Convert some general.shard base tests to null safety (#79985)

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

@@ -33,4 +33,4 @@ class ToolExit implements Exception {
 /// the flutter_tools package. However, there are times where one or more
 /// futures are intentionally not awaited. This function may be used to ignore a
 /// particular future. It silences the unawaited_futures lint.
-void unawaited(Future<void> future) { }
+void unawaited(Future<void>? future) { }

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

@@ -118,7 +118,7 @@ class AppContext {
     if (value == null && _parent != null) {
       value = _parent!.get<T>();
     }
-    return _unboxNull(value ?? _generateIfNecessary(T, _fallbacks)) as T;
+    return _unboxNull(value ?? _generateIfNecessary(T, _fallbacks)) as T?;
   }
 
   /// Runs [body] in a child context and returns the value returned by [body].

packages/flutter_tools/test/general.shard/base/async_guard_test.dart

@@ -2,7 +2,6 @@
 // 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';
 
@@ -32,7 +31,7 @@ Future<void> syncAndAsyncError() {
 Future<void> delayedThrow(FakeAsync time) {
   final Future<void> result =
     Future<void>.delayed(const Duration(milliseconds: 10))
-      .then((_) {
+      .then((_) async {
         throw 'Delayed Doom';
       });
   time.elapse(const Duration(seconds: 1));
@@ -41,10 +40,10 @@ Future<void> delayedThrow(FakeAsync time) {
 }
 
 void main() {
-  Completer<void> caughtInZone;
+  late Completer<void> caughtInZone;
   bool caughtByZone = false;
   bool caughtByHandler = false;
-  Zone zone;
+  late Zone zone;
 
   setUp(() {
     caughtInZone = Completer<void>();
@@ -270,7 +269,7 @@ void main() {
       unawaited(runZonedGuarded(() async {
         final Future<void> f = asyncGuard<void>(
           () => delayedThrow(time),
-          onError: (Object e, [StackTrace s]) {
+          onError: (Object e, [StackTrace? s]) {
             caughtByOnError = true;
             nonNullStackTrace = s != null;
           },

packages/flutter_tools/test/general.shard/base/common_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_tools/src/base/common.dart';
 import 'package:flutter_tools/src/base/context.dart';
 

packages/flutter_tools/test/general.shard/base/deferred_component_test.dart

@@ -2,19 +2,16 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:file/memory.dart';
 import 'package:flutter_tools/src/base/deferred_component.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/logger.dart';
 
 import '../../src/common.dart';
-import '../../src/context.dart';
 
 void main() {
   group('DeferredComponent basics', () {
-    test('constructor sets values', () {
+    testWithoutContext('constructor sets values', () {
       final DeferredComponent component = DeferredComponent(
         name: 'bestcomponent',
         libraries: <String>['lib1', 'lib2'],
@@ -25,7 +22,7 @@ void main() {
       expect(component.assets, <Uri>[Uri.file('asset1'), Uri.file('asset2')]);
     });
 
-    test('assignLoadingUnits selects the needed loading units and sets assigned', () {
+    testWithoutContext('assignLoadingUnits selects the needed loading units and sets assigned', () {
       final DeferredComponent component = DeferredComponent(
         name: 'bestcomponent',
         libraries: <String>['lib1', 'lib2'],
@@ -56,10 +53,10 @@ void main() {
       component.assignLoadingUnits(loadingUnits1);
 
       expect(component.assigned, true);
-      expect(component.loadingUnits.length, 2);
-      expect(component.loadingUnits.contains(loadingUnits1[0]), true);
-      expect(component.loadingUnits.contains(loadingUnits1[1]), true);
-      expect(component.loadingUnits.contains(loadingUnits1[2]), false);
+      expect(component.loadingUnits, hasLength(2));
+      expect(component.loadingUnits, contains(loadingUnits1[0]));
+      expect(component.loadingUnits, contains(loadingUnits1[1]));
+      expect(component.loadingUnits, isNot(contains(loadingUnits1[2])));
 
       final List<LoadingUnit> loadingUnits2 = <LoadingUnit>[
         LoadingUnit(
@@ -82,18 +79,18 @@ void main() {
       component.assignLoadingUnits(loadingUnits2);
 
