diff --git a/packages/flutter_tools/lib/src/base/common.dart b/packages/flutter_tools/lib/src/base/common.dart
index f2a891c33a5..e124cfab93d 100644
--- a/packages/flutter_tools/lib/src/base/common.dart
+++ b/packages/flutter_tools/lib/src/base/common.dart
@@ -17,7 +17,7 @@ Never throwToolExit(String message, { int? exitCode }) {
 class ToolExit implements Exception {
   ToolExit(this.message, { this.exitCode });
 
-  final String message;
+  final String? message;
   final int? exitCode;
 
   @override
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 c0dfc4c452a..773d33ff7fa 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
@@ -24,6 +24,7 @@ import 'package:process/process.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fake_process_manager.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   setUpAll(() {
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/assemble_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/assemble_test.dart
index cdfd4e2b71c..e900bf68792 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/assemble_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/assemble_test.dart
@@ -19,6 +19,7 @@ import 'package:flutter_tools/src/globals_null_migrated.dart' as globals;
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 import '../../src/testbed.dart';
 
 void main() {
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/attach_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/attach_test.dart
index 6caaf95dae7..22bfbc531c3 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/attach_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/attach_test.dart
@@ -29,8 +29,10 @@ import 'package:vm_service/vm_service.dart' as vm_service;
 
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/fake_vm_services.dart';
 import '../../src/fakes.dart';
 import '../../src/mocks.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 final vm_service.Isolate fakeUnpausedIsolate = vm_service.Isolate(
   id: '1',
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/build_fuchsia_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/build_fuchsia_test.dart
index 8c9af2d5058..cd934bcb00b 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/build_fuchsia_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/build_fuchsia_test.dart
@@ -22,6 +22,7 @@ import 'package:test/fake.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 // Defined globally for fakes to use.
 FileSystem fileSystem;
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/build_ios_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/build_ios_test.dart
index 0bc22fd3c4c..1f613b44ac7 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/build_ios_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/build_ios_test.dart
@@ -15,6 +15,7 @@ import 'package:process/process.dart';
 
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/test_flutter_command_runner.dart';
 import '../../src/testbed.dart';
 
 class FakeXcodeProjectInterpreterWithBuildSettings extends FakeXcodeProjectInterpreter {
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/build_ipa_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/build_ipa_test.dart
index 90706fd7ec6..7168bb7eeb3 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/build_ipa_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/build_ipa_test.dart
@@ -15,6 +15,7 @@ import 'package:flutter_tools/src/reporting/reporting.dart';
 
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 class FakeXcodeProjectInterpreterWithBuildSettings extends FakeXcodeProjectInterpreter {
   @override
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/build_linux_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/build_linux_test.dart
index 39c7b5c1e81..c19dbc866c3 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/build_linux_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/build_linux_test.dart
@@ -23,6 +23,7 @@ import 'package:test/fake.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 const String _kTestFlutterRoot = '/flutter';
 
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/build_macos_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/build_macos_test.dart
index 7e9b9c962d1..3a1767973e2 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/build_macos_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/build_macos_test.dart
@@ -24,6 +24,7 @@ import 'package:flutter_tools/src/reporting/reporting.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 class FakeXcodeProjectInterpreterWithProfile extends FakeXcodeProjectInterpreter {
   @override
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/build_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/build_test.dart
index 92168505a32..6a20cf7c7ef 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/build_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/build_test.dart
@@ -10,6 +10,7 @@ import 'package:flutter_tools/src/runner/flutter_command.dart';
 
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   testUsingContext('obfuscate requires split-debug-info', () {
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/build_web_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/build_web_test.dart
index 68a6fefb669..830eb5e2861 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/build_web_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/build_web_test.dart
@@ -22,6 +22,7 @@ import 'package:flutter_tools/src/web/compile.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   FileSystem fileSystem;
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/build_windows_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/build_windows_test.dart
index 6d7ad3bf5b3..34aa3be994f 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/build_windows_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/build_windows_test.dart
@@ -20,6 +20,7 @@ import 'package:process/process.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 import '../../src/testbed.dart';
 
 const String flutterRoot = r'C:\flutter';
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/config_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/config_test.dart
index 78ba006c59c..7df74986047 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/config_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/config_test.dart
@@ -20,6 +20,7 @@ import 'package:test/fake.dart';
 
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   FakeAndroidStudio fakeAndroidStudio;
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/create_usage_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/create_usage_test.dart
index e77f0e561e2..962782655e7 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/create_usage_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/create_usage_test.dart
@@ -16,6 +16,7 @@ import 'package:flutter_tools/src/globals_null_migrated.dart' as globals;
 
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/test_flutter_command_runner.dart';
 import '../../src/testbed.dart';
 
 void main() {
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/daemon_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/daemon_test.dart
index e1f4ee06f4f..6cb2609c753 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/daemon_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/daemon_test.dart
@@ -24,6 +24,21 @@ import '../../src/context.dart';
 import '../../src/fakes.dart';
 import '../../src/mocks.dart';
 
+/// Runs a callback using FakeAsync.run while continually pumping the
+/// microtask queue. This avoids a deadlock when tests `await` a Future
+/// which queues a microtask that will not be processed unless the queue
+/// is flushed.
+Future<T> _runFakeAsync<T>(Future<T> Function(FakeAsync time) f) async {
+  return FakeAsync().run((FakeAsync time) async {
+    bool pump = true;
+    final Future<T> future = f(time).whenComplete(() => pump = false);
+    while (pump) {
+      time.flushMicrotasks();
+    }
+    return future;
+  });
+}
+
 void main() {
   Daemon daemon;
   NotifyingLogger notifyingLogger;
@@ -426,7 +441,7 @@ void main() {
     testWithoutContext(
         'debounces/merges same operation type and returns same result',
         () async {
-      await runFakeAsync((FakeAsync time) async {
+      await _runFakeAsync((FakeAsync time) async {
         final List<Future<int>> operations = <Future<int>>[
           queue.queueAndDebounce('OP1', debounceDuration, () async => 1),
           queue.queueAndDebounce('OP1', debounceDuration, () async => 2),
@@ -441,7 +456,7 @@ void main() {
 
     testWithoutContext('does not merge results outside of the debounce duration',
         () async {
-      await runFakeAsync((FakeAsync time) async {
+      await _runFakeAsync((FakeAsync time) async {
         final List<Future<int>> operations = <Future<int>>[
           queue.queueAndDebounce('OP1', debounceDuration, () async => 1),
           Future<int>.delayed(debounceDuration * 2).then((_) =>
@@ -457,7 +472,7 @@ void main() {
 
     testWithoutContext('does not merge results of different operations',
         () async {
-      await runFakeAsync((FakeAsync time) async {
+      await _runFakeAsync((FakeAsync time) async {
         final List<Future<int>> operations = <Future<int>>[
           queue.queueAndDebounce('OP1', debounceDuration, () async => 1),
           queue.queueAndDebounce('OP2', debounceDuration, () async => 2),
@@ -484,7 +499,7 @@ void main() {
         return ret;
       }
 
