refactor context to be implicit-downcast safe (#31622)

packages/flutter_tools/analysis_options.yaml

@@ -3,6 +3,12 @@
 
 include: ../../analysis_options.yaml
 
+analyzer:
+  strong-mode:
+    implicit-casts: true
+    implicit-dynamic: false
+
 linter:
   rules:
-    - unawaited_futures
+    unawaited_futures: true
+    avoid_as: false # Disabled so we can gradually migrate to no implicit dynamic.

packages/flutter_tools/lib/src/android/android_sdk.dart

@@ -17,7 +17,7 @@ import '../convert.dart';
 import '../globals.dart';
 import 'android_studio.dart' as android_studio;
 
-AndroidSdk get androidSdk => context[AndroidSdk];
+AndroidSdk get androidSdk => context.get<AndroidSdk>();
 
 const String kAndroidHome = 'ANDROID_HOME';
 const String kAndroidSdkRoot = 'ANDROID_SDK_ROOT';

packages/flutter_tools/lib/src/android/android_studio.dart

@@ -13,7 +13,7 @@ import '../globals.dart';
 import '../ios/ios_workflow.dart';
 import '../ios/plist_utils.dart' as plist;
 
-AndroidStudio get androidStudio => context[AndroidStudio];
+AndroidStudio get androidStudio => context.get<AndroidStudio>();
 
 // Android Studio layout:
 

packages/flutter_tools/lib/src/android/android_workflow.dart

@@ -21,9 +21,9 @@ import 'android_sdk.dart';
 const int kAndroidSdkMinVersion = 28;
 final Version kAndroidSdkBuildToolsMinVersion = Version(28, 0, 3);
 
-AndroidWorkflow get androidWorkflow => context[AndroidWorkflow];
-AndroidValidator get androidValidator => context[AndroidValidator];
-AndroidLicenseValidator get androidLicenseValidator => context[AndroidLicenseValidator];
+AndroidWorkflow get androidWorkflow => context.get<AndroidWorkflow>();
+AndroidValidator get androidValidator => context.get<AndroidValidator>();
+AndroidLicenseValidator get androidLicenseValidator => context.get<AndroidLicenseValidator>();
 
 enum LicensesAccepted {
   none,

packages/flutter_tools/lib/src/application_package.dart

@@ -28,7 +28,7 @@ import 'web/web_device.dart';
 import 'windows/application_package.dart';
 
 class ApplicationPackageFactory {
-  static ApplicationPackageFactory get instance => context[ApplicationPackageFactory];
+  static ApplicationPackageFactory get instance => context.get<ApplicationPackageFactory>();
 
   Future<ApplicationPackage> getPackageForPlatform(
     TargetPlatform platform, {

packages/flutter_tools/lib/src/artifacts.dart

@@ -100,7 +100,7 @@ class EngineBuildPaths {
 
 // Manages the engine artifacts of Flutter.
 abstract class Artifacts {
-  static Artifacts get instance => context[Artifacts];
+  static Artifacts get instance => context.get<Artifacts>();
 
   static LocalEngineArtifacts getLocalEngine(String engineSrcPath, EngineBuildPaths engineBuildPaths) {
     return LocalEngineArtifacts(engineSrcPath, engineBuildPaths.targetEngine, engineBuildPaths.hostEngine);

packages/flutter_tools/lib/src/asset.dart

@@ -23,7 +23,7 @@ const AssetBundleFactory _kManifestFactory = _ManifestAssetBundleFactory();
 /// Injected factory class for spawning [AssetBundle] instances.
 abstract class AssetBundleFactory {
   /// The singleton instance, pulled from the [AppContext].
-  static AssetBundleFactory get instance => context[AssetBundleFactory];
+  static AssetBundleFactory get instance => context.get<AssetBundleFactory>();
 
   static AssetBundleFactory get defaultInstance => _kManifestFactory;
 

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

@@ -21,7 +21,7 @@ import 'file_system.dart';
 import 'fingerprint.dart';
 import 'process.dart';
 
-GenSnapshot get genSnapshot => context[GenSnapshot];
+GenSnapshot get genSnapshot => context.get<GenSnapshot>();
 
 /// A snapshot build configuration.
 class SnapshotType {

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

@@ -14,7 +14,7 @@ class Config {
       _values = json.decode(_configFile.readAsStringSync());
   }
 
-  static Config get instance => context[Config];
+  static Config get instance => context.get<Config>();
 
   File _configFile;
   String get configPath => _configFile.path;

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

@@ -33,7 +33,7 @@ class ContextDependencyCycleException implements Exception {
 /// context will not have any values associated with it.
 ///
 /// This is guaranteed to never return `null`.
-AppContext get context => Zone.current[_Key.key] ?? AppContext._root;
+AppContext get context => Zone.current[_Key.key] as AppContext ?? AppContext._root;
 
 /// A lookup table (mapping types to values) and an implied scope, in which
 /// code is run.
@@ -107,6 +107,17 @@ class AppContext {
 
   /// Gets the value associated with the specified [type], or `null` if no
   /// such value has been associated.
+  T get<T>() {
+    dynamic value = _generateIfNecessary(T, _overrides);
+    if (value == null && _parent != null) {
+      value = _parent.get<T>();
+    }
+    return _unboxNull(value ?? _generateIfNecessary(T, _fallbacks)) as T;
+  }
+
+  /// Gets the value associated with the specified [type], or `null` if no
+  /// such value has been associated.
+  @Deprecated('use get<T> instead for type safety.')
   Object operator [](Type type) {
     dynamic value = _generateIfNecessary(type, _overrides);
     if (value == null && _parent != null)

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

@@ -23,7 +23,7 @@ const FileSystem _kLocalFs = LocalFileSystem();
 ///
 /// By default it uses local disk-based implementation. Override this in tests
 /// with [MemoryFileSystem].
-FileSystem get fs => context[FileSystem] ?? _kLocalFs;
+FileSystem get fs => context.get<FileSystem>() ?? _kLocalFs;
 
 /// Gets a [FileSystem] that will record file system activity to the specified
 /// base recording [location].