       expect(component.assigned, true);
-      expect(component.loadingUnits.length, 1);
-      expect(component.loadingUnits.contains(loadingUnits2[0]), true);
-      expect(component.loadingUnits.contains(loadingUnits2[1]), false);
-      expect(component.loadingUnits.contains(loadingUnits2[2]), false);
+      expect(component.loadingUnits, hasLength(1));
+      expect(component.loadingUnits, contains(loadingUnits2[0]));
+      expect(component.loadingUnits, isNot(contains(loadingUnits2[1])));
+      expect(component.loadingUnits, isNot(contains(loadingUnits2[2])));
 
       component.assignLoadingUnits(<LoadingUnit>[]);
 
       expect(component.assigned, true);
-      expect(component.loadingUnits.length, 0);
+      expect(component.loadingUnits, hasLength(0));
     });
 
-    test('toString produces correct string for unassigned component', () {
+    testWithoutContext('toString produces correct string for unassigned component', () {
       final DeferredComponent component = DeferredComponent(
         name: 'bestcomponent',
         libraries: <String>['lib1', 'lib2'],
@@ -102,7 +99,7 @@ void main() {
       expect(component.toString(), '\nDeferredComponent: bestcomponent\n  Libraries:\n    - lib1\n    - lib2\n  Assets:\n    - asset1\n    - asset2');
     });
 
-    test('toString produces correct string for assigned component', () {
+    testWithoutContext('toString produces correct string for assigned component', () {
       final DeferredComponent component = DeferredComponent(
         name: 'bestcomponent',
         libraries: <String>['lib1', 'lib2'],
@@ -114,7 +111,7 @@ void main() {
   });
 
   group('LoadingUnit basics', () {
-    test('constructor sets values', () {
+    testWithoutContext('constructor sets values', () {
       final LoadingUnit unit = LoadingUnit(
         id: 2,
         path: 'path/to/so.so',
@@ -125,7 +122,7 @@ void main() {
       expect(unit.libraries, <String>['lib1', 'lib4']);
     });
 
-    test('toString produces correct string', () {
+    testWithoutContext('toString produces correct string', () {
       final LoadingUnit unit = LoadingUnit(
         id: 2,
         path: 'path/to/so.so',
@@ -134,7 +131,7 @@ void main() {
       expect(unit.toString(),'\nLoadingUnit 2\n  Libraries:\n  - lib1\n  - lib4');
     });
 
-    test('equalsIgnoringPath works for various input', () {
+    testWithoutContext('equalsIgnoringPath works for various input', () {
       final LoadingUnit unit1 = LoadingUnit(
         id: 2,
         path: 'path/to/so.so',
@@ -172,7 +169,7 @@ void main() {
       expect(unit5.equalsIgnoringPath(unit6), false);
     });
 
-    test('parseLoadingUnitManifest parses single manifest file', () {
+    testWithoutContext('parseLoadingUnitManifest parses single manifest file', () {
       final FileSystem fileSystem = MemoryFileSystem.test();
       final File manifest = fileSystem.file('/manifest.json');
       manifest.createSync(recursive: true);
@@ -202,7 +199,7 @@ void main() {
       expect(loadingUnits[1].libraries[1], 'lib4');
     });
 
-    testUsingContext('parseLoadingUnitManifest returns empty when manifest is invalid JSON', () {
+    testWithoutContext('parseLoadingUnitManifest returns empty when manifest is invalid JSON', () {
       final FileSystem fileSystem = MemoryFileSystem.test();
       final File manifest = fileSystem.file('/manifest.json');
       manifest.createSync(recursive: true);
@@ -225,7 +222,7 @@ void main() {
       expect(loadingUnits.isEmpty, true);
     });
 
-    testUsingContext('parseLoadingUnitManifest does not exist', () {
+    testWithoutContext('parseLoadingUnitManifest does not exist', () {
       final FileSystem fileSystem = MemoryFileSystem.test();
       final File manifest = fileSystem.file('/manifest.json');
       if (manifest.existsSync()) {
@@ -236,7 +233,7 @@ void main() {
       expect(loadingUnits.isEmpty, true);
     });
 
-    test('parseGeneratedLoadingUnits parses all abis if no abis provided', () {
+    testWithoutContext('parseGeneratedLoadingUnits parses all abis if no abis provided', () {
       final FileSystem fileSystem = MemoryFileSystem.test();
       final File manifest1 = fileSystem.file('/test-abi1/manifest.json');
       manifest1.createSync(recursive: true);
@@ -293,7 +290,7 @@ void main() {
       expect(loadingUnits[3].libraries[1], 'lib4');
     });
 