-      await runFakeAsync((FakeAsync time) async {
+      await _runFakeAsync((FakeAsync time) async {
         final List<Future<int>> operations = <Future<int>>[
           queue.queueAndDebounce('OP1', debounceDuration, () => f(1)),
           queue.queueAndDebounce('OP2', debounceDuration, () => f(2)),
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/devices_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/devices_test.dart
index 9b89a4ac104..95cc7014b34 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/devices_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/devices_test.dart
@@ -16,6 +16,7 @@ import 'package:flutter_tools/src/globals.dart' as globals;
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fake_devices.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   group('devices', () {
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/doctor_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/doctor_test.dart
index 84c02051f73..3c7e4a67c5e 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/doctor_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/doctor_test.dart
@@ -35,6 +35,7 @@ import 'package:fake_async/fake_async.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 FakePlatform _kNoColorOutputPlatform() => FakePlatform(
   localeName: 'en_US.UTF-8',
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/downgrade_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/downgrade_test.dart
index 5c710587414..4b69122b404 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/downgrade_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/downgrade_test.dart
@@ -17,6 +17,7 @@ import 'package:mockito/mockito.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   FileSystem fileSystem;
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/drive_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/drive_test.dart
index 73ab79e0c9c..092ef2496ed 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/drive_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/drive_test.dart
@@ -17,6 +17,7 @@ import 'package:test/fake.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   FileSystem fileSystem;
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/generate_localizations_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/generate_localizations_test.dart
index 2a250328e55..94fe77cbc41 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/generate_localizations_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/generate_localizations_test.dart
@@ -14,6 +14,7 @@ import 'package:flutter_tools/src/commands/generate_localizations.dart';
 import '../../integration.shard/test_data/basic_project.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   testUsingContext('default l10n settings', () async {
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/ide_config_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/ide_config_test.dart
index 289fb6a76af..721a509b81f 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/ide_config_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/ide_config_test.dart
@@ -13,6 +13,7 @@ import 'package:flutter_tools/src/globals_null_migrated.dart' as globals;
 
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   group('ide_config', () {
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/install_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/install_test.dart
index e2121b68b1a..6c848c3818a 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/install_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/install_test.dart
@@ -17,6 +17,7 @@ import 'package:mockito/mockito.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/mocks.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   group('install', () {
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 bf9101c614a..835689c5dd6 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/precache_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/precache_test.dart
@@ -13,6 +13,7 @@ import 'package:mockito/mockito.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   MockCache cache;
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/pub_get_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/pub_get_test.dart
index b73360ed492..30063e492a6 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/pub_get_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/pub_get_test.dart
@@ -16,6 +16,7 @@ import 'package:test/fake.dart';
 
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   FileSystem fileSystem;
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/run_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/run_test.dart
index 81029893037..1a81e0073bb 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/run_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/run_test.dart
@@ -32,6 +32,7 @@ import 'package:vm_service/vm_service.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   group('run', () {
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/shell_completion_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/shell_completion_test.dart
index f98ba6ae608..5aadc2bd4be 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/shell_completion_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/shell_completion_test.dart
@@ -15,6 +15,7 @@ import 'package:flutter_tools/src/globals_null_migrated.dart' as globals;
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   group('shell_completion', () {
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/symbolize_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/symbolize_test.dart
index 6422c280cbb..493f046fa0a 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/symbolize_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/symbolize_test.dart
@@ -21,6 +21,7 @@ import 'package:test/fake.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   MemoryFileSystem fileSystem;
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/test_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/test_test.dart
index d4ff0aa7b2e..13acca790c7 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/test_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/test_test.dart
@@ -25,6 +25,7 @@ import 'package:process/process.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fake_devices.dart';
+import '../../src/test_flutter_command_runner.dart';
 import '../../src/testbed.dart';
 
 const String _pubspecContents = '''
diff --git a/packages/flutter_tools/test/commands.shard/permeable/analyze_once_test.dart b/packages/flutter_tools/test/commands.shard/permeable/analyze_once_test.dart
index 8255af42db1..f0acfdfaec0 100644
--- a/packages/flutter_tools/test/commands.shard/permeable/analyze_once_test.dart
+++ b/packages/flutter_tools/test/commands.shard/permeable/analyze_once_test.dart
@@ -23,6 +23,7 @@ import 'package:process/process.dart';
 
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 final Platform _kNoColorTerminalPlatform = FakePlatform(stdoutSupportsAnsi: false);
 
diff --git a/packages/flutter_tools/test/commands.shard/permeable/build_aar_test.dart b/packages/flutter_tools/test/commands.shard/permeable/build_aar_test.dart
index bdcba7d5a72..da136cb8e27 100644
--- a/packages/flutter_tools/test/commands.shard/permeable/build_aar_test.dart
+++ b/packages/flutter_tools/test/commands.shard/permeable/build_aar_test.dart
@@ -20,6 +20,7 @@ import 'package:test/fake.dart';
 import '../../src/android_common.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   Cache.disableLocking();
diff --git a/packages/flutter_tools/test/commands.shard/permeable/build_apk_test.dart b/packages/flutter_tools/test/commands.shard/permeable/build_apk_test.dart
index fd513c5efbc..252034d6389 100644
--- a/packages/flutter_tools/test/commands.shard/permeable/build_apk_test.dart
+++ b/packages/flutter_tools/test/commands.shard/permeable/build_apk_test.dart
@@ -23,6 +23,7 @@ import '../../src/android_common.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/mocks.dart' hide MockAndroidSdk;
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   Cache.disableLocking();
diff --git a/packages/flutter_tools/test/commands.shard/permeable/build_appbundle_test.dart b/packages/flutter_tools/test/commands.shard/permeable/build_appbundle_test.dart
index bfc43b4ca5b..427e6834b40 100644
--- a/packages/flutter_tools/test/commands.shard/permeable/build_appbundle_test.dart
+++ b/packages/flutter_tools/test/commands.shard/permeable/build_appbundle_test.dart
@@ -18,6 +18,7 @@ import 'package:test/fake.dart';
 import '../../src/android_common.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   Cache.disableLocking();
diff --git a/packages/flutter_tools/test/commands.shard/permeable/build_bundle_test.dart b/packages/flutter_tools/test/commands.shard/permeable/build_bundle_test.dart
index 8d5f7897771..afb1278a880 100644
--- a/packages/flutter_tools/test/commands.shard/permeable/build_bundle_test.dart
+++ b/packages/flutter_tools/test/commands.shard/permeable/build_bundle_test.dart
@@ -21,6 +21,7 @@ import 'package:flutter_tools/src/globals_null_migrated.dart' as globals;
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   Cache.disableLocking();
diff --git a/packages/flutter_tools/test/commands.shard/permeable/create_test.dart b/packages/flutter_tools/test/commands.shard/permeable/create_test.dart
index 3ea586ea923..6b364f06f21 100755
--- a/packages/flutter_tools/test/commands.shard/permeable/create_test.dart
+++ b/packages/flutter_tools/test/commands.shard/permeable/create_test.dart
@@ -32,6 +32,7 @@ import '../../src/context.dart';
 import '../../src/fake_http_client.dart';
 import '../../src/fakes.dart';
 import '../../src/pubspec_schema.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 const String _kNoPlatformsMessage = 'You\'ve created a plugin project that doesn\'t yet support any platforms.\n';
 const String frameworkRevision = '12345678';
diff --git a/packages/flutter_tools/test/commands.shard/permeable/devices_test.dart b/packages/flutter_tools/test/commands.shard/permeable/devices_test.dart
index 4889eda2ea1..e902c5c6488 100644
--- a/packages/flutter_tools/test/commands.shard/permeable/devices_test.dart
+++ b/packages/flutter_tools/test/commands.shard/permeable/devices_test.dart
@@ -21,6 +21,7 @@ import 'package:mockito/mockito.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   setUpAll(() {
diff --git a/packages/flutter_tools/test/commands.shard/permeable/format_test.dart b/packages/flutter_tools/test/commands.shard/permeable/format_test.dart
index 7e6caf8be19..648849fd894 100644
--- a/packages/flutter_tools/test/commands.shard/permeable/format_test.dart
+++ b/packages/flutter_tools/test/commands.shard/permeable/format_test.dart
@@ -12,6 +12,7 @@ import 'package:flutter_tools/src/globals_null_migrated.dart' as globals;
 