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

@@ -8,7 +8,7 @@ import 'context.dart';
 
 /// command-line flags and options that were specified during the invocation of
 /// the Flutter tool.
-Flags get flags => context[Flags];
+Flags get flags => context.get<Flags>();
 
 /// Encapsulation of the command-line flags and options that were specified
 /// during the invocation of the Flutter tool.

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

@@ -163,7 +163,7 @@ class Stdio {
   bool get supportsAnsiEscapes => hasTerminal ? io.stdout.supportsAnsiEscapes : false;
 }
 
-Stdio get stdio => context[Stdio];
+Stdio get stdio => context.get<Stdio>();
 io.IOSink get stdout => stdio.stdout;
 Stream<List<int>> get stdin => stdio.stdin;
 io.IOSink get stderr => stdio.stderr;

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

@@ -19,7 +19,7 @@ const Duration _kSlowOperation = Duration(minutes: 2);
 /// The [TimeoutConfiguration] instance.
 ///
 /// If not provided via injection, a default instance is provided.
-TimeoutConfiguration get timeoutConfiguration => context[TimeoutConfiguration] ?? const TimeoutConfiguration();
+TimeoutConfiguration get timeoutConfiguration => context.get<TimeoutConfiguration>() ?? const TimeoutConfiguration();
 
 class TimeoutConfiguration {
   const TimeoutConfiguration();
@@ -486,7 +486,7 @@ abstract class Status {
   final VoidCallback onFinish;
 
   @protected
-  final Stopwatch _stopwatch = context[Stopwatch] ?? Stopwatch();
+  final Stopwatch _stopwatch = context.get<Stopwatch>() ?? Stopwatch();
 
   @protected
   @visibleForTesting

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

@@ -36,8 +36,8 @@ Future<bool> doesRemoteFileExist(Uri url) async =>
 Future<List<int>> _attempt(Uri url, { bool onlyHeaders = false }) async {
   printTrace('Downloading: $url');
   HttpClient httpClient;
-  if (context[HttpClientFactory] != null) {
-    httpClient = (context[HttpClientFactory] as HttpClientFactory)(); // ignore: avoid_as
+  if (context.get<HttpClientFactory>() != null) {
+    httpClient = context.get<HttpClientFactory>()();
   } else {
     httpClient = HttpClient();
   }

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

@@ -11,7 +11,7 @@ import 'process.dart';
 import 'process_manager.dart';
 
 /// Returns [OperatingSystemUtils] active in the current app context (i.e. zone).
-OperatingSystemUtils get os => context[OperatingSystemUtils];
+OperatingSystemUtils get os => context.get<OperatingSystemUtils>();
 
 abstract class OperatingSystemUtils {
   factory OperatingSystemUtils() {

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

@@ -14,7 +14,7 @@ export 'package:platform/platform.dart';
 const Platform _kLocalPlatform = LocalPlatform();
 const String _kRecordingType = 'platform';
 
-Platform get platform => context[Platform] ?? _kLocalPlatform;
+Platform get platform => context.get<Platform>() ?? _kLocalPlatform;
 
 /// Serializes the current [platform] to the specified base recording
 /// [location].

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

@@ -16,7 +16,7 @@ const String _kRecordingType = 'process';
 const ProcessManager _kLocalProcessManager = LocalProcessManager();
 
 /// The active process manager.
-ProcessManager get processManager => context[ProcessManager] ?? _kLocalProcessManager;
+ProcessManager get processManager => context.get<ProcessManager>() ?? _kLocalProcessManager;
 
 /// Gets a [ProcessManager] that will record process invocation activity to the
 /// specified base recording [location].

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

@@ -14,9 +14,9 @@ import 'utils.dart';
 final AnsiTerminal _kAnsiTerminal = AnsiTerminal();
 
 AnsiTerminal get terminal {
-  return (context == null || context[AnsiTerminal] == null)
+  return (context == null || context.get<AnsiTerminal>() == null)
       ? _kAnsiTerminal
-      : context[AnsiTerminal];
+      : context.get<AnsiTerminal>();
 }
 
 enum TerminalColor {
@@ -31,9 +31,9 @@ enum TerminalColor {
 
 final OutputPreferences _kOutputPreferences = OutputPreferences();
 
-OutputPreferences get outputPreferences => (context == null || context[OutputPreferences] == null)
+OutputPreferences get outputPreferences => (context == null || context.get<OutputPreferences>() == null)
     ? _kOutputPreferences
-    : context[OutputPreferences];
+    : context.get<OutputPreferences>();
 
 /// A class that contains the context settings for command text output to the
 /// console.

