Revert "Revert "Rollback patch that broke microbenchmarks" (#11641)" (#11645)

This reverts commit 1705bf3c.

packages/flutter_tools/lib/src/base/build.dart

@@ -2,48 +2,11 @@
 // 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' show JSON;
 
 import 'package:crypto/crypto.dart' show md5;
-import 'package:meta/meta.dart';
 
-import '../artifacts.dart';
-import '../build_info.dart';
-import '../globals.dart';
-import 'context.dart';
 import 'file_system.dart';
-import 'process.dart';
-
-GenSnapshot get genSnapshot => context.putIfAbsent(GenSnapshot, () => const GenSnapshot());
-
-class GenSnapshot {
-  const GenSnapshot();
-
-  Future<int> run({
-    @required TargetPlatform targetPlatform,
-    @required BuildMode buildMode,
-    @required String packagesPath,
-    @required String depfilePath,
-    Iterable<String> additionalArgs: const <String>[],
-  }) {
-    final String vmSnapshotData = artifacts.getArtifactPath(Artifact.vmSnapshotData);
-    final String isolateSnapshotData = artifacts.getArtifactPath(Artifact.isolateSnapshotData);
-    final List<String> args = <String>[
-      '--assert_initializer',
-      '--await_is_keyword',
-      '--causal_async_stacks',
-      '--vm_snapshot_data=$vmSnapshotData',
-      '--isolate_snapshot_data=$isolateSnapshotData',
-      '--packages=$packagesPath',
-      '--dependencies=$depfilePath',
-      '--print_snapshot_sizes',
-    ]..addAll(additionalArgs);
-
-    final String snapshotterPath = artifacts.getArtifactPath(Artifact.genSnapshot, targetPlatform, buildMode);
-    return runCommandAndStreamOutput(<String>[snapshotterPath]..addAll(args));
-  }
-}
 