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   group('format', () {
diff --git a/packages/flutter_tools/test/commands.shard/permeable/packages_test.dart b/packages/flutter_tools/test/commands.shard/permeable/packages_test.dart
index 0b6fde03280..cefb32a0b49 100644
--- a/packages/flutter_tools/test/commands.shard/permeable/packages_test.dart
+++ b/packages/flutter_tools/test/commands.shard/permeable/packages_test.dart
@@ -24,6 +24,7 @@ import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fake_process_manager.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   Cache.disableLocking();
diff --git a/packages/flutter_tools/test/commands.shard/permeable/upgrade_test.dart b/packages/flutter_tools/test/commands.shard/permeable/upgrade_test.dart
index 8e747b1e077..b6c05159ee5 100644
--- a/packages/flutter_tools/test/commands.shard/permeable/upgrade_test.dart
+++ b/packages/flutter_tools/test/commands.shard/permeable/upgrade_test.dart
@@ -19,6 +19,7 @@ import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fake_process_manager.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   group('UpgradeCommandRunner', () {
diff --git a/packages/flutter_tools/test/general.shard/analytics_test.dart b/packages/flutter_tools/test/general.shard/analytics_test.dart
index fbbafac2f1c..5923bc1c562 100644
--- a/packages/flutter_tools/test/general.shard/analytics_test.dart
+++ b/packages/flutter_tools/test/general.shard/analytics_test.dart
@@ -27,6 +27,7 @@ import 'package:usage/usage_io.dart';
 import '../src/common.dart';
 import '../src/context.dart';
 import '../src/fakes.dart';
+import '../src/test_flutter_command_runner.dart';
 
 void main() {
   setUpAll(() {
diff --git a/packages/flutter_tools/test/general.shard/base/logs_test.dart b/packages/flutter_tools/test/general.shard/base/logs_test.dart
index 21426b37ed9..2eef269d2a9 100644
--- a/packages/flutter_tools/test/general.shard/base/logs_test.dart
+++ b/packages/flutter_tools/test/general.shard/base/logs_test.dart
@@ -10,6 +10,7 @@ import 'package:flutter_tools/src/commands/logs.dart';
 
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/test_flutter_command_runner.dart';
 
 void main() {
   group('logs', () {
diff --git a/packages/flutter_tools/test/general.shard/channel_test.dart b/packages/flutter_tools/test/general.shard/channel_test.dart
index 6250d460ece..0ce91666488 100644
--- a/packages/flutter_tools/test/general.shard/channel_test.dart
+++ b/packages/flutter_tools/test/general.shard/channel_test.dart
@@ -14,6 +14,7 @@ import 'package:flutter_tools/src/version.dart';
 
 import '../src/common.dart';
 import '../src/context.dart';
+import '../src/test_flutter_command_runner.dart';
 
 void main() {
   group('channel', () {
diff --git a/packages/flutter_tools/test/general.shard/coverage_collector_test.dart b/packages/flutter_tools/test/general.shard/coverage_collector_test.dart
index 6ae6a71513d..441a6871390 100644
--- a/packages/flutter_tools/test/general.shard/coverage_collector_test.dart
+++ b/packages/flutter_tools/test/general.shard/coverage_collector_test.dart
@@ -8,6 +8,7 @@ import 'package:flutter_tools/src/test/coverage_collector.dart';
 import 'package:vm_service/vm_service.dart' as vm_service;
 
 import '../src/common.dart';
+import '../src/fake_vm_services.dart';
 
 void main() {
   testWithoutContext('Coverage collector Can handle coverage SentinelException', () async {
diff --git a/packages/flutter_tools/test/general.shard/devfs_test.dart b/packages/flutter_tools/test/general.shard/devfs_test.dart
index c20683b7a49..8a96296beff 100644
--- a/packages/flutter_tools/test/general.shard/devfs_test.dart
+++ b/packages/flutter_tools/test/general.shard/devfs_test.dart
@@ -23,6 +23,7 @@ import 'package:package_config/package_config.dart';
 import '../src/common.dart';
 import '../src/context.dart';
 import '../src/fake_http_client.dart';
+import '../src/fake_vm_services.dart';
 
 final FakeVmServiceRequest createDevFSRequest = FakeVmServiceRequest(
   method: '_createDevFS',
diff --git a/packages/flutter_tools/test/general.shard/drive/drive_service_test.dart b/packages/flutter_tools/test/general.shard/drive/drive_service_test.dart
index 8bc70decf97..4bc658eb459 100644
--- a/packages/flutter_tools/test/general.shard/drive/drive_service_test.dart
+++ b/packages/flutter_tools/test/general.shard/drive/drive_service_test.dart
@@ -23,6 +23,7 @@ import 'package:vm_service/vm_service.dart' as vm_service;
 
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/fake_vm_services.dart';
 import '../../src/fakes.dart';
 
 
diff --git a/packages/flutter_tools/test/general.shard/flutter_validator_test.dart b/packages/flutter_tools/test/general.shard/flutter_validator_test.dart
index ce5e34a3536..070508aea5e 100644
--- a/packages/flutter_tools/test/general.shard/flutter_validator_test.dart
+++ b/packages/flutter_tools/test/general.shard/flutter_validator_test.dart
@@ -18,6 +18,18 @@ import '../src/common.dart';
 import '../src/context.dart';
 import '../src/fakes.dart';
 