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

@@ -5,7 +5,7 @@
 import 'context.dart';
 
 /// The current system clock instance.
-SystemClock get systemClock => context[SystemClock];
+SystemClock get systemClock => context.get<SystemClock>();
 
 /// A class for making time based operations testable.
 class SystemClock {

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

@@ -4,7 +4,7 @@
 
 import 'context.dart';
 
-UserMessages get userMessages => context[UserMessages];
+UserMessages get userMessages => context.get<UserMessages>();
 
 /// Class containing message strings that can be produced by Flutter tools.
 class UserMessages {

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

@@ -49,7 +49,7 @@ class BotDetector {
 }
 
 bool get isRunningOnBot {
-  final BotDetector botDetector = context[BotDetector] ?? _kBotDetector;
+  final BotDetector botDetector = context.get<BotDetector>() ?? _kBotDetector;
   return botDetector.isRunningOnBot;
 }
 

packages/flutter_tools/lib/src/cache.dart

@@ -197,7 +197,7 @@ class Cache {
   }
   String _fuchsiaRevision;
 
-  static Cache get instance => context[Cache];
+  static Cache get instance => context.get<Cache>();
 
   /// Return the top-level directory in the cache; this is `bin/cache`.
   Directory getRoot() {

packages/flutter_tools/lib/src/codegen.dart

@@ -22,7 +22,7 @@ const String kMultiRootScheme = 'org-dartlang-app';
 ///
 /// If [experimentalBuildEnabled] is false, this will contain an unsupported
 /// implementation.
-CodeGenerator get codeGenerator => context[CodeGenerator];
+CodeGenerator get codeGenerator => context.get<CodeGenerator>();
 
 /// A wrapper for a build_runner process which delegates to a generated
 /// build script.

packages/flutter_tools/lib/src/compile.dart

@@ -23,7 +23,7 @@ import 'dart/package_map.dart';
 import 'globals.dart';
 import 'project.dart';
 
-KernelCompilerFactory get kernelCompilerFactory => context[KernelCompilerFactory];
+KernelCompilerFactory get kernelCompilerFactory => context.get<KernelCompilerFactory>();
 
 class KernelCompilerFactory {
   const KernelCompilerFactory();

packages/flutter_tools/lib/src/devfs.dart

@@ -26,7 +26,7 @@ class DevFSConfig {
   bool noDirectorySymlinks = false;
 }
 
-DevFSConfig get devFSConfig => context[DevFSConfig];
+DevFSConfig get devFSConfig => context.get<DevFSConfig>();
 
 /// Common superclass for content copied to the device.
 abstract class DevFSContent {

packages/flutter_tools/lib/src/device.dart

@@ -24,7 +24,7 @@ import 'tester/flutter_tester.dart';
 import 'web/web_device.dart';
 import 'windows/windows_device.dart';
 
-DeviceManager get deviceManager => context[DeviceManager];
+DeviceManager get deviceManager => context.get<DeviceManager>();
 
 /// A class to get all available devices.
 class DeviceManager {

packages/flutter_tools/lib/src/doctor.dart

@@ -33,11 +33,11 @@ import 'version.dart';
 import 'vscode/vscode_validator.dart';
 import 'windows/windows_workflow.dart';
 
-Doctor get doctor => context[Doctor];
+Doctor get doctor => context.get<Doctor>();
 
 abstract class DoctorValidatorsProvider {
   /// The singleton instance, pulled from the [AppContext].
-  static DoctorValidatorsProvider get instance => context[DoctorValidatorsProvider];
+  static DoctorValidatorsProvider get instance => context.get<DoctorValidatorsProvider>();
 
   static final DoctorValidatorsProvider defaultInstance = _DefaultDoctorValidatorsProvider();
 

packages/flutter_tools/lib/src/emulator.dart

@@ -13,7 +13,7 @@ import 'base/process_manager.dart';
 import 'globals.dart';
 import 'ios/ios_emulators.dart';
 
-EmulatorManager get emulatorManager => context[EmulatorManager];
+EmulatorManager get emulatorManager => context.get<EmulatorManager>();
 
 /// A class to get all available emulators.
 class EmulatorManager {

packages/flutter_tools/lib/src/fuchsia/fuchsia_sdk.dart

@@ -13,10 +13,10 @@ import '../convert.dart';
 import '../globals.dart';
 
 /// The [FuchsiaSdk] instance.
-FuchsiaSdk get fuchsiaSdk => context[FuchsiaSdk];
+FuchsiaSdk get fuchsiaSdk => context.get<FuchsiaSdk>();
 
 /// The [FuchsiaArtifacts] instance.
-FuchsiaArtifacts get fuchsiaArtifacts => context[FuchsiaArtifacts];
+FuchsiaArtifacts get fuchsiaArtifacts => context.get<FuchsiaArtifacts>();
 
 /// The Fuchsia SDK shell commands.
 ///

packages/flutter_tools/lib/src/fuchsia/fuchsia_workflow.dart

@@ -8,7 +8,7 @@ import '../doctor.dart';
 import 'fuchsia_sdk.dart';
 
 /// The [FuchsiaWorkflow] instance.
-FuchsiaWorkflow get fuchsiaWorkflow => context[FuchsiaWorkflow];
+FuchsiaWorkflow get fuchsiaWorkflow => context.get<FuchsiaWorkflow>();
 
 /// The Fuchsia-specific implementation of a [Workflow].
 ///

packages/flutter_tools/lib/src/globals.dart

@@ -9,7 +9,7 @@ import 'base/logger.dart';
 import 'base/terminal.dart';
 import 'cache.dart';
 
-Logger get logger => context[Logger];
+Logger get logger => context.get<Logger>();
 Cache get cache => Cache.instance;
 Config get config => Config.instance;
 Artifacts get artifacts => Artifacts.instance;

packages/flutter_tools/lib/src/ios/cocoapods.dart

@@ -37,7 +37,7 @@ const String cocoaPodsUpgradeInstructions = '''
   brew upgrade cocoapods
   pod setup''';
 
-CocoaPods get cocoaPods => context[CocoaPods];
+CocoaPods get cocoaPods => context.get<CocoaPods>();
 