 /// A collection of checksums for a set of input files.
 ///
@@ -79,134 +42,3 @@ class Checksum {
   @override
   int get hashCode => _checksums.hashCode;
 }
-
-final RegExp _separatorExpr = new RegExp(r'([^\\]) ');
-final RegExp _escapeExpr = new RegExp(r'\\(.)');
-
-/// Parses a VM snapshot dependency file.
-///
-/// Snapshot dependency files are a single line mapping the output snapshot to a
-/// space-separated list of input files used to generate that output. Spaces and
-/// backslashes are escaped with a backslash. e.g,
-///
-/// outfile : file1.dart fil\\e2.dart fil\ e3.dart
-///
-/// will return a set containing: 'file1.dart', 'fil\e2.dart', 'fil e3.dart'.
-Future<Set<String>> readDepfile(String depfilePath) async {
-  // Depfile format:
-  // outfile1 outfile2 : file1.dart file2.dart file3.dart
-  final String contents = await fs.file(depfilePath).readAsString();
-  final String dependencies = contents.split(': ')[1];
-  return dependencies
-      .replaceAllMapped(_separatorExpr, (Match match) => '${match.group(1)}\n')
-      .split('\n')
-      .map((String path) => path.replaceAllMapped(_escapeExpr, (Match match) => match.group(1)).trim())
-      .where((String path) => path.isNotEmpty)
-      .toSet();
-}
-
-/// Dart snapshot builder.
-///
-/// Builds Dart snapshots in one of three modes:
-///   * Script snapshot: architecture-independent snapshot of a Dart script core
-///     libraries.
-///   * AOT snapshot: architecture-specific ahead-of-time compiled snapshot
-///     suitable for loading with `mmap`.
-///   * Assembly AOT snapshot: architecture-specific ahead-of-time compile to
-///     assembly suitable for compilation as a static or dynamic library.
-class Snapshotter {
-  /// Builds an architecture-independent snapshot of the specified script.
-  Future<int> buildScriptSnapshot({
-    @required String mainPath,
-    @required String snapshotPath,
-    @required String depfilePath,
-    @required String packagesPath
-  }) async {
-    final List<String> args = <String>[
-      '--snapshot_kind=script',
-      '--script_snapshot=$snapshotPath',
-      mainPath,
-    ];
-
-    final String checksumsPath = '$depfilePath.checksums';
-    final int exitCode = await _build(
-      outputSnapshotPath: snapshotPath,
-      packagesPath: packagesPath,
-      snapshotArgs: args,
-      depfilePath: depfilePath,
-      mainPath: mainPath,
-      checksumsPath: checksumsPath,
-    );
-    if (exitCode != 0)
-      return exitCode;
-    await _writeChecksum(snapshotPath, depfilePath, mainPath, checksumsPath);
-    return exitCode;
-  }
-
-  /// Builds an architecture-specific ahead-of-time compiled snapshot of the specified script.
-  Future<Null> buildAotSnapshot() async {
-    throw new UnimplementedError('AOT snapshotting not yet implemented');
-  }
-
-  Future<int> _build({
-    @required List<String> snapshotArgs,
-    @required String outputSnapshotPath,
-    @required String packagesPath,
-    @required String depfilePath,
-    @required String mainPath,
-    @required String checksumsPath,
-  }) async {
-    if (!await _isBuildRequired(outputSnapshotPath, depfilePath, mainPath, checksumsPath)) {
-      printTrace('Skipping snapshot build. Checksums match.');
-      return 0;
-    }
-
-    // Build the snapshot.
-    final int exitCode = await genSnapshot.run(
-        targetPlatform: null,
-        buildMode: BuildMode.debug,
-        packagesPath: packagesPath,
-        depfilePath: depfilePath,
-        additionalArgs: snapshotArgs,
-    );
-    if (exitCode != 0)
-      return exitCode;
-
-    _writeChecksum(outputSnapshotPath, depfilePath, mainPath, checksumsPath);
-    return 0;
-  }
-
-  Future<bool> _isBuildRequired(String outputSnapshotPath, String depfilePath, String mainPath, String checksumsPath) async {
-    final File checksumFile = fs.file(checksumsPath);
-    final File outputSnapshotFile = fs.file(outputSnapshotPath);
-    final File depfile = fs.file(depfilePath);
-    if (!outputSnapshotFile.existsSync() || !depfile.existsSync() || !checksumFile.existsSync())
-      return true;
-
-    try {
-      if (checksumFile.existsSync()) {
-        final Checksum oldChecksum = new Checksum.fromJson(await checksumFile.readAsString());
-        final Set<String> checksumPaths = await readDepfile(depfilePath)
-          ..addAll(<String>[outputSnapshotPath, mainPath]);
-        final Checksum newChecksum = new Checksum.fromFiles(checksumPaths);
-        return oldChecksum != newChecksum;
-      }
-    } catch (e, s) {
-      // Log exception and continue, this step is a performance improvement only.
-      printTrace('Error during snapshot checksum output: $e\n$s');
-    }
-    return true;
-  }
-
-  Future<Null> _writeChecksum(String outputSnapshotPath, String depfilePath, String mainPath, String checksumsPath) async {
-    try {
-      final Set<String> checksumPaths = await readDepfile(depfilePath)
-        ..addAll(<String>[outputSnapshotPath, mainPath]);
-      final Checksum checksum = new Checksum.fromFiles(checksumPaths);
-      await fs.file(checksumsPath).writeAsString(checksum.toJson());
-    } catch (e, s) {
-      // Log exception and continue, this step is a performance improvement only.
-      print('Error during snapshot checksum output: $e\n$s');
-    }
-  }
-}

packages/flutter_tools/lib/src/commands/build_aot.dart

@@ -5,7 +5,6 @@
 import 'dart:async';
 
 import '../artifacts.dart';
-import '../base/build.dart';
 import '../base/common.dart';
 import '../base/file_system.dart';
 import '../base/logger.dart';
@@ -150,16 +149,13 @@ Future<String> _buildAotSnapshot(
   final String uiPath = fs.path.join(skyEnginePkg, 'lib', 'ui', 'ui.dart');
   final String vmServicePath = fs.path.join(skyEnginePkg, 'sdk_ext', 'vmservice_io.dart');
 
-  final List<String> inputPaths = <String>[
+  final List<String> filePaths = <String>[
     vmEntryPoints,
     ioEntryPoints,
     uiPath,
     vmServicePath,
-    mainPath,
   ];
 
