diff --git a/packages/flutter_tools/lib/src/build_runner/devfs_web.dart b/packages/flutter_tools/lib/src/build_runner/devfs_web.dart
index 90e982631d..2bb3f7ebb0 100644
--- a/packages/flutter_tools/lib/src/build_runner/devfs_web.dart
+++ b/packages/flutter_tools/lib/src/build_runner/devfs_web.dart
@@ -7,7 +7,7 @@ import 'dart:typed_data';
 
 import 'package:dwds/data/build_result.dart';
 import 'package:dwds/dwds.dart';
-import 'package:logging/logging.dart';
+import 'package:logging/logging.dart' as logging;
 import 'package:meta/meta.dart';
 import 'package:mime/mime.dart' as mime;
 import 'package:package_config/package_config.dart';
@@ -19,6 +19,7 @@ import '../asset.dart';
 import '../base/common.dart';
 import '../base/file_system.dart';
 import '../base/io.dart';
+import '../base/logger.dart';
 import '../base/net.dart';
 import '../base/platform.dart';
 import '../base/utils.dart';
@@ -45,7 +46,7 @@ typedef DwdsLauncher = Future<Dwds> Function({
   bool useSseForDebugProxy,
   bool useSseForDebugBackend,
   bool serveDevTools,
-  void Function(Level, String) logWriter,
+  void Function(logging.Level, String) logWriter,
   bool verbose,
   UrlEncoder urlEncoder,
   bool useFileProvider,
@@ -227,6 +228,21 @@ class WebAssetServer implements AssetReader {
         }
         return null;
       }
+      // Ensure dwds is present and provide middleware to avoid trying to
+      // load the through the isolate APIs.
+      final Directory directory = await _loadDwdsDirectory(globals.fs, globals.logger);
+      final shelf.Middleware middleware = (FutureOr<shelf.Response> Function(shelf.Request) innerHandler) {
+        return (shelf.Request request) async {
+          if (request.url.path.endsWith('dwds/src/injected/client.js')) {
+            final Uri uri = directory.uri.resolve('src/injected/client.js');
+            final String result = await globals.fs.file(uri.toFilePath()).readAsString();
+            return shelf.Response.ok(result, headers: <String, String>{
+              HttpHeaders.contentTypeHeader: 'application/javascript'
+            });
+          }
+          return innerHandler(request);
+        };
+      };
 
       // In debug builds, spin up DWDS and the full asset server.
       final Dwds dwds = await dwdsLauncher(
@@ -243,7 +259,7 @@ class WebAssetServer implements AssetReader {
         useSseForDebugProxy: useSseForDebugProxy,
         useSseForDebugBackend: useSseForDebugBackend,
         serveDevTools: false,
-        logWriter: (Level logLevel, String message) => globals.printTrace(message),
+        logWriter: (logging.Level logLevel, String message) => globals.printTrace(message),
         loadStrategy: RequireStrategy(
           ReloadConfiguration.none,
           '.lib.js',
@@ -258,6 +274,7 @@ class WebAssetServer implements AssetReader {
       );
       shelf.Pipeline pipeline = const shelf.Pipeline();
       if (enableDwds) {
+        pipeline = pipeline.addMiddleware(middleware);
         pipeline = pipeline.addMiddleware(dwds.middleware);
       }
       final shelf.Handler dwdsHandler = pipeline.addHandler(server.handleRequest);
@@ -946,3 +963,14 @@ class ReleaseAssetServer {
     return shelf.Response.notFound('');
   }
 }
+
+Future<Directory> _loadDwdsDirectory(FileSystem fileSystem, Logger logger) async {
+  final String toolPackagePath = fileSystem.path.join(
+      Cache.flutterRoot, 'packages', 'flutter_tools');
+  final String packageFilePath = fileSystem.path.join(toolPackagePath, kPackagesFileName);
+  final PackageConfig packageConfig = await loadPackageConfigWithLogging(
+    fileSystem.file(packageFilePath),
+    logger: logger,
+  );
+  return fileSystem.directory(packageConfig['dwds'].packageUriRoot);
+}
diff --git a/packages/flutter_tools/lib/src/build_runner/resident_web_runner.dart b/packages/flutter_tools/lib/src/build_runner/resident_web_runner.dart
index 88f3690bf7..89a8b57d37 100644
--- a/packages/flutter_tools/lib/src/build_runner/resident_web_runner.dart
+++ b/packages/flutter_tools/lib/src/build_runner/resident_web_runner.dart
@@ -22,9 +22,7 @@ import '../base/terminal.dart';
 import '../base/utils.dart';
 import '../build_info.dart';
 import '../build_system/targets/web.dart';
-import '../cache.dart';
 import '../dart/language_version.dart';
-import '../dart/pub.dart';
 import '../devfs.dart';
 import '../device.dart';
 import '../features.dart';
@@ -444,15 +442,6 @@ class _ResidentWebRunner extends ResidentWebRunner {
 