-    test('parseGeneratedLoadingUnits only parses provided abis', () {
+    testWithoutContext('parseGeneratedLoadingUnits only parses provided abis', () {
       final FileSystem fileSystem = MemoryFileSystem.test();
       final File manifest1 = fileSystem.file('/test-abi1/manifest.json');
       manifest1.createSync(recursive: true);
@@ -340,7 +337,7 @@ void main() {
       expect(loadingUnits[1].libraries[1], 'lib4');
     });
 
-    test('parseGeneratedLoadingUnits returns empty when no manifest files exist', () {
+    testWithoutContext('parseGeneratedLoadingUnits returns empty when no manifest files exist', () {
       final FileSystem fileSystem = MemoryFileSystem.test();
       final List<LoadingUnit> loadingUnits =
           LoadingUnit.parseGeneratedLoadingUnits(fileSystem.directory('/'), BufferLogger.test());

packages/flutter_tools/test/general.shard/base/file_system_test.dart

@@ -2,8 +2,6 @@
 // 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 'dart:io' as io;
 
@@ -15,12 +13,11 @@ import 'package:flutter_tools/src/base/signals.dart';
 import 'package:test/fake.dart';
 
 import '../../src/common.dart';
-import '../../src/context.dart';
 
 void main() {
   group('fsUtils', () {
-    MemoryFileSystem fs;
-    FileSystemUtils fsUtils;
+    late MemoryFileSystem fs;
+    late FileSystemUtils fsUtils;
 
     setUp(() {
       fs = MemoryFileSystem.test();
@@ -129,15 +126,15 @@ void main() {
   });
 
   group('LocalFileSystem', () {
-    FakeProcessSignal fakeSignal;
-    ProcessSignal signalUnderTest;
+    late FakeProcessSignal fakeSignal;
+    late ProcessSignal signalUnderTest;
 
     setUp(() {
       fakeSignal = FakeProcessSignal();
       signalUnderTest = ProcessSignal(fakeSignal);
     });
 
-    testUsingContext('deletes system temp entry on a fatal signal', () async {
+    testWithoutContext('deletes system temp entry on a fatal signal', () async {
       final Completer<void> completer = Completer<void>();
       final Signals signals = Signals.test();
       final LocalFileSystem localFileSystem = LocalFileSystem.test(

packages/flutter_tools/test/general.shard/base/fingerprint_test.dart

@@ -2,8 +2,6 @@
 // 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:convert' show json;
 
 import 'package:file/memory.dart';
@@ -12,9 +10,10 @@ import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/base/utils.dart';
 
 import '../../src/common.dart';
+
 void main() {
   group('Fingerprinter', () {
-    MemoryFileSystem fileSystem;
+    late MemoryFileSystem fileSystem;
 
     setUp(() {
       fileSystem = MemoryFileSystem.test();
@@ -85,7 +84,7 @@ void main() {
 
   group('Fingerprint', () {
     group('fromBuildInputs', () {
-      MemoryFileSystem fileSystem;
+      late MemoryFileSystem fileSystem;
 
       setUp(() {
         fileSystem = MemoryFileSystem.test();
@@ -104,8 +103,8 @@ void main() {
         fileSystem.file('b.dart').writeAsStringSync('This is b');
         final Fingerprint fingerprint = Fingerprint.fromBuildInputs(const <String>['a.dart', 'b.dart'], fileSystem);
 
-        final Map<String, dynamic> jsonObject = castStringKeyedMap(json.decode(fingerprint.toJson()));
-        expect(jsonObject['files'], hasLength(2));
+        final Map<String, dynamic>? jsonObject = castStringKeyedMap(json.decode(fingerprint.toJson()));
+        expect(jsonObject!['files'], hasLength(2));
         expect(jsonObject['files']['a.dart'], '8a21a15fad560b799f6731d436c1b698');
         expect(jsonObject['files']['b.dart'], '6f144e08b58cd0925328610fad7ac07c');
       });
@@ -124,9 +123,9 @@ void main() {
           },
         });
         final Fingerprint fingerprint = Fingerprint.fromJson(jsonString);
-        final Map<String, dynamic> content = castStringKeyedMap(json.decode(fingerprint.toJson()));
+        final Map<String, dynamic>? content = castStringKeyedMap(json.decode(fingerprint.toJson()));
         expect(content, hasLength(1));
-        expect(content['files'], hasLength(2));
+        expect(content!['files'], hasLength(2));
         expect(content['files']['a.dart'], '8a21a15fad560b799f6731d436c1b698');
         expect(content['files']['b.dart'], '6f144e08b58cd0925328610fad7ac07c');
       });