-  final Set<String> outputPaths = new Set<String>();
-
   // These paths are used only on iOS.
   String snapshotDartIOS;
   String assembly;
@@ -168,15 +164,13 @@ Future<String> _buildAotSnapshot(
     case TargetPlatform.android_arm:
     case TargetPlatform.android_x64:
     case TargetPlatform.android_x86:
-      outputPaths.addAll(<String>[
-        vmSnapshotData,
-        isolateSnapshotData,
-      ]);
       break;
     case TargetPlatform.ios:
       snapshotDartIOS = artifacts.getArtifactPath(Artifact.snapshotDart, platform, buildMode);
       assembly = fs.path.join(outputDir.path, 'snapshot_assembly.S');
-      inputPaths.add(snapshotDartIOS);
+      filePaths.addAll(<String>[
+        snapshotDartIOS,
+      ]);
       break;
     case TargetPlatform.darwin_x64:
     case TargetPlatform.linux_x64:
@@ -185,9 +179,9 @@ Future<String> _buildAotSnapshot(
       assert(false);
   }
 
-  final Iterable<String> missingInputs = inputPaths.where((String p) => !fs.isFileSync(p));
-  if (missingInputs.isNotEmpty) {
-    printError('Missing input files: $missingInputs');
+  final List<String> missingFiles = filePaths.where((String p) => !fs.isFileSync(p)).toList();
+  if (missingFiles.isNotEmpty) {
+    printError('Missing files: $missingFiles');
     return null;
   }
   if (!processManager.canRun(genSnapshot)) {
@@ -214,17 +208,6 @@ Future<String> _buildAotSnapshot(
     genSnapshotCmd.add('--embedder_entry_points_manifest=$ioEntryPoints');
   }
 
-  // iOS symbols used to load snapshot data in the engine.
-  const String kVmSnapshotData = 'kDartVmSnapshotData';
-  const String kIsolateSnapshotData = 'kDartIsolateSnapshotData';
-
-  // iOS snapshot generated files, compiled object files.
-  final String kVmSnapshotDataC = fs.path.join(outputDir.path, '$kVmSnapshotData.c');
-  final String kIsolateSnapshotDataC = fs.path.join(outputDir.path, '$kIsolateSnapshotData.c');
-  final String kVmSnapshotDataO = fs.path.join(outputDir.path, '$kVmSnapshotData.o');
-  final String kIsolateSnapshotDataO = fs.path.join(outputDir.path, '$kIsolateSnapshotData.o');
-  final String assemblyO = fs.path.join(outputDir.path, 'snapshot_assembly.o');
-
   switch (platform) {
     case TargetPlatform.android_arm:
     case TargetPlatform.android_x64:
@@ -241,14 +224,9 @@ Future<String> _buildAotSnapshot(
       if (interpreter) {
         genSnapshotCmd.add('--snapshot_kind=core');
         genSnapshotCmd.add(snapshotDartIOS);
-        outputPaths.addAll(<String>[
-          kVmSnapshotDataO,
-          kIsolateSnapshotDataO,
-        ]);
       } else {
         genSnapshotCmd.add('--snapshot_kind=app-aot-assembly');
         genSnapshotCmd.add('--assembly=$assembly');
-        outputPaths.add(assemblyO);
       }
       break;
     case TargetPlatform.darwin_x64:
@@ -267,27 +245,6 @@ Future<String> _buildAotSnapshot(
 
   genSnapshotCmd.add(mainPath);
 
-  final File checksumFile = fs.file('$dependencies.checksum');
-  final List<File> checksumFiles = <File>[checksumFile, fs.file(dependencies)]
-      ..addAll(inputPaths.map(fs.file))
-      ..addAll(outputPaths.map(fs.file));
-  if (checksumFiles.every((File file) => file.existsSync())) {
-    try {
-      final String json = await checksumFile.readAsString();
-      final Checksum oldChecksum = new Checksum.fromJson(json);
-      final Set<String> snapshotInputPaths = await readDepfile(dependencies);
-      snapshotInputPaths.addAll(outputPaths);
-      final Checksum newChecksum = new Checksum.fromFiles(snapshotInputPaths);
-      if (oldChecksum == newChecksum) {
-        printTrace('Skipping AOT snapshot build. Checksums match.');
-        return outputPath;
-      }
-    } catch (e, s) {
-      // Log exception and continue, this step is a performance improvement only.
-      printTrace('Error during AOT snapshot checksum check: $e\n$s');
-    }
-  }
-
   final RunResult results = await runAsync(genSnapshotCmd);
   if (results.exitCode != 0) {
     printError('Dart snapshot generator failed with exit code ${results.exitCode}');
@@ -304,6 +261,16 @@ Future<String> _buildAotSnapshot(
   if (platform == TargetPlatform.ios) {
     printStatus('Building App.framework...');
 