+/// Matches a doctor validation result.
+Matcher _matchDoctorValidation({
+  ValidationType validationType,
+  String statusInfo,
+  dynamic messages
+}) {
+  return const TypeMatcher<ValidationResult>()
+      .having((ValidationResult result) => result.type, 'type', validationType)
+      .having((ValidationResult result) => result.statusInfo, 'statusInfo', statusInfo)
+      .having((ValidationResult result) => result.messages, 'messages', messages);
+}
+
 void main() {
   testWithoutContext('FlutterValidator shows an error message if gen_snapshot is '
     'downloaded and exits with code 1', () async {
@@ -48,7 +60,7 @@ void main() {
     fileSystem.file(artifacts.getArtifactPath(Artifact.genSnapshot)).createSync(recursive: true);
 
 
-    expect(await flutterValidator.validate(), matchDoctorValidation(
+    expect(await flutterValidator.validate(), _matchDoctorValidation(
       validationType: ValidationType.partial,
       statusInfo: 'Channel unknown, 1.0.0, on Linux, locale en_US.UTF-8',
       messages: containsAll(const <ValidationMessage>[
@@ -84,7 +96,7 @@ void main() {
 
     // gen_snapshot is downloaded on demand, and the doctor should not
     // fail if the gen_snapshot binary is not present.
-    expect(await flutterValidator.validate(), matchDoctorValidation(
+    expect(await flutterValidator.validate(), _matchDoctorValidation(
       validationType: ValidationType.installed,
       statusInfo: 'Channel unknown, 1.0.0, on Windows, locale en_US.UTF-8',
       messages: anything,
@@ -103,7 +115,7 @@ void main() {
       flutterRoot: () => 'sdk/flutter',
     );
 
-    expect(await flutterValidator.validate(), matchDoctorValidation(
+    expect(await flutterValidator.validate(), _matchDoctorValidation(
       validationType: ValidationType.partial,
       statusInfo: 'Channel unknown, 0.0.0, on Windows, locale en_US.UTF-8',
       messages: const <ValidationMessage>[
@@ -138,7 +150,7 @@ void main() {
       flutterRoot: () => 'sdk/flutter'
     );
 
-    expect(await flutterValidator.validate(), matchDoctorValidation(
+    expect(await flutterValidator.validate(), _matchDoctorValidation(
       validationType: ValidationType.installed,
       statusInfo: 'Channel unknown, 1.0.0, on Windows, locale en_US.UTF-8',
       messages: containsAll(const <ValidationMessage>[
diff --git a/packages/flutter_tools/test/general.shard/fuchsia/fuchsia_device_test.dart b/packages/flutter_tools/test/general.shard/fuchsia/fuchsia_device_test.dart
index 7616831628e..980bd5a5a9e 100644
--- a/packages/flutter_tools/test/general.shard/fuchsia/fuchsia_device_test.dart
+++ b/packages/flutter_tools/test/general.shard/fuchsia/fuchsia_device_test.dart
@@ -41,6 +41,7 @@ import 'package:vm_service/vm_service.dart' as vm_service;
 
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/fake_vm_services.dart';
 
 final vm_service.Isolate fakeIsolate = vm_service.Isolate(
   id: '1',
diff --git a/packages/flutter_tools/test/general.shard/hot_test.dart b/packages/flutter_tools/test/general.shard/hot_test.dart
index 230a9d82c79..541a19387a9 100644
--- a/packages/flutter_tools/test/general.shard/hot_test.dart
+++ b/packages/flutter_tools/test/general.shard/hot_test.dart
@@ -23,6 +23,7 @@ import 'package:mockito/mockito.dart';
 
 import '../src/common.dart';
 import '../src/context.dart';
+import '../src/fake_vm_services.dart';
 
 final vm_service.Isolate fakeUnpausedIsolate = vm_service.Isolate(
   id: '1',
diff --git a/packages/flutter_tools/test/general.shard/integration_test_device_test.dart b/packages/flutter_tools/test/general.shard/integration_test_device_test.dart
index 898e38d5b8b..7c393074d74 100644
--- a/packages/flutter_tools/test/general.shard/integration_test_device_test.dart
+++ b/packages/flutter_tools/test/general.shard/integration_test_device_test.dart
@@ -16,6 +16,7 @@ import 'package:vm_service/vm_service.dart' as vm_service;
 import '../src/common.dart';
 import '../src/context.dart';
 import '../src/fake_devices.dart';
+import '../src/fake_vm_services.dart';
 
 final Map<String, Object> vm = <String, dynamic>{
   'isolates': <dynamic>[
diff --git a/packages/flutter_tools/test/general.shard/ios/ios_device_logger_test.dart b/packages/flutter_tools/test/general.shard/ios/ios_device_logger_test.dart
index 0ed6a0269c9..8851843222e 100644
--- a/packages/flutter_tools/test/general.shard/ios/ios_device_logger_test.dart
+++ b/packages/flutter_tools/test/general.shard/ios/ios_device_logger_test.dart
@@ -21,6 +21,7 @@ import 'package:vm_service/vm_service.dart';
 
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/fake_vm_services.dart';
 
 void main() {
   FakeProcessManager processManager;
diff --git a/packages/flutter_tools/test/general.shard/resident_devtools_handler_test.dart b/packages/flutter_tools/test/general.shard/resident_devtools_handler_test.dart
index 19ed7b37ad5..e090f0d6de6 100644
--- a/packages/flutter_tools/test/general.shard/resident_devtools_handler_test.dart
+++ b/packages/flutter_tools/test/general.shard/resident_devtools_handler_test.dart
@@ -17,6 +17,7 @@ import 'package:test/fake.dart';
 
 import '../src/common.dart';
 import '../src/context.dart';
+import '../src/fake_vm_services.dart';
 
 final vm_service.Isolate isolate = vm_service.Isolate(
   id: '1',
diff --git a/packages/flutter_tools/test/general.shard/resident_runner_test.dart b/packages/flutter_tools/test/general.shard/resident_runner_test.dart
index 50be1f68850..64aaf80b0eb 100644
--- a/packages/flutter_tools/test/general.shard/resident_runner_test.dart
+++ b/packages/flutter_tools/test/general.shard/resident_runner_test.dart
@@ -40,6 +40,7 @@ import 'package:mockito/mockito.dart';
 
 import '../src/common.dart';
 import '../src/context.dart';
+import '../src/fake_vm_services.dart';
 import '../src/fakes.dart';
 import '../src/testbed.dart';
 