     try {
       return await asyncGuard(() async {
-        // Ensure dwds resources are cached. If the .packages file is missing then
-        // the client.js script cannot be located by the injected handler in dwds.
-        // This will result in a NoSuchMethodError thrown by injected_handler.darts
-        await pub.get(
-          context: PubContext.pubGet,
-          directory: globals.fs.path.join(Cache.flutterRoot, 'packages', 'flutter_tools'),
-          generateSyntheticPackage: false,
-        );
-
         final ExpressionCompiler expressionCompiler =
           debuggingOptions.webEnableExpressionEvaluation
               ? WebExpressionCompiler(device.generator)
diff --git a/packages/flutter_tools/lib/src/cache.dart b/packages/flutter_tools/lib/src/cache.dart
index 898c601fe2..b752f047e4 100644
--- a/packages/flutter_tools/lib/src/cache.dart
+++ b/packages/flutter_tools/lib/src/cache.dart
@@ -4,6 +4,7 @@
 
 import 'package:archive/archive.dart';
 import 'package:meta/meta.dart';
+import 'package:package_config/package_config.dart';
 
 import 'android/gradle_utils.dart';
 import 'base/common.dart';
@@ -14,8 +15,11 @@ import 'base/net.dart';
 import 'base/os.dart' show OperatingSystemUtils;
 import 'base/platform.dart';
 import 'base/process.dart';
+import 'dart/package_map.dart';
+import 'dart/pub.dart';
 import 'features.dart';
 import 'globals.dart' as globals;
+import 'runner/flutter_command.dart';
 
 /// A tag for a set of development artifacts that need to be cached.
 class DevelopmentArtifact {
@@ -126,6 +130,14 @@ class Cache {
         _artifacts.add(IosUsbArtifacts(artifactName, this));
       }
       _artifacts.add(FontSubsetArtifacts(this));
+      _artifacts.add(PubDependencies(
+        fileSystem: _fileSystem,
+        logger: _logger,
+        // flutter root and pub must be lazily initialized to avoid accessing
+        // before the version is determined.
+        flutterRoot: () => flutterRoot,
+        pub: () => pub,
+      ));
     } else {
       _artifacts.addAll(artifacts);
     }
@@ -432,7 +444,14 @@ class Cache {
     );
   }
 
-  bool isUpToDate() => _artifacts.every((ArtifactSet artifact) => artifact.isUpToDate());
+  Future<bool> isUpToDate() async {
+    for (final ArtifactSet artifact in _artifacts) {
+      if (!await artifact.isUpToDate()) {
+        return false;
+      }
+    }
+    return true;
+  }
 
   /// Update the cache to contain all `requiredArtifacts`.
   Future<void> updateAll(Set<DevelopmentArtifact> requiredArtifacts) async {
@@ -444,7 +463,7 @@ class Cache {
         _logger.printTrace('Artifact $artifact is not required, skipping update.');
         continue;
       }
-      if (artifact.isUpToDate()) {
+      if (await artifact.isUpToDate()) {
         continue;
       }
       try {
@@ -502,7 +521,7 @@ abstract class ArtifactSet {
   final DevelopmentArtifact developmentArtifact;
 