+    // These names are known to from the engine.
+    const String kVmSnapshotData = 'kDartVmSnapshotData';
+    const String kIsolateSnapshotData = 'kDartIsolateSnapshotData';
+
+    final String kVmSnapshotDataC = fs.path.join(outputDir.path, '$kVmSnapshotData.c');
+    final String kIsolateSnapshotDataC = fs.path.join(outputDir.path, '$kIsolateSnapshotData.c');
+    final String kVmSnapshotDataO = fs.path.join(outputDir.path, '$kVmSnapshotData.o');
+    final String kIsolateSnapshotDataO = fs.path.join(outputDir.path, '$kIsolateSnapshotData.o');
+    final String assemblyO = fs.path.join(outputDir.path, 'snapshot_assembly.o');
+
     final List<String> commonBuildOptions = <String>['-arch', 'arm64', '-miphoneos-version-min=8.0'];
 
     if (interpreter) {
@@ -350,16 +317,5 @@ Future<String> _buildAotSnapshot(
     await runCheckedAsync(linkCommand);
   }
 
-  // Compute and record checksums.
-  try {
-    final Set<String> snapshotInputPaths = await readDepfile(dependencies);
-    snapshotInputPaths..addAll(outputPaths);
-    final Checksum checksum = new Checksum.fromFiles(snapshotInputPaths);
-    await checksumFile.writeAsString(checksum.toJson());
-  } catch (e, s) {
-    // Log exception and continue, this step is a performance improvement only.
-    printTrace('Error during AOT snapshot checksum output: $e\n$s');
-  }
-
   return outputPath;
 }

packages/flutter_tools/lib/src/flx.dart

@@ -4,10 +4,14 @@
 
 import 'dart:async';
 
+import 'package:meta/meta.dart' show required;
+
+import 'artifacts.dart';
 import 'asset.dart';
 import 'base/build.dart';
 import 'base/common.dart';
 import 'base/file_system.dart';
+import 'base/process.dart';
 import 'build_info.dart';
 import 'dart/package_map.dart';
 import 'devfs.dart';
@@ -26,6 +30,90 @@ const String _kKernelKey = 'kernel_blob.bin';
 const String _kSnapshotKey = 'snapshot_blob.bin';
 const String _kDylibKey = 'libapp.so';
 
+Future<int> _createSnapshot({
+  @required String mainPath,
+  @required String snapshotPath,
+  @required String depfilePath,
+  @required String packages
+}) async {
+  assert(mainPath != null);
+  assert(snapshotPath != null);
+  assert(depfilePath != null);
+  assert(packages != null);
+  final String snapshotterPath = artifacts.getArtifactPath(Artifact.genSnapshot, null, BuildMode.debug);
+  final String vmSnapshotData = artifacts.getArtifactPath(Artifact.vmSnapshotData);
+  final String isolateSnapshotData = artifacts.getArtifactPath(Artifact.isolateSnapshotData);
+
+  final List<String> args = <String>[
+    snapshotterPath,
+    '--snapshot_kind=script',
+    '--vm_snapshot_data=$vmSnapshotData',
+    '--isolate_snapshot_data=$isolateSnapshotData',
+    '--packages=$packages',
+    '--script_snapshot=$snapshotPath',
+    '--dependencies=$depfilePath',
+    mainPath,
+  ];
+
+  // Write the depfile path to disk.
+  fs.file(depfilePath).parent.childFile('gen_snapshot.d').writeAsString('$depfilePath: $snapshotterPath\n');
+
+  final File checksumFile = fs.file('$depfilePath.checksums');
+  final File snapshotFile = fs.file(snapshotPath);
+  final File depfile = fs.file(depfilePath);
+  if (snapshotFile.existsSync() && depfile.existsSync() && checksumFile.existsSync()) {
+    try {
+        final String json = await checksumFile.readAsString();
+        final Checksum oldChecksum = new Checksum.fromJson(json);
+        final Set<String> inputPaths = await _readDepfile(depfilePath);
+        inputPaths.add(snapshotPath);
+        final Checksum newChecksum = new Checksum.fromFiles(inputPaths);
+        if (oldChecksum == newChecksum) {
+          printTrace('Skipping snapshot build. Checksums match.');
+          return 0;
+        }
+    } catch (e, s) {
+      // Log exception and continue, this step is a performance improvement only.
+      printTrace('Error during snapshot checksum check: $e\n$s');
+    }
+  }
+
+  // Build the snapshot.
+  final int exitCode = await runCommandAndStreamOutput(args);
+  if (exitCode != 0)
+    return exitCode;
+
+  // Compute and record input file checksums.
+  try {
+    final Set<String> inputPaths = await _readDepfile(depfilePath);
+    inputPaths.add(snapshotPath);
+    final Checksum checksum = new Checksum.fromFiles(inputPaths);
+    await checksumFile.writeAsString(checksum.toJson());
+  } catch (e, s) {
+    // Log exception and continue, this step is a performance improvement only.
+    printTrace('Error during snapshot checksum output: $e\n$s');
+  }
+  return 0;
+}
+
+/// Parses a VM snapshot dependency file.
+///
+/// Snapshot dependency files are a single line mapping the output snapshot to a
+/// space-separated list of input files used to generate that output. e.g,
+///
+/// outfile : file1.dart file2.dart file3.dart
+Future<Set<String>> _readDepfile(String depfilePath) async {
+  // Depfile format:
+  // outfile : file1.dart file2.dart file3.dart
+  final String contents = await fs.file(depfilePath).readAsString();
+  final String dependencies = contents.split(': ')[1];
+  return dependencies
+      .split(' ')
+      .map((String path) => path.trim())
+      .where((String path) => path.isNotEmpty)
+      .toSet();
+}
+
 Future<Null> build({
   String mainPath: defaultMainPath,
   String manifestPath: defaultManifestPath,
@@ -51,12 +139,11 @@ Future<Null> build({
 