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 1bb58178d66..fbe5f5d0c00 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
@@ -34,6 +34,7 @@ import 'package:webkit_inspection_protocol/webkit_inspection_protocol.dart';
 
 import '../src/common.dart';
 import '../src/context.dart';
+import '../src/fake_vm_services.dart';
 import '../src/fakes.dart';
 
 const List<VmServiceExpectation> kAttachLogExpectations = <VmServiceExpectation>[
diff --git a/packages/flutter_tools/test/general.shard/runner/flutter_command_runner_test.dart b/packages/flutter_tools/test/general.shard/runner/flutter_command_runner_test.dart
index 155b8934ad2..7835cd0d370 100644
--- a/packages/flutter_tools/test/general.shard/runner/flutter_command_runner_test.dart
+++ b/packages/flutter_tools/test/general.shard/runner/flutter_command_runner_test.dart
@@ -20,6 +20,7 @@ import 'package:flutter_tools/src/version.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 import 'utils.dart';
 
 const String _kFlutterRoot = '/flutter/flutter';
diff --git a/packages/flutter_tools/test/general.shard/runner/flutter_command_test.dart b/packages/flutter_tools/test/general.shard/runner/flutter_command_test.dart
index cd36bbecff4..6bf75c90fe2 100644
--- a/packages/flutter_tools/test/general.shard/runner/flutter_command_test.dart
+++ b/packages/flutter_tools/test/general.shard/runner/flutter_command_test.dart
@@ -25,6 +25,7 @@ import 'package:mockito/mockito.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/test_flutter_command_runner.dart';
 import 'utils.dart';
 
 void main() {
diff --git a/packages/flutter_tools/test/general.shard/tracing_test.dart b/packages/flutter_tools/test/general.shard/tracing_test.dart
index a4d7857eb62..fa0804fee57 100644
--- a/packages/flutter_tools/test/general.shard/tracing_test.dart
+++ b/packages/flutter_tools/test/general.shard/tracing_test.dart
@@ -14,6 +14,7 @@ import 'package:flutter_tools/src/vmservice.dart';
 import 'package:vm_service/vm_service.dart' as vm_service;
 
 import '../src/common.dart';
+import '../src/fake_vm_services.dart';
 
 final vm_service.Isolate fakeUnpausedIsolate = vm_service.Isolate(
   id: '1',
diff --git a/packages/flutter_tools/test/general.shard/vmservice_test.dart b/packages/flutter_tools/test/general.shard/vmservice_test.dart
index 63a958954e1..a6d3733f0fe 100644
--- a/packages/flutter_tools/test/general.shard/vmservice_test.dart
+++ b/packages/flutter_tools/test/general.shard/vmservice_test.dart
@@ -19,6 +19,7 @@ import 'package:fake_async/fake_async.dart';
 
 import '../src/common.dart';
 import '../src/context.dart' hide testLogger;
+import '../src/fake_vm_services.dart';
 
 final Map<String, Object> vm = <String, dynamic>{
   'type': 'VM',
diff --git a/packages/flutter_tools/test/integration.shard/generated_plugin_registrant_test.dart b/packages/flutter_tools/test/integration.shard/generated_plugin_registrant_test.dart
index 67ca031128f..7fc9e2c35b9 100644
--- a/packages/flutter_tools/test/integration.shard/generated_plugin_registrant_test.dart
+++ b/packages/flutter_tools/test/integration.shard/generated_plugin_registrant_test.dart
@@ -18,6 +18,7 @@ import 'package:flutter_tools/src/globals.dart' as globals;
 
 import '../src/common.dart';
 import '../src/context.dart';
+import '../src/test_flutter_command_runner.dart';
 
 void main() {
   Directory tempDir;
diff --git a/packages/flutter_tools/test/src/common.dart b/packages/flutter_tools/test/src/common.dart
index f17a06cd79e..46bf41f06be 100644
--- a/packages/flutter_tools/test/src/common.dart
+++ b/packages/flutter_tools/test/src/common.dart
@@ -2,40 +2,22 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'dart:async';
 
-import 'package:args/args.dart';
-import 'package:args/command_runner.dart';
-import 'package:fake_async/fake_async.dart';
 import 'package:file/memory.dart';
 import 'package:flutter_tools/src/base/common.dart';
 import 'package:flutter_tools/src/base/context.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/io.dart';
-import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/base/platform.dart';
-import 'package:flutter_tools/src/base/user_messages.dart';
-import 'package:flutter_tools/src/cache.dart';
-import 'package:flutter_tools/src/commands/create.dart';
-import 'package:flutter_tools/src/convert.dart';
-import 'package:flutter_tools/src/doctor_validator.dart';
 import 'package:flutter_tools/src/globals_null_migrated.dart' as globals;
-import 'package:flutter_tools/src/runner/flutter_command.dart';
-import 'package:flutter_tools/src/runner/flutter_command_runner.dart';
-import 'package:flutter_tools/src/vmservice.dart';
 import 'package:meta/meta.dart';
 import 'package:path/path.dart' as path; // flutter_ignore: package_path_import
 import 'package:test_api/test_api.dart' as test_package show test; // ignore: deprecated_member_use
 import 'package:test_api/test_api.dart' hide test; // ignore: deprecated_member_use
-import 'package:vm_service/vm_service.dart' as vm_service;
 
 export 'package:test_api/test_api.dart' hide test, isInstanceOf; // ignore: deprecated_member_use
 
-/// A matcher that compares the type of the actual value to the type argument T.
-TypeMatcher<T> isInstanceOf<T>() => isA<T>();
-
 void tryToDelete(Directory directory) {
   // This should not be necessary, but it turns out that
   // on Windows it's common for deletions to fail due to
@@ -57,7 +39,7 @@ void tryToDelete(Directory directory) {
 String getFlutterRoot() {
   const Platform platform = LocalPlatform();
   if (platform.environment.containsKey('FLUTTER_ROOT')) {
-    return platform.environment['FLUTTER_ROOT'];
+    return platform.environment['FLUTTER_ROOT']!;
   }
 
   Error invalidScript() => StateError('Could not determine flutter_tools/ path from script URL (${globals.platform.script}); consider setting FLUTTER_ROOT explicitly.');
@@ -69,11 +51,11 @@ String getFlutterRoot() {
       break;
     case 'data':
       final RegExp flutterTools = RegExp(r'(file://[^"]*[/\\]flutter_tools[/\\][^"]+\.dart)', multiLine: true);
-      final Match match = flutterTools.firstMatch(Uri.decodeFull(platform.script.path));
+      final Match? match = flutterTools.firstMatch(Uri.decodeFull(platform.script.path));
       if (match == null) {
         throw invalidScript();
       }
-      scriptUri = Uri.parse(match.group(1));
+      scriptUri = Uri.parse(match.group(1)!);
       break;
     default:
       throw invalidScript();
@@ -88,23 +70,6 @@ String getFlutterRoot() {
   return path.normalize(path.join(toolsPath, '..', '..'));
 }
 
