRunnerImpl implements FlutterTestRunner {
       testWrapper.registerPlatformPlugin(
         <Runtime>[Runtime.chrome],
         () {
+          // TODO(jonahwilliams): refactor this into a factory that handles
+          // providing dependencies.
           return FlutterWebPlatform.start(
             flutterProject.directory.path,
             updateGoldens: updateGoldens,
@@ -147,6 +150,17 @@ class _FlutterTestRunnerImpl implements FlutterTestRunner {
             pauseAfterLoad: startPaused,
             buildInfo: buildInfo,
             webMemoryFS: result,
+            logger: globals.logger,
+            fileSystem: globals.fs,
+            artifacts: globals.artifacts,
+            chromiumLauncher: ChromiumLauncher(
+              fileSystem: globals.fs,
+              platform: globals.platform,
+              processManager: globals.processManager,
+              operatingSystemUtils: globals.os,
+              browserFinder: findChromeExecutable,
+              logger: globals.logger,
+            ),
           );
         },
       );

packages/flutter_tools/test/general.shard/web/golden_comparator_process_test.dart

@@ -5,8 +5,8 @@
 import 'dart:convert';
 
 import 'package:flutter_tools/src/base/file_system.dart';
-import 'package:flutter_tools/src/test/flutter_web_platform.dart';
 import 'package:flutter_tools/src/globals.dart' as globals;
+import 'package:flutter_tools/src/test/flutter_web_goldens.dart';
 
 import '../../src/common.dart';
 import '../../src/mocks.dart';

packages/flutter_tools/test/general.shard/web/golden_comparator_test.dart

@@ -5,7 +5,7 @@
 import 'dart:convert';
 import 'dart:typed_data';
 
-import 'package:flutter_tools/src/test/flutter_web_platform.dart';
+import 'package:flutter_tools/src/test/flutter_web_goldens.dart';
 import 'package:flutter_tools/src/test/test_compiler.dart';
 import 'package:flutter_tools/src/globals.dart' as globals;
 import 'package:mockito/mockito.dart';