     // In a precompiled snapshot, the instruction buffer contains script
     // content equivalents
-    final Snapshotter snapshotter = new Snapshotter();
-    final int result = await snapshotter.buildScriptSnapshot(
+    final int result = await _createSnapshot(
       mainPath: mainPath,
       snapshotPath: snapshotPath,
       depfilePath: depfilePath,
-      packagesPath: packagesPath,
+      packages: packagesPath
     );
     if (result != 0)
       throwToolExit('Failed to run the Flutter compiler. Exit code: $result', exitCode: result);

packages/flutter_tools/test/base/build_test.dart

@@ -2,54 +2,13 @@
 // 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' show JSON;
-
 import 'package:file/memory.dart';
 import 'package:flutter_tools/src/base/build.dart';
-import 'package:flutter_tools/src/base/context.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
-import 'package:flutter_tools/src/build_info.dart';
 import 'package:test/test.dart';
 
 import '../src/context.dart';
 
-class _FakeGenSnapshot implements GenSnapshot {
-  _FakeGenSnapshot({
-    this.succeed: true,
-    this.snapshotPath: 'output.snapshot',
-    this.snapshotContent: '',
-    this.depfilePath: 'output.snapshot.d',
-    this.depfileContent: 'output.snapshot.d : main.dart',
-  });
-
-  final bool succeed;
-  final String snapshotPath;
-  final String snapshotContent;
-  final String depfilePath;
-  final String depfileContent;
-  int _callCount = 0;
-
-  int get callCount => _callCount;
-
-  @override
-  Future<int> run({
-    TargetPlatform targetPlatform,
-    BuildMode buildMode,
-    String packagesPath,
-    String depfilePath,
-    Iterable<String> additionalArgs,
-  }) async {
-    _callCount += 1;
-
-    if (!succeed)
-      return 1;
-    await fs.file(snapshotPath).writeAsString(snapshotContent);
-    await fs.file(depfilePath).writeAsString(depfileContent);
-    return 0;
-  }
-}
-
 void main() {
   group('Checksum', () {
     group('fromFiles', () {
@@ -105,185 +64,4 @@ void main() {
       });
     });
   });
-
-  group('readDepfile', () {
-    MemoryFileSystem fs;
-
-    setUp(() {
-      fs = new MemoryFileSystem();
-    });
-
-    testUsingContext('returns one file if only one is listed', () async {
-      await fs.file('a.d').writeAsString('snapshot.d: /foo/a.dart');
-      expect(await readDepfile('a.d'), unorderedEquals(<String>['/foo/a.dart']));
-    }, overrides: <Type, Generator>{ FileSystem: () => fs });
-
-    testUsingContext('returns multiple files', () async {
-      await fs.file('a.d').writeAsString('snapshot.d: /foo/a.dart /foo/b.dart');
-      expect(await readDepfile('a.d'), unorderedEquals(<String>[
-        '/foo/a.dart',
-        '/foo/b.dart',
-      ]));
-    }, overrides: <Type, Generator>{ FileSystem: () => fs});
-
-    testUsingContext('trims extra spaces between files', () async {
-      await fs.file('a.d').writeAsString('snapshot.d: /foo/a.dart    /foo/b.dart  /foo/c.dart');
-      expect(await readDepfile('a.d'), unorderedEquals(<String>[
-        '/foo/a.dart',
-        '/foo/b.dart',
-        '/foo/c.dart',
-      ]));
-    }, overrides: <Type, Generator>{ FileSystem: () => fs });
-
-    testUsingContext('returns files with spaces and backslashes', () async {
-      await fs.file('a.d').writeAsString(r'snapshot.d: /foo/a\ a.dart /foo/b\\b.dart /foo/c\\ c.dart');