-/// Gets the path to the root of the Android SDK from the environment variable.
-String getAndroidSdkRoot() {
-  const Platform platform = LocalPlatform();
-  if (platform.environment.containsKey('ANDROID_SDK_ROOT')) {
-    return platform.environment['ANDROID_SDK_ROOT'];
-  }
-  throw StateError('ANDROID_SDK_ROOT environment varible not set');
-}
-
-CommandRunner<void> createTestCommandRunner([ FlutterCommand command ]) {
-  final FlutterCommandRunner runner = TestFlutterCommandRunner();
-  if (command != null) {
-    runner.addCommand(command);
-  }
-  return runner;
-}
-
 /// Capture console print events into a string buffer.
 Future<StringBuffer> capturedConsolePrint(Future<void> Function() body) async {
   final StringBuffer buffer = StringBuffer();
@@ -121,8 +86,8 @@ Future<StringBuffer> capturedConsolePrint(Future<void> Function() body) async {
 final Matcher throwsAssertionError = throwsA(isA<AssertionError>());
 
 /// Matcher for functions that throw [ToolExit].
-Matcher throwsToolExit({ int exitCode, Pattern message }) {
-  Matcher matcher = isToolExit;
+Matcher throwsToolExit({ int? exitCode, Pattern? message }) {
+  Matcher matcher = _isToolExit;
   if (exitCode != null) {
     matcher = allOf(matcher, (ToolExit e) => e.exitCode == exitCode);
   }
@@ -133,33 +98,19 @@ Matcher throwsToolExit({ int exitCode, Pattern message }) {
 }
 
 /// Matcher for [ToolExit]s.
-final TypeMatcher<ToolExit> isToolExit = isA<ToolExit>();
+final TypeMatcher<ToolExit> _isToolExit = isA<ToolExit>();
 
 /// Matcher for functions that throw [ProcessException].
-Matcher throwsProcessException({ Pattern message }) {
-  Matcher matcher = isProcessException;
+Matcher throwsProcessException({ Pattern? message }) {
+  Matcher matcher = _isProcessException;
   if (message != null) {
-    matcher = allOf(matcher, (ProcessException e) => e.message?.contains(message));
+    matcher = allOf(matcher, (ProcessException e) => e.message.contains(message));
   }
   return throwsA(matcher);
 }
 
 /// Matcher for [ProcessException]s.
-final TypeMatcher<ProcessException> isProcessException = isA<ProcessException>();
-
-/// Creates a flutter project in the [temp] directory using the
-/// [arguments] list if specified, or `--no-pub` if not.
-/// Returns the path to the flutter project.
-Future<String> createProject(Directory temp, { List<String> arguments }) async {
-  arguments ??= <String>['--no-pub'];
-  final String projectPath = globals.fs.path.join(temp.path, 'flutter_project');
-  final CreateCommand command = CreateCommand();
-  final CommandRunner<void> runner = createTestCommandRunner(command);
-  await runner.run(<String>['create', ...arguments, projectPath]);
-  // Created `.packages` since it's not created when the flag `--no-pub` is passed.
-  globals.fs.file(globals.fs.path.join(projectPath, '.packages')).createSync();
-  return projectPath;
-}
+final TypeMatcher<ProcessException> _isProcessException = isA<ProcessException>();
 
 Future<void> expectToolExitLater(Future<dynamic> future, Matcher messageMatcher) async {
   try {
@@ -187,12 +138,12 @@ Matcher containsIgnoringWhitespace(String toSearch) {
 /// `LocalFileSystem.dispose()`.
 @isTest
 void test(String description, FutureOr<void> Function() body, {
-  String testOn,
-  Timeout timeout,
+  String? testOn,
+  Timeout? timeout,
   dynamic skip,
-  List<String> tags,
-  Map<String, dynamic> onPlatform,
-  int retry,
+  List<String>? tags,
+  Map<String, dynamic>? onPlatform,
+  int? retry,
 }) {
   test_package.test(
     description,
@@ -221,17 +172,17 @@ void test(String description, FutureOr<void> Function() body, {
 /// For more information, see https://github.com/flutter/flutter/issues/47161
 @isTest
 void testWithoutContext(String description, FutureOr<void> Function() body, {
-  String testOn,
-  Timeout timeout,
+  String? testOn,
+  Timeout? timeout,
   dynamic skip,
-  List<String> tags,
-  Map<String, dynamic> onPlatform,
-  int retry,
+  List<String>? tags,
+  Map<String, dynamic>? onPlatform,
+  int? retry,
   }) {
   return test(
     description, () async {
       return runZoned(body, zoneValues: <Object, Object>{
-        contextKey: const NoContext(),
+        contextKey: const _NoContext(),
       });
     },
     timeout: timeout,
@@ -243,28 +194,13 @@ void testWithoutContext(String description, FutureOr<void> Function() body, {
   );
 }
 
-/// Runs a callback using FakeAsync.run while continually pumping the
-/// microtask queue. This avoids a deadlock when tests `await` a Future
-/// which queues a microtask that will not be processed unless the queue
-/// is flushed.
-Future<T> runFakeAsync<T>(Future<T> Function(FakeAsync time) f) async {
-  return FakeAsync().run((FakeAsync time) async {
-    bool pump = true;
-    final Future<T> future = f(time).whenComplete(() => pump = false);
-    while (pump) {
-      time.flushMicrotasks();
-    }
-    return future;
-  });
-}
-
 /// An implementation of [AppContext] that throws if context.get is called in the test.
 ///
 /// The intention of the class is to ensure we do not accidentally regress when
 /// moving towards more explicit dependency injection by accidentally using
 /// a Zone value in place of a constructor parameter.
-class NoContext implements AppContext {
-  const NoContext();
+class _NoContext implements AppContext {
+  const _NoContext();
 
   @override
   T get<T>() {
@@ -280,169 +216,16 @@ class NoContext implements AppContext {
 
   @override
   Future<V> run<V>({
-    FutureOr<V> Function() body,
-    String name,
-    Map<Type, Generator> overrides,
-    Map<Type, Generator> fallbacks,
-    ZoneSpecification zoneSpecification,
+    required FutureOr<V> Function() body,
+    String? name,
+    Map<Type, Generator>? overrides,
+    Map<Type, Generator>? fallbacks,
+    ZoneSpecification? zoneSpecification,
   }) async {
     return body();
   }
 }
 