 /// Result of evaluating the CocoaPods installation.
 enum CocoaPodsStatus {

packages/flutter_tools/lib/src/ios/ios_workflow.dart

@@ -15,9 +15,9 @@ import 'cocoapods.dart';
 import 'mac.dart';
 import 'plist_utils.dart' as plist;
 
-IOSWorkflow get iosWorkflow => context[IOSWorkflow];
-IOSValidator get iosValidator => context[IOSValidator];
-CocoaPodsValidator get cocoapodsValidator => context[CocoaPodsValidator];
+IOSWorkflow get iosWorkflow => context.get<IOSWorkflow>();
+IOSValidator get iosValidator => context.get<IOSValidator>();
+CocoaPodsValidator get cocoapodsValidator => context.get<CocoaPodsValidator>();
 
 class IOSWorkflow implements Workflow {
   const IOSWorkflow();

packages/flutter_tools/lib/src/ios/mac.dart

@@ -31,9 +31,9 @@ import 'xcodeproj.dart';
 const int kXcodeRequiredVersionMajor = 9;
 const int kXcodeRequiredVersionMinor = 0;
 
-IMobileDevice get iMobileDevice => context[IMobileDevice];
-PlistBuddy get plistBuddy => context[PlistBuddy];
-Xcode get xcode => context[Xcode];
+IMobileDevice get iMobileDevice => context.get<IMobileDevice>();
+PlistBuddy get plistBuddy => context.get<PlistBuddy>();
+Xcode get xcode => context.get<Xcode>();
 
 class PlistBuddy {
   const PlistBuddy();

packages/flutter_tools/lib/src/ios/simulators.dart

@@ -41,7 +41,7 @@ class IOSSimulators extends PollingDeviceDiscovery {
 
 class IOSSimulatorUtils {
   /// Returns [IOSSimulatorUtils] active in the current app context (i.e. zone).
-  static IOSSimulatorUtils get instance => context[IOSSimulatorUtils];
+  static IOSSimulatorUtils get instance => context.get<IOSSimulatorUtils>();
 
   List<IOSSimulator> getAttachedDevices() {
     if (!xcode.isInstalledAndMeetsVersionCheck)
@@ -56,7 +56,7 @@ class IOSSimulatorUtils {
 /// A wrapper around the `simctl` command line tool.
 class SimControl {
   /// Returns [SimControl] active in the current app context (i.e. zone).
-  static SimControl get instance => context[SimControl];
+  static SimControl get instance => context.get<SimControl>();
 
   /// Runs `simctl list --json` and returns the JSON of the corresponding
   /// [section].

packages/flutter_tools/lib/src/ios/xcodeproj.dart

@@ -127,7 +127,7 @@ Future<void> updateGeneratedXcodeProperties({
   generatedXcodePropertiesFile.writeAsStringSync(localsBuffer.toString());
 }
 
-XcodeProjectInterpreter get xcodeProjectInterpreter => context[XcodeProjectInterpreter];
+XcodeProjectInterpreter get xcodeProjectInterpreter => context.get<XcodeProjectInterpreter>();
 
 /// Interpreter of Xcode projects.
 class XcodeProjectInterpreter {

packages/flutter_tools/lib/src/linux/linux_workflow.dart

@@ -8,7 +8,7 @@ import '../desktop.dart';
 import '../doctor.dart';
 
 /// The [WindowsWorkflow] instance.
-LinuxWorkflow get linuxWorkflow => context[LinuxWorkflow];
+LinuxWorkflow get linuxWorkflow => context.get<LinuxWorkflow>();
 
 /// The windows-specific implementation of a [Workflow].
 ///

packages/flutter_tools/lib/src/macos/macos_workflow.dart

@@ -8,7 +8,7 @@ import '../desktop.dart';
 import '../doctor.dart';
 
 /// The [MacOSWorkflow] instance.
-MacOSWorkflow get macOSWorkflow => context[MacOSWorkflow];
+MacOSWorkflow get macOSWorkflow => context.get<MacOSWorkflow>();
 
 /// The macOS-specific implementation of a [Workflow].
 ///

packages/flutter_tools/lib/src/run_hot.dart

@@ -40,7 +40,7 @@ class HotRunnerConfig {
   }
 }
 
-HotRunnerConfig get hotRunnerConfig => context[HotRunnerConfig];
+HotRunnerConfig get hotRunnerConfig => context.get<HotRunnerConfig>();
 
 const bool kHotReloadDefault = true;
 

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

@@ -77,7 +77,7 @@ abstract class FlutterCommand extends Command<void> {
   /// The currently executing command (or sub-command).
   ///
   /// Will be `null` until the top-most command has begun execution.
-  static FlutterCommand get current => context[FlutterCommand];
+  static FlutterCommand get current => context.get<FlutterCommand>();
 
   /// The option name for a custom observatory port.
   static const String observatoryPortOption = 'observatory-port';

packages/flutter_tools/lib/src/usage.dart

@@ -55,7 +55,7 @@ class Usage {
   }
 
   /// Returns [Usage] active in the current app context.
-  static Usage get instance => context[Usage];
+  static Usage get instance => context.get<Usage>();
 
   Analytics _analytics;
 

packages/flutter_tools/lib/src/version.dart

@@ -179,7 +179,7 @@ class FlutterVersion {
       await _run(<String>['git', 'remote', 'remove', _versionCheckRemote]);
   }
 
-  static FlutterVersion get instance => context[FlutterVersion];
+  static FlutterVersion get instance => context.get<FlutterVersion>();
 