   /// [true] if the artifact is up to date.
-  bool isUpToDate();
+  Future<bool> isUpToDate();
 
   /// The environment variables (if any) required to consume the artifacts.
   Map<String, String> get environment {
@@ -546,7 +565,7 @@ abstract class CachedArtifact extends ArtifactSet {
   }
 
   @override
-  bool isUpToDate() {
+  Future<bool> isUpToDate() async {
     if (!location.existsSync()) {
       return false;
     }
@@ -592,6 +611,66 @@ abstract class CachedArtifact extends ArtifactSet {
   Uri _toStorageUri(String path) => Uri.parse('${cache.storageBaseUrl}/$path');
 }
 
+/// Ensures that the source files for all of the dependencies for the
+/// flutter_tool are present.
+///
+/// This does not handle cases wheere the source files are modified or the
+/// directory contents are incomplete.
+class PubDependencies extends ArtifactSet {
+  PubDependencies({
+    // Needs to be lazy to avoid reading from the cache before the root is initialized.
+    @required String Function() flutterRoot,
+    @required FileSystem fileSystem,
+    @required Logger logger,
+    @required Pub Function() pub,
+  }) : _logger = logger,
+       _fileSystem = fileSystem,
+       _flutterRoot = flutterRoot,
+       _pub = pub,
+       super(DevelopmentArtifact.universal);
+
+  final String Function() _flutterRoot;
+  final FileSystem _fileSystem;
+  final Logger _logger;
+  final Pub Function() _pub;
+
+  @override
+  Future<bool> isUpToDate() async {
+    final File toolPackageConfig = _fileSystem.file(
+      _fileSystem.path.join(_flutterRoot(), 'packages', 'flutter_tools', kPackagesFileName),
+    );
+    if (!toolPackageConfig.existsSync()) {
+      return false;
+    }
+    final PackageConfig packageConfig = await loadPackageConfigWithLogging(
+      toolPackageConfig,
+      logger: _logger,
+      throwOnError: false,
+    );
+    if (packageConfig == null || packageConfig == PackageConfig.empty ) {
+      return false;
+    }
+    for (final Package package in packageConfig.packages) {
+      if (!_fileSystem.directory(package.packageUriRoot).existsSync()) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  @override
+  String get name => 'pub_dependencies';
+
+  @override
+  Future<void> update(ArtifactUpdater artifactUpdater) async {
+    await _pub().get(
+      context: PubContext.pubGet,
+      directory: _fileSystem.path.join(_flutterRoot(), 'packages', 'flutter_tools'),
+      generateSyntheticPackage: false,
+    );
+  }
+}
+
 /// A cached artifact containing fonts used for Material Design.
 class MaterialFonts extends CachedArtifact {
   MaterialFonts(Cache cache) : super(
@@ -979,7 +1058,7 @@ class AndroidMavenArtifacts extends ArtifactSet {
   }
 