-/// A fake implementation of a vm_service that mocks the JSON-RPC request
-/// and response structure.
-class FakeVmServiceHost {
-  FakeVmServiceHost({
-    @required List<VmServiceExpectation> requests,
-    Uri httpAddress,
-    Uri wsAddress,
-  }) : _requests = requests {
-    _vmService = FlutterVmService(vm_service.VmService(
-      _input.stream,
-      _output.add,
-    ), httpAddress: httpAddress, wsAddress: wsAddress);
-    _applyStreamListen();
-    _output.stream.listen((String data) {
-      final Map<String, Object> request = json.decode(data) as Map<String, Object>;
-      if (_requests.isEmpty) {
-        throw Exception('Unexpected request: $request');
-      }
-      final FakeVmServiceRequest fakeRequest = _requests.removeAt(0) as FakeVmServiceRequest;
-      expect(request, isA<Map<String, Object>>()
-        .having((Map<String, Object> request) => request['method'], 'method', fakeRequest.method)
-        .having((Map<String, Object> request) => request['params'], 'args', fakeRequest.args)
-      );
-      if (fakeRequest.close) {
-        unawaited(_vmService.dispose());
-        expect(_requests, isEmpty);
-        return;
-      }
-      if (fakeRequest.errorCode == null) {
-        _input.add(json.encode(<String, Object>{
-          'jsonrpc': '2.0',
-          'id': request['id'],
-          'result': fakeRequest.jsonResponse ?? <String, Object>{'type': 'Success'},
-        }));
-      } else {
-        _input.add(json.encode(<String, Object>{
-          'jsonrpc': '2.0',
-          'id': request['id'],
-          'error': <String, Object>{
-            'code': fakeRequest.errorCode,
-          }
-        }));
-      }
-      _applyStreamListen();
-    });
-  }
-
-  final List<VmServiceExpectation> _requests;
-  final StreamController<String> _input = StreamController<String>();
-  final StreamController<String> _output = StreamController<String>();
-
-  FlutterVmService get vmService => _vmService;
-  FlutterVmService _vmService;
-
-
-  bool get hasRemainingExpectations => _requests.isNotEmpty;
-
-  // remove FakeStreamResponse objects from _requests until it is empty
-  // or until we hit a FakeRequest
-  void _applyStreamListen() {
-    while (_requests.isNotEmpty && !_requests.first.isRequest) {
-      final FakeVmServiceStreamResponse response = _requests.removeAt(0) as FakeVmServiceStreamResponse;
-      _input.add(json.encode(<String, Object>{
-        'jsonrpc': '2.0',
-        'method': 'streamNotify',
-        'params': <String, Object>{
-          'streamId': response.streamId,
-          'event': response.event.toJson(),
-        },
-      }));
-    }
-  }
-}
-
-abstract class VmServiceExpectation {
-  bool get isRequest;
-}
-
-class FakeVmServiceRequest implements VmServiceExpectation {
-  const FakeVmServiceRequest({
-    @required this.method,
-    this.args = const <String, Object>{},
-    this.jsonResponse,
-    this.errorCode,
-    this.close = false,
-  });
-
-  final String method;
-
-  /// When true, the vm service is automatically closed.
-  final bool close;
-
-  /// If non-null, the error code for a [vm_service.RPCError] in place of a
-  /// standard response.
-  final int errorCode;
-  final Map<String, Object> args;
-  final Map<String, Object> jsonResponse;
-
-  @override
-  bool get isRequest => true;
-}
-
-class FakeVmServiceStreamResponse implements VmServiceExpectation {
-  const FakeVmServiceStreamResponse({
-    @required this.event,
-    @required this.streamId,
-  });
-
-  final vm_service.Event event;
-  final String streamId;
-
-  @override
-  bool get isRequest => false;
-}
-
-class TestFlutterCommandRunner extends FlutterCommandRunner {
-  @override
-  Future<void> runCommand(ArgResults topLevelResults) async {
-    final Logger topLevelLogger = globals.logger;
-    final Map<Type, dynamic> contextOverrides = <Type, dynamic>{
-      if (topLevelResults['verbose'] as bool)
-        Logger: VerboseLogger(topLevelLogger),
-    };
-    return context.run<void>(
-      overrides: contextOverrides.map<Type, Generator>((Type type, dynamic value) {
-        return MapEntry<Type, Generator>(type, () => value);
-      }),
-      body: () {
-        Cache.flutterRoot ??= Cache.defaultFlutterRoot(
-          platform: globals.platform,
-          fileSystem: globals.fs,
-          userMessages: UserMessages(),
-        );
-        // For compatibility with tests that set this to a relative path.
-        Cache.flutterRoot = globals.fs.path.normalize(globals.fs.path.absolute(Cache.flutterRoot));
-        return super.runCommand(topLevelResults);
-      }
-    );
-  }
-}
-
-/// Matches a doctor validation result.
-Matcher matchDoctorValidation({
-  ValidationType validationType,
-  String statusInfo,
-  dynamic messages
-}) {
-  return const TypeMatcher<ValidationResult>()
-    .having((ValidationResult result) => result.type, 'type', validationType)
-    .having((ValidationResult result) => result.statusInfo, 'statusInfo', statusInfo)
-    .having((ValidationResult result) => result.messages, 'messages', messages);
-}
-
 /// Allows inserting file system exceptions into certain
 /// [MemoryFileSystem] operations by tagging path/op combinations.
 ///
@@ -467,16 +250,16 @@ class FileExceptionHandler {
   void addError(FileSystemEntity entity, FileSystemOp operation, FileSystemException exception) {
     final String path = entity.path;
     _contextErrors[path] ??= <FileSystemOp, FileSystemException>{};
-    _contextErrors[path][operation] = exception;
+    _contextErrors[path]![operation] = exception;
   }
 