packages/flutter_tools/test/general.shard/base/io_test.dart

@@ -2,8 +2,6 @@
 // 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 'dart:io' as io;
 
@@ -13,11 +11,10 @@ import 'package:flutter_tools/src/base/platform.dart';
 import 'package:test/fake.dart';
 
 import '../../src/common.dart';
-import '../../src/context.dart';
 import '../../src/io.dart';
 
 void main() {
-  test('IOOverrides can inject a memory file system', () async {
+  testWithoutContext('IOOverrides can inject a memory file system', () async {
     final MemoryFileSystem memoryFileSystem = MemoryFileSystem.test();
     final FlutterIOOverrides flutterIOOverrides = FlutterIOOverrides(fileSystem: memoryFileSystem);
     await io.IOOverrides.runWithIOOverrides(() async {
@@ -57,7 +54,8 @@ void main() {
       expect(memoryFileSystem.link('ggg').resolveSymbolicLinksSync(), linkB.resolveSymbolicLinksSync());
     }, flutterIOOverrides);
   });
-  testUsingContext('ProcessSignal signals are properly delegated', () async {
+
+  testWithoutContext('ProcessSignal signals are properly delegated', () async {
     final FakeProcessSignal signal = FakeProcessSignal();
     final ProcessSignal signalUnderTest = ProcessSignal(signal);
 
@@ -66,15 +64,15 @@ void main() {
     expect(signalUnderTest, await signalUnderTest.watch().first);
   });
 
-  testUsingContext('ProcessSignal toString() works', () async {
+  testWithoutContext('ProcessSignal toString() works', () async {
     expect(io.ProcessSignal.sigint.toString(), ProcessSignal.sigint.toString());
   });
 
-  test('exit throws a StateError if called without being overriden', () {
+  testWithoutContext('exit throws a StateError if called without being overriden', () {
     expect(() => exit(0), throwsAssertionError);
   });
 
-  test('exit does not throw a StateError if overriden', () {
+  testWithoutContext('exit does not throw a StateError if overriden', () {
     try {
       setExitFunctionForTests((int value) {});
 
@@ -84,16 +82,16 @@ void main() {
     }
   });
 
-  test('test_api defines the Declarer in a known place', () {
+  testWithoutContext('test_api defines the Declarer in a known place', () {
     expect(Zone.current[#test.declarer], isNotNull);
   });
 
-  test('listNetworkInterfaces() uses overrides', () async {
+  testWithoutContext('listNetworkInterfaces() uses overrides', () async {
     setNetworkInterfaceLister(
       ({
-        bool includeLoopback,
-        bool includeLinkLocal,
-        InternetAddressType type,
+        bool? includeLoopback,
+        bool? includeLinkLocal,
+        InternetAddressType? type,
       }) async => <NetworkInterface>[],
     );
 

packages/flutter_tools/test/general.shard/base/net_test.dart

@@ -2,8 +2,6 @@
 // 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:convert';
 
 import 'package:file/file.dart';
@@ -20,7 +18,7 @@ import '../../src/common.dart';
 import '../../src/fake_http_client.dart';
 
 void main() {
-  BufferLogger testLogger;
+  late BufferLogger testLogger;
 
   setUp(() {
     testLogger = BufferLogger.test();
@@ -36,7 +34,7 @@ void main() {
 
   group('successful fetch', () {
     const String responseString = 'response string';
-    List<int> responseData;
+    late List<int> responseData;
 
     setUp(() {
       responseData = utf8.encode(responseString);
@@ -51,7 +49,7 @@ void main() {
         ])
       );
 
-      final List<int> data = await net.fetchUrl(Uri.parse('http://example.invalid/'));
+      final List<int>? data = await net.fetchUrl(Uri.parse('http://example.invalid/'));
       expect(data, equals(responseData));
     });
 