   /// Return a short string for the version (e.g. `master/0.0.59-pre.92`, `scroll_refactor/a76bc8e22b`).
   String getVersionString({ bool redactUnknownBranches = false }) {

packages/flutter_tools/lib/src/vmservice.dart

@@ -82,7 +82,7 @@ Future<StreamChannel<String>> _defaultOpenChannel(Uri uri, {io.CompressionOption
       delay *= 2;
   }
 
-  final WebSocketConnector constructor = context[WebSocketConnector] ?? io.WebSocket.connect;
+  final WebSocketConnector constructor = context.get<WebSocketConnector>() ?? io.WebSocket.connect;
   while (socket == null) {
     attempts += 1;
     try {

packages/flutter_tools/lib/src/web/compile.dart

@@ -15,7 +15,7 @@ import '../convert.dart';
 import '../globals.dart';
 
 /// The [WebCompiler] instance.
-WebCompiler get webCompiler => context[WebCompiler];
+WebCompiler get webCompiler => context.get<WebCompiler>();
 
 /// A wrapper around dart2js for web compilation.
 class WebCompiler {

packages/flutter_tools/lib/src/web/web_device.dart

@@ -16,7 +16,7 @@ import '../project.dart';
 import '../version.dart';
 import '../web/compile.dart';
 
-ChromeLauncher get chromeLauncher => context[ChromeLauncher];
+ChromeLauncher get chromeLauncher => context.get<ChromeLauncher>();
 
 /// Only launch or display web devices if `FLUTTER_WEB`
 /// environment variable is set to true.

packages/flutter_tools/lib/src/windows/windows_workflow.dart

@@ -8,7 +8,7 @@ import '../desktop.dart';
 import '../doctor.dart';
 
 /// The [WindowsWorkflow] instance.
-WindowsWorkflow get windowsWorkflow => context[WindowsWorkflow];
+WindowsWorkflow get windowsWorkflow => context.get<WindowsWorkflow>();
 
 /// The windows-specific implementation of a [Workflow].
 ///

packages/flutter_tools/test/application_package_test.dart

@@ -146,21 +146,21 @@ void main() {
     testUsingContext('Error when parsing manifest with no Activity that has enabled set to true nor has no value for its enabled field', () {
       final ApkManifestData data = ApkManifestData.parseFromXmlDump(_aaptDataWithNoEnabledActivity);
       expect(data, isNull);
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
       expect(
           logger.errorText, 'Error running io.flutter.examples.hello_world. Default activity not found\n');
     }, overrides: noColorTerminalOverride);
     testUsingContext('Error when parsing manifest with no Activity that has action set to android.intent.action.MAIN', () {
       final ApkManifestData data = ApkManifestData.parseFromXmlDump(_aaptDataWithNoMainActivity);
       expect(data, isNull);
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
       expect(
           logger.errorText, 'Error running io.flutter.examples.hello_world. Default activity not found\n');
     }, overrides: noColorTerminalOverride);
     testUsingContext('Error when parsing manifest with no Activity that has category set to android.intent.category.LAUNCHER', () {
       final ApkManifestData data = ApkManifestData.parseFromXmlDump(_aaptDataWithNoLauncherActivity);
       expect(data, isNull);
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
       expect(
           logger.errorText, 'Error running io.flutter.examples.hello_world. Default activity not found\n');
     }, overrides: noColorTerminalOverride);
@@ -176,7 +176,7 @@ void main() {
       final PrebuiltIOSApp iosApp =
           IOSApp.fromPrebuiltApp(fs.file('not_existing.ipa'));
       expect(iosApp, isNull);
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
       expect(
         logger.errorText,
         'File "not_existing.ipa" does not exist. Use an app bundle or an ipa.\n',
@@ -187,7 +187,7 @@ void main() {
       final PrebuiltIOSApp iosApp =
           IOSApp.fromPrebuiltApp(fs.file('regular_folder'));
       expect(iosApp, isNull);
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
       expect(
           logger.errorText, 'Folder "regular_folder" is not an app bundle.\n');
     }, overrides: overrides);
@@ -195,7 +195,7 @@ void main() {
       fs.directory('bundle.app').createSync();
       final PrebuiltIOSApp iosApp = IOSApp.fromPrebuiltApp(fs.file('bundle.app'));
       expect(iosApp, isNull);
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
       expect(
         logger.errorText,
         'Invalid prebuilt iOS app. Does not contain Info.plist.\n',
@@ -206,7 +206,7 @@ void main() {
       fs.file('bundle.app/Info.plist').writeAsStringSync(badPlistData);
       final PrebuiltIOSApp iosApp = IOSApp.fromPrebuiltApp(fs.file('bundle.app'));
       expect(iosApp, isNull);
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
       expect(
         logger.errorText,
         contains(
@@ -217,7 +217,7 @@ void main() {
       fs.directory('bundle.app').createSync();
       fs.file('bundle.app/Info.plist').writeAsStringSync(plistData);
       final PrebuiltIOSApp iosApp = IOSApp.fromPrebuiltApp(fs.file('bundle.app'));
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
       expect(logger.errorText, isEmpty);
       expect(iosApp.bundleDir.path, 'bundle.app');
       expect(iosApp.id, 'fooBundleId');
@@ -228,7 +228,7 @@ void main() {
       when(os.unzip(fs.file('app.ipa'), any)).thenAnswer((Invocation _) { });
       final PrebuiltIOSApp iosApp = IOSApp.fromPrebuiltApp(fs.file('app.ipa'));
       expect(iosApp, isNull);
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
       expect(
         logger.errorText,
         'Invalid prebuilt iOS ipa. Does not contain a "Payload" directory.\n',
@@ -251,7 +251,7 @@ void main() {
       });
       final PrebuiltIOSApp iosApp = IOSApp.fromPrebuiltApp(fs.file('app.ipa'));
       expect(iosApp, isNull);
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
       expect(logger.errorText,
           'Invalid prebuilt iOS ipa. Does not contain a single app bundle.\n');
     }, overrides: overrides);
@@ -271,7 +271,7 @@ void main() {
             .writeAsStringSync(plistData);
       });
       final PrebuiltIOSApp iosApp = IOSApp.fromPrebuiltApp(fs.file('app.ipa'));
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
       expect(logger.errorText, isEmpty);
       expect(iosApp.bundleDir.path, endsWith('bundle.app'));
       expect(iosApp.id, 'fooBundleId');