   @override
-  bool isUpToDate() {
+  Future<bool> isUpToDate() async {
     // The dependencies are downloaded and cached by Gradle.
     // The tool doesn't know if the dependencies are already cached at this point.
     // Therefore, call Gradle to figure this out.
diff --git a/packages/flutter_tools/lib/src/commands/precache.dart b/packages/flutter_tools/lib/src/commands/precache.dart
index d21c814939..78a5c911e4 100644
--- a/packages/flutter_tools/lib/src/commands/precache.dart
+++ b/packages/flutter_tools/lib/src/commands/precache.dart
@@ -156,7 +156,7 @@ class PrecacheCommand extends FlutterCommand {
         requiredArtifacts.add(artifact);
       }
     }
-    if (!_cache.isUpToDate()) {
+    if (!await _cache.isUpToDate()) {
       await _cache.updateAll(requiredArtifacts);
     } else {
       _logger.printStatus('Already up-to-date.');
diff --git a/packages/flutter_tools/lib/src/context_runner.dart b/packages/flutter_tools/lib/src/context_runner.dart
index a8eb4ff903..4bd5da0d64 100644
--- a/packages/flutter_tools/lib/src/context_runner.dart
+++ b/packages/flutter_tools/lib/src/context_runner.dart
@@ -232,7 +232,8 @@ Future<T> runInContext<T>(
         botDetector: globals.botDetector,
         platform: globals.platform,
         usage: globals.flutterUsage,
-        toolStampFile: globals.cache.getStampFileFor('flutter_tools'),
+        // Avoid a circular dependency by making this access lazy.
+        toolStampFile: () => globals.cache.getStampFileFor('flutter_tools'),
       ),
       ShutdownHooks: () => ShutdownHooks(logger: globals.logger),
       Stdio: () => Stdio(),
diff --git a/packages/flutter_tools/lib/src/dart/pub.dart b/packages/flutter_tools/lib/src/dart/pub.dart
index ce7d328b80..9bff641361 100644
--- a/packages/flutter_tools/lib/src/dart/pub.dart
+++ b/packages/flutter_tools/lib/src/dart/pub.dart
@@ -80,7 +80,7 @@ abstract class Pub {
     @required Platform platform,
     @required BotDetector botDetector,
     @required Usage usage,
-    File toolStampFile,
+    File Function() toolStampFile,
   }) = _DefaultPub;
 
   /// Runs `pub get`.
@@ -141,7 +141,7 @@ class _DefaultPub implements Pub {
     @required Platform platform,
     @required BotDetector botDetector,
     @required Usage usage,
-    File toolStampFile,
+   File Function() toolStampFile,
   }) : _toolStampFile = toolStampFile,
        _fileSystem = fileSystem,
        _logger = logger,
@@ -159,7 +159,7 @@ class _DefaultPub implements Pub {
   final Platform _platform;
   final BotDetector _botDetector;
   final Usage _usage;
-  final File _toolStampFile;
+  final File Function() _toolStampFile;
 
   @override
   Future<void> get({
@@ -399,10 +399,10 @@ class _DefaultPub implements Pub {
     if (pubSpecYaml.lastModifiedSync().isAfter(dotPackagesLastModified)) {
       return true;
     }
-
-    if (_toolStampFile != null &&
-        _toolStampFile.existsSync() &&
-        _toolStampFile.lastModifiedSync().isAfter(dotPackagesLastModified)) {
+    final File toolStampFile = _toolStampFile != null ? _toolStampFile() : null;
+    if (toolStampFile != null &&
+        toolStampFile.existsSync() &&
+        toolStampFile.lastModifiedSync().isAfter(dotPackagesLastModified)) {
       return true;
     }
     return false;
diff --git a/packages/flutter_tools/lib/src/template.dart b/packages/flutter_tools/lib/src/template.dart
index 094321b417..dcbc6ff728 100644
--- a/packages/flutter_tools/lib/src/template.dart
+++ b/packages/flutter_tools/lib/src/template.dart
@@ -291,36 +291,13 @@ Future<Directory> _templateImageDirectory(String name, FileSystem fileSystem, Lo
   final String toolPackagePath = fileSystem.path.join(
       Cache.flutterRoot, 'packages', 'flutter_tools');
   final String packageFilePath = fileSystem.path.join(toolPackagePath, kPackagesFileName);
-  // Ensure that .packgaes is present.
-  if (!fileSystem.file(packageFilePath).existsSync()) {
-    await _ensurePackageDependencies(toolPackagePath, pub);
-  }
-  PackageConfig packageConfig = await loadPackageConfigWithLogging(
+  final PackageConfig packageConfig = await loadPackageConfigWithLogging(
     fileSystem.file(packageFilePath),
     logger: logger,
   );
-  Uri imagePackageLibDir = packageConfig['flutter_template_images']?.packageUriRoot;
-  // Ensure that the template image package is present.
-  if (imagePackageLibDir == null || !fileSystem.directory(imagePackageLibDir).existsSync()) {
-    await _ensurePackageDependencies(toolPackagePath, pub);
-    packageConfig = await loadPackageConfigWithLogging(
-      fileSystem.file(packageFilePath),
-      logger: logger,
-    );
-    imagePackageLibDir = packageConfig['flutter_template_images']?.packageUriRoot;
-  }
+  final Uri imagePackageLibDir = packageConfig['flutter_template_images']?.packageUriRoot;
   return fileSystem.directory(imagePackageLibDir)
       .parent
       .childDirectory('templates')
       .childDirectory(name);
 }
-
-// Runs 'pub get' for the given path to ensure that .packages is created and
-// all dependencies are present.
-Future<void> _ensurePackageDependencies(String packagePath, Pub pub) async {
-  await pub.get(
-    context: PubContext.pubGet,
-    directory: packagePath,
-    generateSyntheticPackage: false,
-  );
-}
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/analyze_continuously_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/analyze_continuously_test.dart
index 06dd6aeb71..badc6932cb 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/analyze_continuously_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/analyze_continuously_test.dart
@@ -117,7 +117,7 @@ void main() {
       platform: const LocalPlatform(),
       usage: globals.flutterUsage,
       botDetector: globals.botDetector,
-      toolStampFile: globals.fs.file('test'),
+      toolStampFile: () => globals.fs.file('test'),
     );
     await pub.get(
       context: PubContext.flutterTests,
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/precache_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/precache_test.dart
index b4dcd818fe..9b79ff0724 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/precache_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/precache_test.dart
@@ -23,7 +23,7 @@ void main() {
     // Release lock between test cases.
     Cache.releaseLock();
 