@@ -65,7 +63,7 @@ void main() {
       );
       final MemoryFileSystem fileSystem = MemoryFileSystem.test();
       final File destFile = fileSystem.file('dest_file')..createSync();
-      final List<int> data = await net.fetchUrl(
+      final List<int>? data = await net.fetchUrl(
         Uri.parse('http://example.invalid/'),
         destFile: destFile,
       );
@@ -127,9 +125,9 @@ void main() {
         FakeRequest(invalid, responseError: const io.SocketException('')),
       ])
     );
-    String error;
+    String? error;
     FakeAsync().run((FakeAsync time) {
-      net.fetchUrl(invalid).then((List<int> value) {
+      net.fetchUrl(invalid).then((List<int>? value) async {
         error = 'test completed unexpectedly';
       }, onError: (dynamic exception) {
         error = 'test failed unexpectedly: $exception';
@@ -158,9 +156,9 @@ void main() {
         FakeRequest(invalid, responseError: const io.HandshakeException('')),
       ])
     );
-    String error;
+    String? error;
     FakeAsync().run((FakeAsync time) {
-      net.fetchUrl(invalid).then((List<int> value) {
+      net.fetchUrl(invalid).then((List<int>? value) async {
         error = 'test completed unexpectedly';
       }, onError: (dynamic exception) {
         error = 'test failed: $exception';
@@ -188,9 +186,9 @@ void main() {
         },
       ),
     );
-    String error;
+    String? error;
     FakeAsync().run((FakeAsync time) {
-      net.fetchUrl(Uri.parse('example.invalid/')).then((List<int> value) {
+      net.fetchUrl(Uri.parse('example.invalid/')).then((List<int>? value) async {
         error = 'test completed unexpectedly';
       }, onError: (dynamic exception) {
         error = 'test failed: $exception';
@@ -214,9 +212,9 @@ void main() {
         FakeRequest(invalid, responseError: const io.HttpException('')),
       ])
     );
-    String error;
+    String? error;
     FakeAsync().run((FakeAsync time) {
-      net.fetchUrl(invalid).then((List<int> value) {
+      net.fetchUrl(invalid).then((List<int>? value) async {
         error = 'test completed unexpectedly';
       }, onError: (dynamic exception) {
         error = 'test failed unexpectedly: $exception';
@@ -245,9 +243,9 @@ void main() {
         FakeRequest(invalid, responseError: const io.HttpException('')),
       ])
     );
-    String error;
+    String? error;
     FakeAsync().run((FakeAsync time) {
-      net.fetchUrl(invalid).then((List<int> value) {
+      net.fetchUrl(invalid).then((List<int>? value) async {
         error = 'test completed unexpectedly';
       }, onError: (dynamic exception) {
         error = 'test failed unexpectedly: $exception';
@@ -281,10 +279,10 @@ void main() {
         )),
       ])
     );
-    String error;
-    List<int> actualResult;
+    String? error;
+    List<int>? actualResult;
     FakeAsync().run((FakeAsync time) {
-      net.fetchUrl(invalid, maxAttempts: 3).then((List<int> value) {
+      net.fetchUrl(invalid, maxAttempts: 3).then((List<int>? value) async {
         actualResult = value;
       }, onError: (dynamic exception) {
         error = 'test failed unexpectedly: $exception';

packages/flutter_tools/test/general.shard/base/os_test.dart

@@ -13,7 +13,7 @@ import 'package:flutter_tools/src/base/os.dart';
 import 'package:flutter_tools/src/base/platform.dart';
 
 import '../../src/common.dart';
-import '../../src/context.dart';
+import '../../src/fake_process_manager.dart';
 
 const String kExecutable = 'foo';
 const String kPath1 = '/bar/bin/$kExecutable';

packages/flutter_tools/test/general.shard/base/os_utils_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/base/os.dart';
@@ -15,8 +13,8 @@ import '../../src/common.dart';
 
 void main() {
   group('OperatingSystemUtils', () {
-    Directory tempDir;
-    FileSystem fileSystem;
+    late Directory tempDir;
+    late FileSystem fileSystem;
 
     setUp(() {
       fileSystem = LocalFileSystem.test(signals: Signals.test());

packages/flutter_tools/test/general.shard/base/platform_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_tools/src/base/platform.dart';
 
 import '../../src/common.dart';
@@ -26,8 +24,8 @@ void _expectPlatformsEqual(Platform actual, Platform expected) {
 
 void main() {
   group('FakePlatform.fromPlatform', () {
-    FakePlatform fake;
-    LocalPlatform local;
+    late FakePlatform fake;
+    late LocalPlatform local;
 
     setUp(() {
       local = const LocalPlatform();

packages/flutter_tools/test/general.shard/base/signals_test.dart

@@ -2,8 +2,6 @@
 // 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 'dart:io' as io;
 