-      expect(await readDepfile('a.d'), unorderedEquals(<String>[
-        r'/foo/a a.dart',
-        r'/foo/b\b.dart',
-        r'/foo/c\ c.dart',
-      ]));
-    }, overrides: <Type, Generator>{ FileSystem: () => fs });
-  });
-
-  group('Snapshotter', () {
-    _FakeGenSnapshot genSnapshot;
-    MemoryFileSystem fs;
-    Snapshotter snapshotter;
-
-    setUp(() {
-      fs = new MemoryFileSystem();
-      genSnapshot = new _FakeGenSnapshot();
-      snapshotter = new Snapshotter();
-    });
-
-    testUsingContext('builds snapshot and checksums when no checksums are present', () async {
-      await fs.file('main.dart').writeAsString('void main() {}');
-      await fs.file('output.snapshot').create();
-      await fs.file('output.snapshot.d').writeAsString('snapshot : main.dart');
-      await snapshotter.buildScriptSnapshot(
-        mainPath: 'main.dart',
-        snapshotPath: 'output.snapshot',
-        depfilePath: 'output.snapshot.d',
-        packagesPath: '.packages',
-      );
-
-      expect(genSnapshot.callCount, 1);
-
-      final Map<String, dynamic> json = JSON.decode(await fs.file('output.snapshot.d.checksums').readAsString());
-      expect(json, hasLength(2));
-      expect(json['main.dart'], '27f5ebf0f8c559b2af9419d190299a5e');
-      expect(json['output.snapshot'], 'd41d8cd98f00b204e9800998ecf8427e');
-    }, overrides: <Type, Generator>{
-      FileSystem: () => fs,
-      GenSnapshot: () => genSnapshot,
-    });
-
-    testUsingContext('builds snapshot and checksums when checksums differ', () async {
-      await fs.file('main.dart').writeAsString('void main() {}');
-      await fs.file('output.snapshot').create();
-      await fs.file('output.snapshot.d').writeAsString('output.snapshot : main.dart');
-      await fs.file('output.snapshot.d.checksums').writeAsString(JSON.encode(<String, dynamic>{
-        'main.dart': '27f5ebf0f8c559b2af9419d190299a5e',
-        'output.snapshot': 'deadbeef01234567890abcdef0123456',
-      }));
-      await snapshotter.buildScriptSnapshot(
-        mainPath: 'main.dart',
-        snapshotPath: 'output.snapshot',
-        depfilePath: 'output.snapshot.d',
-        packagesPath: '.packages',
-      );
-
-      expect(genSnapshot.callCount, 1);
-
-      final Map<String, dynamic> json = JSON.decode(await fs.file('output.snapshot.d.checksums').readAsString());
-      expect(json, hasLength(2));
-      expect(json['main.dart'], '27f5ebf0f8c559b2af9419d190299a5e');
-      expect(json['output.snapshot'], 'd41d8cd98f00b204e9800998ecf8427e');
-    }, overrides: <Type, Generator>{
-      FileSystem: () => fs,
-      GenSnapshot: () => genSnapshot,
-    });
-
-    testUsingContext('builds snapshot and checksums when checksums match but previous snapshot not present', () async {
-      await fs.file('main.dart').writeAsString('void main() {}');
-      await fs.file('output.snapshot.d').writeAsString('output.snapshot : main.dart');
-      await fs.file('output.snapshot.d.checksums').writeAsString(JSON.encode(<String, dynamic>{
-        'main.dart': '27f5ebf0f8c559b2af9419d190299a5e',
-        'output.snapshot': 'd41d8cd98f00b204e9800998ecf8427e',
-      }));
-      await snapshotter.buildScriptSnapshot(
-        mainPath: 'main.dart',