packages/flutter_tools/test/base/context_test.dart

@@ -80,7 +80,7 @@ void main() {
         await context.run<void>(
           body: () {
             outer.future.then<void>((_) {
-              value = context[String];
+              value = context.get<String>();
               inner.complete();
             });
           },
@@ -99,10 +99,10 @@ void main() {
         String value;
         await context.run<void>(
           body: () async {
-            final StringBuffer buf = StringBuffer(context[String]);
-            buf.write(context[String]);
+            final StringBuffer buf = StringBuffer(context.get<String>());
+            buf.write(context.get<String>());
             await context.run<void>(body: () {
-              buf.write(context[String]);
+              buf.write(context.get<String>());
             });
             value = buf.toString();
           },
@@ -122,10 +122,10 @@ void main() {
         String value;
         await context.run(
           body: () async {
-            final StringBuffer buf = StringBuffer(context[String]);
-            buf.write(context[String]);
+            final StringBuffer buf = StringBuffer(context.get<String>());
+            buf.write(context.get<String>());
             await context.run<void>(body: () {
-              buf.write(context[String]);
+              buf.write(context.get<String>());
             });
             value = buf.toString();
           },
@@ -142,7 +142,7 @@ void main() {
 
       test('returns null if generated value is null', () async {
         final String value = await context.run<String>(
-          body: () => context[String],
+          body: () => context.get<String>(),
           overrides: <Type, Generator>{
             String: () => null,
           },
@@ -153,12 +153,12 @@ void main() {
       test('throws if generator has dependency cycle', () async {
         final Future<String> value = context.run<String>(
           body: () async {
-            return context[String];
+            return context.get<String>();
           },
           fallbacks: <Type, Generator>{
-            int: () => int.parse(context[String]),
-            String: () => '${context[double]}',
-            double: () => (context[int] as int) * 1.0, // ignore: avoid_as
+            int: () => int.parse(context.get<String>()),
+            String: () => '${context.get<double>()}',
+            double: () => context.get<int>() * 1.0,
           },
         );
         try {
@@ -197,7 +197,7 @@ void main() {
               return context.run<String>(
                 body: () {
                   called = true;
-                  return context[String];
+                  return context.get<String>();
                 },
                 fallbacks: <Type, Generator>{
                   String: () => 'child',
@@ -216,7 +216,7 @@ void main() {
               return context.run<String>(
                 body: () {
                   called = true;
-                  return context[String];
+                  return context.get<String>();
                 },
                 fallbacks: <Type, Generator>{
                   String: () {
@@ -238,11 +238,11 @@ void main() {
         test('may depend on one another', () async {
           final String value = await context.run<String>(
             body: () {
-              return context[String];
+              return context.get<String>();
             },
             fallbacks: <Type, Generator>{
               int: () => 123,
-              String: () => '-${context[int]}-',
+              String: () => '-${context.get<int>()}-',
             },
           );
           expect(value, '-123-');
@@ -255,7 +255,7 @@ void main() {
           final String value = await context.run<String>(
             body: () {
               return context.run<String>(
-                body: () => context[String],
+                body: () => context.get<String>(),
                 overrides: <Type, Generator>{
                   String: () => 'child',
                 },

packages/flutter_tools/test/base/logger_test.dart

@@ -163,7 +163,7 @@ void main() {
       testUsingContext('Stdout startProgress on colored terminal for $testOs', () async {
         bool done = false;
         FakeAsync().run((FakeAsync time) {
-          final Logger logger = context[Logger];
+          final Logger logger = context.get<Logger>();
           final Status status = logger.startProgress(
             'Hello',
             progressId: null,
@@ -191,7 +191,7 @@ void main() {
       testUsingContext('Stdout startProgress on colored terminal pauses on $testOs', () async {
         bool done = false;
         FakeAsync().run((FakeAsync time) {
-          final Logger logger = context[Logger];
+          final Logger logger = context.get<Logger>();
           final Status status = logger.startProgress(
             'Knock Knock, Who\'s There',
             timeout: const Duration(days: 10),
@@ -368,7 +368,7 @@ void main() {
     List<String> outputStderr() => mockStdio.writtenToStderr.join('').split('\n');
 
     testUsingContext('Error logs are wrapped', () async {
-      final Logger logger = context[Logger];
+      final Logger logger = context.get<Logger>();
       logger.printError('0123456789' * 15);
       final List<String> lines = outputStderr();
       expect(outputStdout().length, equals(1));
@@ -385,7 +385,7 @@ void main() {
     });
 
     testUsingContext('Error logs are wrapped and can be indented.', () async {
-      final Logger logger = context[Logger];
+      final Logger logger = context.get<Logger>();
       logger.printError('0123456789' * 15, indent: 5);
       final List<String> lines = outputStderr();
       expect(outputStdout().length, equals(1));
@@ -405,7 +405,7 @@ void main() {
     });
 