-    when(cache.isUpToDate()).thenReturn(false);
+    when(cache.isUpToDate()).thenAnswer((Invocation _) => Future<bool>.value(false));
     when(cache.updateAll(any)).thenAnswer((Invocation invocation) {
       artifacts = invocation.positionalArguments.first as Set<DevelopmentArtifact>;
       return Future<void>.value(null);
@@ -410,7 +410,7 @@ void main() {
   });
 
   testUsingContext('precache deletes artifact stampfiles when --force is provided', () async {
-    when(cache.isUpToDate()).thenReturn(true);
+    when(cache.isUpToDate()).thenAnswer((Invocation _) => Future<bool>.value(true));
     final PrecacheCommand command = PrecacheCommand(
       cache: cache,
       logger: BufferLogger.test(),
diff --git a/packages/flutter_tools/test/general.shard/cache_test.dart b/packages/flutter_tools/test/general.shard/cache_test.dart
index 111bdc4cb2..427f14c16e 100644
--- a/packages/flutter_tools/test/general.shard/cache_test.dart
+++ b/packages/flutter_tools/test/general.shard/cache_test.dart
@@ -13,6 +13,7 @@ import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/base/os.dart';
 import 'package:flutter_tools/src/base/platform.dart';
 import 'package:flutter_tools/src/cache.dart';
+import 'package:flutter_tools/src/dart/pub.dart';
 import 'package:flutter_tools/src/globals.dart' as globals;
 import 'package:meta/meta.dart';
 import 'package:mockito/mockito.dart';
@@ -137,25 +138,25 @@ void main() {
       ProcessManager: () => FakeProcessManager.any(),
     });
 
-    testUsingContext('should not be up to date, if some cached artifact is not', () {
+    testUsingContext('should not be up to date, if some cached artifact is not', () async {
       final CachedArtifact artifact1 = MockCachedArtifact();
       final CachedArtifact artifact2 = MockCachedArtifact();
-      when(artifact1.isUpToDate()).thenReturn(true);
-      when(artifact2.isUpToDate()).thenReturn(false);
+      when(artifact1.isUpToDate()).thenAnswer((Invocation _) => Future<bool>.value(true));
+      when(artifact2.isUpToDate()).thenAnswer((Invocation _) => Future<bool>.value(false));
       final Cache cache = Cache(artifacts: <CachedArtifact>[artifact1, artifact2]);
-      expect(cache.isUpToDate(), isFalse);
+      expect(await cache.isUpToDate(), isFalse);
     }, overrides: <Type, Generator>{
       ProcessManager: () => FakeProcessManager.any(),
       FileSystem: () => MemoryFileSystem.test(),
     });
 