@@ -15,9 +13,9 @@ import '../../src/common.dart';
 
 void main() {
   group('Signals', () {
-    Signals signals;
-    FakeProcessSignal fakeSignal;
-    ProcessSignal signalUnderTest;
+    late Signals signals;
+    late FakeProcessSignal fakeSignal;
+    late ProcessSignal signalUnderTest;
 
     setUp(() {
       signals = Signals.test();
@@ -58,7 +56,7 @@ void main() {
 
     testWithoutContext('signal handlers do not cause concurrent modification errors when removing handlers in a signal callback', () async {
       final Completer<void> completer = Completer<void>();
-      Object token;
+      late Object token;
       Future<void> handle(ProcessSignal s) async {
         expect(s, signalUnderTest);
         expect(await signals.removeHandler(signalUnderTest, token), true);
@@ -73,7 +71,7 @@ void main() {
 
     testWithoutContext('signal handler error goes on error stream', () async {
       final Exception exn = Exception('Error');
-      signals.addHandler(signalUnderTest, (ProcessSignal s) {
+      signals.addHandler(signalUnderTest, (ProcessSignal s) async {
         throw exn;
       });
 
@@ -95,7 +93,7 @@ void main() {
     testWithoutContext('removed signal handler does not run', () async {
       final Object token = signals.addHandler(
         signalUnderTest,
-        (ProcessSignal s) {
+        (ProcessSignal s) async {
           fail('Signal handler should have been removed.');
         },
       );
@@ -124,7 +122,7 @@ void main() {
 
       final Object token = signals.addHandler(
         signalUnderTest,
-        (ProcessSignal s) {
+        (ProcessSignal s) async {
           fail('Signal handler should have been removed.');
         },
       );
@@ -153,7 +151,7 @@ void main() {
         completer.complete();
       });
 
-      signals.addHandler(otherSignal, (ProcessSignal s) {
+      signals.addHandler(otherSignal, (ProcessSignal s) async {
         fail('Wrong signal!.');
       });
 

packages/flutter_tools/test/general.shard/base/terminal_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_tools/src/base/io.dart';
 import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/base/platform.dart';
@@ -37,7 +35,7 @@ void main() {
   });
 
   group('ANSI coloring and bold', () {
-    AnsiTerminal terminal;
+    late AnsiTerminal terminal;
 
     setUp(() {
       terminal = AnsiTerminal(
@@ -108,7 +106,7 @@ void main() {
   });
 
   group('character input prompt', () {
-    AnsiTerminal terminalUnderTest;
+    late AnsiTerminal terminalUnderTest;
 
     setUp(() {
       terminalUnderTest = TestTerminal(stdio: FakeStdio());
@@ -118,7 +116,7 @@ void main() {
       expect(terminalUnderTest.promptForCharInput(
         <String>['a', 'b', 'c'],
         prompt: 'Please choose something',
-        logger: null,
+        logger: BufferLogger.test(),
       ), throwsStateError);
     });
 
@@ -183,13 +181,13 @@ void main() {
   });
 }
 
-Stream<String> mockStdInStream;
+late Stream<String> mockStdInStream;
 
 class TestTerminal extends AnsiTerminal {
   TestTerminal({
-    Stdio stdio,
+    Stdio? stdio,
     Platform platform = const LocalPlatform(),
-  }) : super(stdio: stdio, platform: platform);
+  }) : super(stdio: stdio ?? Stdio(), platform: platform);
 
   @override
   Stream<String> get keystrokes {

packages/flutter_tools/test/general.shard/base/user_messages_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_tools/src/base/platform.dart';
 import 'package:flutter_tools/src/base/user_messages.dart';
 

packages/flutter_tools/test/general.shard/build_system/hash_test.dart

@@ -2,8 +2,6 @@
 // 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:convert';
 import 'dart:typed_data';