     testUsingContext('Error logs are wrapped and can have hanging indent.', () async {
-      final Logger logger = context[Logger];
+      final Logger logger = context.get<Logger>();
       logger.printError('0123456789' * 15, hangingIndent: 5);
       final List<String> lines = outputStderr();
       expect(outputStdout().length, equals(1));
@@ -425,7 +425,7 @@ void main() {
     });
 
     testUsingContext('Error logs are wrapped, indented, and can have hanging indent.', () async {
-      final Logger logger = context[Logger];
+      final Logger logger = context.get<Logger>();
       logger.printError('0123456789' * 15, indent: 4, hangingIndent: 5);
       final List<String> lines = outputStderr();
       expect(outputStdout().length, equals(1));
@@ -445,7 +445,7 @@ void main() {
     });
 
     testUsingContext('Stdout logs are wrapped', () async {
-      final Logger logger = context[Logger];
+      final Logger logger = context.get<Logger>();
       logger.printStatus('0123456789' * 15);
       final List<String> lines = outputStdout();
       expect(outputStderr().length, equals(1));
@@ -462,7 +462,7 @@ void main() {
     });
 
     testUsingContext('Stdout logs are wrapped and can be indented.', () async {
-      final Logger logger = context[Logger];
+      final Logger logger = context.get<Logger>();
       logger.printStatus('0123456789' * 15, indent: 5);
       final List<String> lines = outputStdout();
       expect(outputStderr().length, equals(1));
@@ -482,7 +482,7 @@ void main() {
     });
 
     testUsingContext('Stdout logs are wrapped and can have hanging indent.', () async {
-      final Logger logger = context[Logger];
+      final Logger logger = context.get<Logger>();
       logger.printStatus('0123456789' * 15, hangingIndent: 5);
       final List<String> lines = outputStdout();
       expect(outputStderr().length, equals(1));
@@ -502,7 +502,7 @@ void main() {
     });
 
     testUsingContext('Stdout logs are wrapped, indented, and can have hanging indent.', () async {
-      final Logger logger = context[Logger];
+      final Logger logger = context.get<Logger>();
       logger.printStatus('0123456789' * 15, indent: 4, hangingIndent: 5);
       final List<String> lines = outputStdout();
       expect(outputStderr().length, equals(1));
@@ -522,7 +522,7 @@ void main() {
     });
 
     testUsingContext('Error logs are red', () async {
-      final Logger logger = context[Logger];
+      final Logger logger = context.get<Logger>();
       logger.printError('Pants on fire!');
       final List<String> lines = outputStderr();
       expect(outputStdout().length, equals(1));
@@ -536,7 +536,7 @@ void main() {
     });
 
     testUsingContext('Stdout logs are not colored', () async {
-      final Logger logger = context[Logger];
+      final Logger logger = context.get<Logger>();
       logger.printStatus('All good.');
       final List<String> lines = outputStdout();
       expect(outputStderr().length, equals(1));
@@ -549,7 +549,7 @@ void main() {
     });
 
     testUsingContext('Stdout printStatus handle null inputs on colored terminal', () async {
-      final Logger logger = context[Logger];
+      final Logger logger = context.get<Logger>();
       logger.printStatus(
         null,
         emphasis: null,
@@ -568,7 +568,7 @@ void main() {
     });
 
     testUsingContext('Stdout printStatus handle null inputs on non-color terminal', () async {
-      final Logger logger = context[Logger];
+      final Logger logger = context.get<Logger>();
       logger.printStatus(
         null,
         emphasis: null,
@@ -590,7 +590,7 @@ void main() {
     testUsingContext('Stdout startProgress on non-color terminal', () async {
       bool done = false;
       FakeAsync().run((FakeAsync time) {
-        final Logger logger = context[Logger];
+        final Logger logger = context.get<Logger>();
         final Status status = logger.startProgress(
           'Hello',
           progressId: null,
@@ -661,7 +661,7 @@ void main() {
     }, overrides: <Type, Generator>{Stdio: () => mockStdio, Platform: _kNoAnsiPlatform});
 
     testUsingContext('sequential startProgress calls with StdoutLogger', () async {
-      final Logger logger = context[Logger];
+      final Logger logger = context.get<Logger>();
       logger.startProgress('AAA', timeout: timeoutConfiguration.fastOperation)..stop();
       logger.startProgress('BBB', timeout: timeoutConfiguration.fastOperation)..stop();
       final List<String> output = outputStdout();
@@ -679,7 +679,7 @@ void main() {
     });
 
     testUsingContext('sequential startProgress calls with VerboseLogger and StdoutLogger', () async {
-      final Logger logger = context[Logger];
+      final Logger logger = context.get<Logger>();
       logger.startProgress('AAA', timeout: timeoutConfiguration.fastOperation)..stop();
       logger.startProgress('BBB', timeout: timeoutConfiguration.fastOperation)..stop();
       expect(outputStdout(), <Matcher>[
@@ -696,7 +696,7 @@ void main() {
     });
 
     testUsingContext('sequential startProgress calls with BufferLogger', () async {
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
       logger.startProgress('AAA', timeout: timeoutConfiguration.fastOperation)..stop();
       logger.startProgress('BBB', timeout: timeoutConfiguration.fastOperation)..stop();
       expect(logger.statusText, 'AAA\nBBB\n');

packages/flutter_tools/test/commands/config_test.dart

@@ -25,7 +25,7 @@ void main() {
 
   group('config', () {
     testUsingContext('machine flag', () async {
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
       final ConfigCommand command = ConfigCommand();
       await command.handleMachine();
 

packages/flutter_tools/test/compile_test.dart

@@ -114,7 +114,7 @@ example:org-dartlang-app:/
     });
 
     testUsingContext('single dart successful compilation', () async {
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
       when(mockFrontendServer.stdout)
           .thenAnswer((Invocation invocation) => Stream<List<int>>.fromFuture(
             Future<List<int>>.value(utf8.encode(
@@ -137,7 +137,7 @@ example:org-dartlang-app:/
     });
 
     testUsingContext('single dart failed compilation', () async {
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
 
       when(mockFrontendServer.stdout)
           .thenAnswer((Invocation invocation) => Stream<List<int>>.fromFuture(
@@ -163,7 +163,7 @@ example:org-dartlang-app:/
     testUsingContext('single dart abnormal compiler termination', () async {
       when(mockFrontendServer.exitCode).thenAnswer((_) async => 255);
 