-    testUsingContext('should be up to date, if all cached artifacts are', () {
+    testUsingContext('should be up to date, if all cached artifacts are', () async {
       final CachedArtifact artifact1 = MockCachedArtifact();
       final CachedArtifact artifact2 = MockCachedArtifact();
-      when(artifact1.isUpToDate()).thenReturn(true);
-      when(artifact2.isUpToDate()).thenReturn(true);
+      when(artifact1.isUpToDate()).thenAnswer((Invocation _) => Future<bool>.value(true));
+      when(artifact2.isUpToDate()).thenAnswer((Invocation _) => Future<bool>.value(true));
       final Cache cache = Cache(artifacts: <CachedArtifact>[artifact1, artifact2]);
-      expect(cache.isUpToDate(), isTrue);
+      expect(await cache.isUpToDate(), isTrue);
     }, overrides: <Type, Generator>{
       ProcessManager: () => FakeProcessManager.any(),
       FileSystem: () => MemoryFileSystem.test(),
@@ -164,8 +165,8 @@ void main() {
     testUsingContext('should update cached artifacts which are not up to date', () async {
       final CachedArtifact artifact1 = MockCachedArtifact();
       final CachedArtifact artifact2 = MockCachedArtifact();
-      when(artifact1.isUpToDate()).thenReturn(true);
-      when(artifact2.isUpToDate()).thenReturn(false);
+      when(artifact1.isUpToDate()).thenAnswer((Invocation _) => Future<bool>.value(true));
+      when(artifact2.isUpToDate()).thenAnswer((Invocation _) => Future<bool>.value(false));
       final Cache cache = Cache(artifacts: <CachedArtifact>[artifact1, artifact2]);
       await cache.updateAll(<DevelopmentArtifact>{
         null,
@@ -206,8 +207,8 @@ void main() {
     testUsingContext('failed storage.googleapis.com download shows China warning', () async {
       final CachedArtifact artifact1 = MockCachedArtifact();
       final CachedArtifact artifact2 = MockCachedArtifact();
-      when(artifact1.isUpToDate()).thenReturn(false);
-      when(artifact2.isUpToDate()).thenReturn(false);
+      when(artifact1.isUpToDate()).thenAnswer((Invocation _) => Future<bool>.value(false));
+      when(artifact2.isUpToDate()).thenAnswer((Invocation _) => Future<bool>.value(false));
       final MockInternetAddress address = MockInternetAddress();
       when(address.host).thenReturn('storage.googleapis.com');
       when(artifact1.update(any)).thenThrow(SocketException(
@@ -317,7 +318,7 @@ void main() {
         ..createSync(recursive: true);
       when(mockCache.getRoot()).thenReturn(cacheRoot);
       final AndroidMavenArtifacts mavenArtifacts = AndroidMavenArtifacts(mockCache);
-      expect(mavenArtifacts.isUpToDate(), isFalse);
+      expect(await mavenArtifacts.isUpToDate(), isFalse);
 
       final Directory gradleWrapperDir = globals.fs.systemTempDirectory.createTempSync('flutter_cache_test_gradle_wrapper.');
       when(mockCache.getArtifactDirectory('gradle_wrapper')).thenReturn(gradleWrapperDir);
@@ -340,7 +341,7 @@ void main() {
 
       await mavenArtifacts.update(MockArtifactUpdater());
 
-      expect(mavenArtifacts.isUpToDate(), isFalse);
+      expect(await mavenArtifacts.isUpToDate(), isFalse);
     }, overrides: <Type, Generator>{
       Cache: () => mockCache,
       FileSystem: () => memoryFileSystem,
@@ -660,6 +661,69 @@ void main() {
 
