Add integration test: hot reload + incremental compiler

utils/kernel-service/kernel-service.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// This is an interface to the Dart Kernel parser and Kernel binary generator.
 ///
 /// It is used by the kernel-isolate to load Dart source code and generate
 /// Kernel binary format.
 ///
 /// This is either invoked as the root script of the Kernel isolate when used
@@ skipping 11 matching lines @@
 
 import 'dart:async';
 import 'dart:io' hide FileSystemEntity;
 import 'dart:isolate';
 
 import 'package:front_end/file_system.dart';
 import 'package:front_end/memory_file_system.dart';
 import 'package:front_end/physical_file_system.dart';
 import 'package:front_end/src/fasta/vm.dart'
     show CompilationResult, Status, parseScriptInFileSystem;
+import 'package:front_end/src/testing/hybrid_file_system.dart';
 
 const bool verbose = const bool.fromEnvironment('DFE_VERBOSE');
 
 const bool strongMode = const bool.fromEnvironment('DFE_STRONG_MODE');
 
 Future<CompilationResult> _processLoadRequestImpl(
     String inputFilePathOrUri, FileSystem fileSystem) {
   Uri scriptUri = Uri.parse(inputFilePathOrUri);
 
   // Because we serve both Loader and bootstrapping requests we need to
@@ skipping 65 matching lines @@
 FileSystem _buildFileSystem(List namedSources) {
   MemoryFileSystem fileSystem = new MemoryFileSystem(Uri.parse('file:///'));
   for (int i = 0; i < namedSources.length ~/ 2; i++) {
     fileSystem
         .entityForUri(Uri.parse(namedSources[i * 2]))
         .writeAsBytesSync(namedSources[i * 2 + 1]);
   }
   return new HybridFileSystem(fileSystem);
 }
 
-/// A file system that mixes files from memory and a physical file system. All
-/// memory entities take priotity over file system entities.
-class HybridFileSystem implements FileSystem {
-  final MemoryFileSystem memory;
-  final PhysicalFileSystem physical = PhysicalFileSystem.instance;
-
-  HybridFileSystem(this.memory);
-
-  @override
-  FileSystemEntity entityForUri(Uri uri) => new HybridFileSystemEntity(
-      memory.entityForUri(uri), physical.entityForUri(uri));
-}
-
-/// Entity that delegates to an underlying memory or phisical file system
-/// entity.
-class HybridFileSystemEntity implements FileSystemEntity {
-  final FileSystemEntity memory;
-  final FileSystemEntity physical;
-
-  HybridFileSystemEntity(this.memory, this.physical);
-
-  FileSystemEntity _delegate;
-  Future<FileSystemEntity> get delegate async {
-    return _delegate ??= (await memory.exists()) ? memory : physical;
-  }
-
-  @override
-  Uri get uri => memory.uri;
-
-  @override
-  Future<bool> exists() async => (await delegate).exists();
-
-  @override
-  Future<DateTime> lastModified() async => (await delegate).lastModified();
-
-  @override
-  Future<List<int>> readAsBytes() async => (await delegate).readAsBytes();
-
-  @override
-  Future<String> readAsString() async => (await delegate).readAsString();
-}
-
 train(String scriptUri) {
   // TODO(28532): Enable on Windows.
   if (Platform.isWindows) return;
 
   var tag = 1;
   var responsePort = new RawReceivePort();
   responsePort.handler = (response) {
     if (response[0] == tag) {
       // Success.
       responsePort.close();
@@ skipping 11 matching lines @@
 main([args]) {
   if (args?.length == 2 && args[0] == '--train') {
     // This entry point is used when creating an app snapshot. The argument
     // provides a script to compile to warm-up generated code.
     train(args[1]);
   } else {
     // Entry point for the Kernel isolate.
     return new RawReceivePort()..handler = _processLoadRequest;
   }
 }