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
 
       when(mockFrontendServer.stdout)
           .thenAnswer((Invocation invocation) => Stream<List<int>>.fromFuture(
@@ -221,7 +221,7 @@ example:org-dartlang-app:/
     });
 
     testUsingContext('single dart compile', () async {
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
 
       when(mockFrontendServer.stdout)
           .thenAnswer((Invocation invocation) => Stream<List<int>>.fromFuture(
@@ -265,7 +265,7 @@ example:org-dartlang-app:/
     });
 
     testUsingContext('compile and recompile', () async {
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
 
       final StreamController<List<int>> streamController = StreamController<List<int>>();
       when(mockFrontendServer.stdout)
@@ -309,7 +309,7 @@ example:org-dartlang-app:/
     });
 
     testUsingContext('compile and recompile twice', () async {
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
 
       final StreamController<List<int>> streamController = StreamController<List<int>>();
       when(mockFrontendServer.stdout)
@@ -380,7 +380,7 @@ example:org-dartlang-app:/
     });
 
     testUsingContext('compile single expression', () async {
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
 
       final Completer<List<int>> compileResponseCompleter =
           Completer<List<int>>();
@@ -432,7 +432,7 @@ example:org-dartlang-app:/
     });
 
     testUsingContext('compile expressions without awaiting', () async {
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
 
       final Completer<List<int>> compileResponseCompleter = Completer<List<int>>();
       final Completer<List<int>> compileExpressionResponseCompleter1 = Completer<List<int>>();

packages/flutter_tools/test/crash_reporting_test.dart

@@ -109,7 +109,7 @@ void main() {
       expect(fields['error_runtime_type'], 'StateError');
       expect(fields['error_message'], 'Bad state: Test bad state error');
 
-      final BufferLogger logger = context[Logger];
+      final BufferLogger logger = context.get<Logger>();
       expect(logger.statusText, 'Sending crash report to Google.\n'
           'Crash report sent (report ID: test-report-id)\n');
 

packages/flutter_tools/test/dart/pub_get_test.dart

@@ -27,7 +27,7 @@ void main() {
   testUsingContext('pub get 69', () async {
     String error;
 
-    final MockProcessManager processMock = context[ProcessManager];
+    final MockProcessManager processMock = context.get<ProcessManager>();
 
     FakeAsync().run((FakeAsync time) {
       expect(processMock.lastPubEnvironment, isNull);
@@ -95,8 +95,8 @@ void main() {
   testUsingContext('pub cache in root is used', () async {
     String error;
 
-    final MockProcessManager processMock = context[ProcessManager];
-    final MockFileSystem fsMock = context[FileSystem];
+    final MockProcessManager processMock = context.get<ProcessManager>() as MockProcessManager;
+    final MockFileSystem fsMock = context.get<FileSystem>() as MockFileSystem;
 
     FakeAsync().run((FakeAsync time) {
       MockDirectory.findCache = true;
@@ -122,7 +122,7 @@ void main() {
   testUsingContext('pub cache in environment is used', () async {
     String error;
 
-    final MockProcessManager processMock = context[ProcessManager];
+    final MockProcessManager processMock = context.get<ProcessManager>();
 
     FakeAsync().run((FakeAsync time) {
       MockDirectory.findCache = true;

packages/flutter_tools/test/src/context.dart

@@ -30,10 +30,10 @@ import 'common.dart';
 export 'package:flutter_tools/src/base/context.dart' show Generator;
 
 /// Return the test logger. This assumes that the current Logger is a BufferLogger.
-BufferLogger get testLogger => context[Logger];
+BufferLogger get testLogger => context.get<Logger>();
 
-MockDeviceManager get testDeviceManager => context[DeviceManager];
-MockDoctor get testDoctor => context[Doctor];
+MockDeviceManager get testDeviceManager => context.get<DeviceManager>();
+MockDoctor get testDoctor => context.get<Doctor>();
 
 typedef ContextInitializer = void Function(AppContext testContext);
 
@@ -126,8 +126,8 @@ void testUsingContext(
 }
 
 void _printBufferedErrors(AppContext testContext) {
-  if (testContext[Logger] is BufferLogger) {
-    final BufferLogger bufferLogger = testContext[Logger];
+  if (testContext.get<Logger>() is BufferLogger) {
+    final BufferLogger bufferLogger = testContext.get<Logger>();
     if (bufferLogger.errorText.isNotEmpty)
       print(bufferLogger.errorText);
     bufferLogger.clear();

packages/flutter_tools/test/version_test.dart

@@ -414,7 +414,7 @@ void main() {
 }
 
 void _expectVersionMessage(String message) {
-  final BufferLogger logger = context[Logger];
+  final BufferLogger logger = context.get<Logger>();
   expect(logger.statusText.trim(), message.trim());
   logger.clear();
 }