     expect(cache.getStampFor('foo'), 'ABC');
   });
+
+  testWithoutContext('PubDependencies needs to be updated if the package config'
+    ' file or the source directories are missing', () async {
+    final BufferLogger logger = BufferLogger.test();
+    final MemoryFileSystem fileSystem = MemoryFileSystem.test();
+    final PubDependencies pubDependencies = PubDependencies(
+      flutterRoot: () => '',
+      fileSystem: fileSystem,
+      logger: logger,
+      pub: () => MockPub(),
+    );
+
+    expect(await pubDependencies.isUpToDate(), false); // no package config
+
+    fileSystem.file('packages/flutter_tools/.packages')
+      ..createSync(recursive: true)
+      ..writeAsStringSync('\n');
+    fileSystem.file('packages/flutter_tools/.dart_tool/package_config.json')
+      ..createSync(recursive: true)
+      ..writeAsStringSync('''
+{
+  "configVersion": 2,
+  "packages": [
+    {
+      "name": "example",
+      "rootUri": "file:///.pub-cache/hosted/pub.dartlang.org/example-7.0.0",
+      "packageUri": "lib/",
+      "languageVersion": "2.7"
+    }
+  ],
+  "generated": "2020-09-15T20:29:20.691147Z",
+  "generator": "pub",
+  "generatorVersion": "2.10.0-121.0.dev"
+}
+''');
+
+    expect(await pubDependencies.isUpToDate(), false); // dependencies are missing.
+
+    fileSystem.file('.pub-cache/hosted/pub.dartlang.org/example-7.0.0/lib/foo.dart')
+      .createSync(recursive: true);
+
+    expect(await pubDependencies.isUpToDate(), true);
+  });
+
+  testWithoutContext('PubDependencies updates via pub get', () async {
+    final BufferLogger logger = BufferLogger.test();
+    final MemoryFileSystem fileSystem = MemoryFileSystem.test();
+    final MockPub pub = MockPub();
+    final PubDependencies pubDependencies = PubDependencies(
+      flutterRoot: () => '',
+      fileSystem: fileSystem,
+      logger: logger,
+      pub: () => pub,
+    );
+
+    await pubDependencies.update(MockArtifactUpdater());
+
+    verify(pub.get(
+      context: PubContext.pubGet,
+      directory: 'packages/flutter_tools',
+      generateSyntheticPackage: false,
+    )).called(1);
+  });
 }
 
 class FakeCachedArtifact extends EngineCachedArtifact {
@@ -724,6 +788,7 @@ class MockInternetAddress extends Mock implements InternetAddress {}
 class MockCache extends Mock implements Cache {}
 class MockOperatingSystemUtils extends Mock implements OperatingSystemUtils {}
 class MockVersionedPackageResolver extends Mock implements VersionedPackageResolver {}
+class MockPub extends Mock implements Pub {}
 class FakeCache extends Cache {
   FakeCache({
     @required Logger logger,
diff --git a/packages/flutter_tools/test/general.shard/resident_web_runner_test.dart b/packages/flutter_tools/test/general.shard/resident_web_runner_test.dart
index 78494a4183..b902c7c205 100644
--- a/packages/flutter_tools/test/general.shard/resident_web_runner_test.dart
+++ b/packages/flutter_tools/test/general.shard/resident_web_runner_test.dart
@@ -294,12 +294,6 @@ void main() {
 
     verify(mockAppConnection.runMain()).called(1);
     verify(status.stop()).called(1);
-    verify(pub.get(
-      context: PubContext.pubGet,
-      directory: anyNamed('directory'),
-      generateSyntheticPackage: false,
-    )).called(1);
-
     expect(bufferLogger.statusText, contains('Debug service listening on ws://127.0.0.1/abcd/'));
     expect(debugConnectionInfo.wsUri.toString(), 'ws://127.0.0.1/abcd/');
   }, overrides: <Type, Generator>{
diff --git a/packages/flutter_tools/test/src/testbed.dart b/packages/flutter_tools/test/src/testbed.dart
index 0914900a23..4a4e2a9bfe 100644
--- a/packages/flutter_tools/test/src/testbed.dart
+++ b/packages/flutter_tools/test/src/testbed.dart
@@ -931,7 +931,7 @@ class FakeCache implements Cache {
   }
 
   @override
-  bool isUpToDate() {
+  Future<bool> isUpToDate() async {
     return true;
   }