   // Tear-off this method and pass it to the memory filesystem `opHandle` parameter.
   void opHandle(String path, FileSystemOp operation) {
-    final Map<FileSystemOp, FileSystemException> exceptions = _contextErrors[path];
+    final Map<FileSystemOp, FileSystemException>? exceptions = _contextErrors[path];
     if (exceptions == null) {
       return;
     }
-    final FileSystemException exception = exceptions[operation];
+    final FileSystemException? exception = exceptions[operation];
     if (exception == null) {
       return;
     }
diff --git a/packages/flutter_tools/test/src/fake_vm_services.dart b/packages/flutter_tools/test/src/fake_vm_services.dart
new file mode 100644
index 00000000000..299f3e18a18
--- /dev/null
+++ b/packages/flutter_tools/test/src/fake_vm_services.dart
@@ -0,0 +1,131 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// @dart = 2.8
+
+import 'dart:async';
+
+import 'package:flutter_tools/src/base/common.dart';
+import 'package:flutter_tools/src/convert.dart';
+import 'package:flutter_tools/src/vmservice.dart';
+import 'package:meta/meta.dart';
+import 'package:test_api/test_api.dart' hide test; // ignore: deprecated_member_use
+import 'package:vm_service/vm_service.dart' as vm_service;
+
+export 'package:test_api/test_api.dart' hide test, isInstanceOf; // ignore: deprecated_member_use
+
+/// A fake implementation of a vm_service that mocks the JSON-RPC request
+/// and response structure.
+class FakeVmServiceHost {
+  FakeVmServiceHost({
+    @required List<VmServiceExpectation> requests,
+    Uri httpAddress,
+    Uri wsAddress,
+  }) : _requests = requests {
+    _vmService = FlutterVmService(vm_service.VmService(
+      _input.stream,
+      _output.add,
+    ), httpAddress: httpAddress, wsAddress: wsAddress);
+    _applyStreamListen();
+    _output.stream.listen((String data) {
+      final Map<String, Object> request = json.decode(data) as Map<String, Object>;
+      if (_requests.isEmpty) {
+        throw Exception('Unexpected request: $request');
+      }
+      final FakeVmServiceRequest fakeRequest = _requests.removeAt(0) as FakeVmServiceRequest;
+      expect(request, isA<Map<String, Object>>()
+        .having((Map<String, Object> request) => request['method'], 'method', fakeRequest.method)
+        .having((Map<String, Object> request) => request['params'], 'args', fakeRequest.args)
+      );
+      if (fakeRequest.close) {
+        unawaited(_vmService.dispose());
+        expect(_requests, isEmpty);
+        return;
+      }
+      if (fakeRequest.errorCode == null) {
+        _input.add(json.encode(<String, Object>{
+          'jsonrpc': '2.0',
+          'id': request['id'],
+          'result': fakeRequest.jsonResponse ?? <String, Object>{'type': 'Success'},
+        }));
+      } else {
+        _input.add(json.encode(<String, Object>{
+          'jsonrpc': '2.0',
+          'id': request['id'],
+          'error': <String, Object>{
+            'code': fakeRequest.errorCode,
+          }
+        }));
+      }
+      _applyStreamListen();
+    });
+  }
+
+  final List<VmServiceExpectation> _requests;
+  final StreamController<String> _input = StreamController<String>();
+  final StreamController<String> _output = StreamController<String>();
+
+  FlutterVmService get vmService => _vmService;
+  FlutterVmService _vmService;
+
+
+  bool get hasRemainingExpectations => _requests.isNotEmpty;
+
+  // remove FakeStreamResponse objects from _requests until it is empty
+  // or until we hit a FakeRequest
+  void _applyStreamListen() {
+    while (_requests.isNotEmpty && !_requests.first.isRequest) {
+      final FakeVmServiceStreamResponse response = _requests.removeAt(0) as FakeVmServiceStreamResponse;
+      _input.add(json.encode(<String, Object>{
+        'jsonrpc': '2.0',
+        'method': 'streamNotify',
+        'params': <String, Object>{
+          'streamId': response.streamId,
+          'event': response.event.toJson(),
+        },
+      }));
+    }
+  }
+}
+
+abstract class VmServiceExpectation {
+  bool get isRequest;
+}
+
+class FakeVmServiceRequest implements VmServiceExpectation {
+  const FakeVmServiceRequest({
+    @required this.method,
+    this.args = const <String, Object>{},
+    this.jsonResponse,
+    this.errorCode,
+    this.close = false,
+  });
+
+  final String method;
+
+  /// When true, the vm service is automatically closed.
+  final bool close;
+
+  /// If non-null, the error code for a [vm_service.RPCError] in place of a
+  /// standard response.
+  final int errorCode;
+  final Map<String, Object> args;
+  final Map<String, Object> jsonResponse;
+
+  @override
+  bool get isRequest => true;
+}
+
+class FakeVmServiceStreamResponse implements VmServiceExpectation {
+  const FakeVmServiceStreamResponse({
+    @required this.event,
+    @required this.streamId,
+  });
+
+  final vm_service.Event event;
+  final String streamId;
+
+  @override
+  bool get isRequest => false;
+}
diff --git a/packages/flutter_tools/test/src/test_flutter_command_runner.dart b/packages/flutter_tools/test/src/test_flutter_command_runner.dart
new file mode 100644
index 00000000000..3080377f3bc
--- /dev/null
+++ b/packages/flutter_tools/test/src/test_flutter_command_runner.dart
@@ -0,0 +1,69 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// @dart = 2.8
+
+import 'dart:async';
+
+import 'package:args/args.dart';
+import 'package:args/command_runner.dart';
+import 'package:flutter_tools/src/base/context.dart';
+import 'package:flutter_tools/src/base/file_system.dart';
+import 'package:flutter_tools/src/base/logger.dart';
+import 'package:flutter_tools/src/base/user_messages.dart';
+import 'package:flutter_tools/src/cache.dart';
+import 'package:flutter_tools/src/commands/create.dart';
+import 'package:flutter_tools/src/globals_null_migrated.dart' as globals;
+import 'package:flutter_tools/src/runner/flutter_command.dart';
+import 'package:flutter_tools/src/runner/flutter_command_runner.dart';
+
+export 'package:test_api/test_api.dart' hide test, isInstanceOf; // ignore: deprecated_member_use
+
+CommandRunner<void> createTestCommandRunner([ FlutterCommand command ]) {
+  final FlutterCommandRunner runner = TestFlutterCommandRunner();
+  if (command != null) {
+    runner.addCommand(command);
+  }
+  return runner;
+}
+
+/// Creates a flutter project in the [temp] directory using the
+/// [arguments] list if specified, or `--no-pub` if not.
+/// Returns the path to the flutter project.
+Future<String> createProject(Directory temp, { List<String> arguments }) async {
+  arguments ??= <String>['--no-pub'];
+  final String projectPath = globals.fs.path.join(temp.path, 'flutter_project');
+  final CreateCommand command = CreateCommand();
+  final CommandRunner<void> runner = createTestCommandRunner(command);
+  await runner.run(<String>['create', ...arguments, projectPath]);
+  // Created `.packages` since it's not created when the flag `--no-pub` is passed.
+  globals.fs.file(globals.fs.path.join(projectPath, '.packages')).createSync();
+  return projectPath;
+}
+
+class TestFlutterCommandRunner extends FlutterCommandRunner {
+  @override
+  Future<void> runCommand(ArgResults topLevelResults) async {
+    final Logger topLevelLogger = globals.logger;
+    final Map<Type, dynamic> contextOverrides = <Type, dynamic>{
+      if (topLevelResults['verbose'] as bool)
+        Logger: VerboseLogger(topLevelLogger),
+    };
+    return context.run<void>(
+      overrides: contextOverrides.map<Type, Generator>((Type type, dynamic value) {
+        return MapEntry<Type, Generator>(type, () => value);
+      }),
+      body: () {
+        Cache.flutterRoot ??= Cache.defaultFlutterRoot(
+          platform: globals.platform,
+          fileSystem: globals.fs,
+          userMessages: UserMessages(),
+        );
+        // For compatibility with tests that set this to a relative path.
+        Cache.flutterRoot = globals.fs.path.normalize(globals.fs.path.absolute(Cache.flutterRoot));
+        return super.runCommand(topLevelResults);
+      }
+    );
+  }
+}