-        snapshotPath: 'output.snapshot',
-        depfilePath: 'output.snapshot.d',
-        packagesPath: '.packages',
-      );
-
-      expect(genSnapshot.callCount, 1);
-
-      final Map<String, dynamic> json = JSON.decode(await fs.file('output.snapshot.d.checksums').readAsString());
-      expect(json, hasLength(2));
-      expect(json['main.dart'], '27f5ebf0f8c559b2af9419d190299a5e');
-      expect(json['output.snapshot'], 'd41d8cd98f00b204e9800998ecf8427e');
-    }, overrides: <Type, Generator>{
-      FileSystem: () => fs,
-      GenSnapshot: () => genSnapshot,
-    });
-
-    testUsingContext('builds snapshot and checksums when main entry point changes', () async {
-      final _FakeGenSnapshot genSnapshot = new _FakeGenSnapshot(
-        snapshotPath: 'output.snapshot',
-        depfilePath: 'output.snapshot.d',
-        depfileContent: 'output.snapshot : other.dart',
-      );
-      context.setVariable(GenSnapshot, genSnapshot);
-
-      await fs.file('main.dart').writeAsString('void main() {}');
-      await fs.file('other.dart').writeAsString('void main() { print("Kanpai ima kimi wa jinsei no ookina ookina butai ni tachi"); }');
-      await fs.file('output.snapshot.d').writeAsString('output.snapshot : main.dart');
-      await fs.file('output.snapshot.d.checksums').writeAsString(JSON.encode(<String, dynamic>{
-        'main.dart': '27f5ebf0f8c559b2af9419d190299a5e',
-        'output.snapshot': 'd41d8cd98f00b204e9800998ecf8427e',
-      }));
-      await snapshotter.buildScriptSnapshot(
-        mainPath: 'other.dart',
-        snapshotPath: 'output.snapshot',
-        depfilePath: 'output.snapshot.d',
-        packagesPath: '.packages',
-      );
-
-      expect(genSnapshot.callCount, 1);
-      final Map<String, dynamic> json = JSON.decode(await fs.file('output.snapshot.d.checksums').readAsString());
-      expect(json, hasLength(2));
-      expect(json['other.dart'], '3238d0ae341339b1731d3c2e195ad177');
-      expect(json['output.snapshot'], 'd41d8cd98f00b204e9800998ecf8427e');
-    }, overrides: <Type, Generator>{
-      FileSystem: () => fs,
-    });
-
-    testUsingContext('skips snapshot when checksums match and previous snapshot is present', () async {
-      await fs.file('main.dart').writeAsString('void main() {}');
-      await fs.file('output.snapshot').create();
-      await fs.file('output.snapshot.d').writeAsString('output.snapshot : main.dart');
-      await fs.file('output.snapshot.d.checksums').writeAsString(JSON.encode(<String, dynamic>{
-        'main.dart': '27f5ebf0f8c559b2af9419d190299a5e',
-        'output.snapshot': 'd41d8cd98f00b204e9800998ecf8427e',
-      }));
-      await snapshotter.buildScriptSnapshot(
-        mainPath: 'main.dart',
-        snapshotPath: 'output.snapshot',
-        depfilePath: 'output.snapshot.d',
-        packagesPath: '.packages',
-      );
-
-      expect(genSnapshot.callCount, 0);
-
-      final Map<String, dynamic> json = JSON.decode(await fs.file('output.snapshot.d.checksums').readAsString());
-      expect(json, hasLength(2));
-      expect(json['main.dart'], '27f5ebf0f8c559b2af9419d190299a5e');
-      expect(json['output.snapshot'], 'd41d8cd98f00b204e9800998ecf8427e');
-    }, overrides: <Type, Generator>{
-      FileSystem: () => fs,
-      GenSnapshot: () => genSnapshot,
-    });
-  });
 }