diff --git a/packages/flutter_tools/test/integration.shard/analyze_once_test.dart b/packages/flutter_tools/test/integration.shard/analyze_once_test.dart
index c679cffd9b..d27868ce91 100644
--- a/packages/flutter_tools/test/integration.shard/analyze_once_test.dart
+++ b/packages/flutter_tools/test/integration.shard/analyze_once_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/io.dart';
 import '../src/common.dart';
@@ -12,12 +10,12 @@ import 'test_utils.dart';
 final String analyzerSeparator = platform.isWindows ? '-' : '•';
 
 void main() {
-  Directory tempDir;
-  String projectPath;
-  File libMain;
+  late Directory tempDir;
+  late String projectPath;
+  late File libMain;
 
   Future<void> runCommand({
-    List<String> arguments,
+    List<String> arguments = const <String>[],
     List<String> statusTextContains = const <String>[],
     List<String> errorTextContains = const <String>[],
     String exitMessageContains = '',
diff --git a/packages/flutter_tools/test/integration.shard/analyze_size_test.dart b/packages/flutter_tools/test/integration.shard/analyze_size_test.dart
index 1fe91a542a..949bf6fe30 100644
--- a/packages/flutter_tools/test/integration.shard/analyze_size_test.dart
+++ b/packages/flutter_tools/test/integration.shard/analyze_size_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:file/file.dart';
 import 'package:file_testing/file_testing.dart';
 import 'package:flutter_tools/src/base/io.dart';
diff --git a/packages/flutter_tools/test/integration.shard/android_plugin_example_app_build_test.dart b/packages/flutter_tools/test/integration.shard/android_plugin_example_app_build_test.dart
index d7da32183c..86ffbd3b8a 100644
--- a/packages/flutter_tools/test/integration.shard/android_plugin_example_app_build_test.dart
+++ b/packages/flutter_tools/test/integration.shard/android_plugin_example_app_build_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:file_testing/file_testing.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 
@@ -11,7 +9,7 @@ import '../src/common.dart';
 import 'test_utils.dart';
 
 void main() {
-  Directory tempDir;
+  late Directory tempDir;
 
   setUp(() async {
     tempDir = createResolvedTempDirectorySync('flutter_plugin_test.');
diff --git a/packages/flutter_tools/test/integration.shard/background_isolate_test.dart b/packages/flutter_tools/test/integration.shard/background_isolate_test.dart
index bc1cb9a67f..193f1bbff0 100644
--- a/packages/flutter_tools/test/integration.shard/background_isolate_test.dart
+++ b/packages/flutter_tools/test/integration.shard/background_isolate_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 'package:file/file.dart';
@@ -14,7 +12,7 @@ import 'test_driver.dart';
 import 'test_utils.dart';
 
 void main() {
-  Directory tempDir;
+  late Directory tempDir;
 
   setUp(() async {
     tempDir = createResolvedTempDirectorySync('hot_reload_test.');
@@ -56,7 +54,7 @@ void main() {
     // Wait a tiny amount of time in case we did not kill the background isolate.
     await Future<void>.delayed(const Duration(milliseconds: 10));
     await subscription.cancel();
-    await flutter?.stop();
+    await flutter.stop();
   });
 
   testWithoutContext('Hot reload updates background isolates', () async {
@@ -84,6 +82,6 @@ void main() {
     await flutter.hotReload();
     await sawNewBackgroundMessage.future;
     await subscription.cancel();
-    await flutter?.stop();
+    await flutter.stop();
   });
 }
diff --git a/packages/flutter_tools/test/integration.shard/build_ios_config_only_test.dart b/packages/flutter_tools/test/integration.shard/build_ios_config_only_test.dart
index f5adc08a02..63d1abfe57 100644
--- a/packages/flutter_tools/test/integration.shard/build_ios_config_only_test.dart
+++ b/packages/flutter_tools/test/integration.shard/build_ios_config_only_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:file_testing/file_testing.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/io.dart';
diff --git a/packages/flutter_tools/test/integration.shard/command_output_test.dart b/packages/flutter_tools/test/integration.shard/command_output_test.dart
index e1fa2197b8..0023ce8753 100644
--- a/packages/flutter_tools/test/integration.shard/command_output_test.dart
+++ b/packages/flutter_tools/test/integration.shard/command_output_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:flutter_tools/src/base/file_system.dart';
@@ -138,11 +136,11 @@ void main() {
       '--machine',
     ]);
 
-    final Map<String, Object> versionInfo = json.decode(result.stdout
+    final Map<String, Object?> versionInfo = json.decode(result.stdout
       .toString()
       .replaceAll('Building flutter tool...', '')
       .replaceAll('Waiting for another flutter command to release the startup lock...', '')
-      .trim()) as Map<String, Object>;
+      .trim()) as Map<String, Object?>;
 
     expect(versionInfo, containsPair('flutterRoot', isNotNull));
   });
diff --git a/packages/flutter_tools/test/integration.shard/coverage_collection_test.dart b/packages/flutter_tools/test/integration.shard/coverage_collection_test.dart
index d6bbe45e68..22a52a3a01 100644
--- a/packages/flutter_tools/test/integration.shard/coverage_collection_test.dart
+++ b/packages/flutter_tools/test/integration.shard/coverage_collection_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:file/file.dart';
 import 'package:file_testing/file_testing.dart';
 
@@ -14,7 +12,7 @@ import 'test_driver.dart';
 import 'test_utils.dart';
 
 void main() {
-  Directory tempDir;
+  late Directory tempDir;
 
   setUp(() async {
     tempDir = createResolvedTempDirectorySync('flutter_coverage_collection_test.');
diff --git a/packages/flutter_tools/test/integration.shard/debugger_stepping_test.dart b/packages/flutter_tools/test/integration.shard/debugger_stepping_test.dart
index a6f96d925d..2b259c2b70 100644
--- a/packages/flutter_tools/test/integration.shard/debugger_stepping_test.dart
+++ b/packages/flutter_tools/test/integration.shard/debugger_stepping_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:file/file.dart';
 
 import '../src/common.dart';
@@ -12,7 +10,7 @@ import 'test_driver.dart';
 import 'test_utils.dart';
 
 void main() {
-  Directory tempDir;
+  late Directory tempDir;
 
   setUp(() async {
     tempDir = createResolvedTempDirectorySync('debugger_stepping_test.');
@@ -32,13 +30,13 @@ void main() {
     await _flutter.addBreakpoint(_project.breakpointUri, _project.breakpointLine);
     await _flutter.resume(waitForNextPause: true); // Now we should be on the breakpoint.
 
-    expect((await _flutter.getSourceLocation()).line, equals(_project.breakpointLine));
+    expect((await _flutter.getSourceLocation())?.line, equals(_project.breakpointLine));
 
     // Issue 5 steps, ensuring that we end up on the annotated lines each time.
     for (int i = 1; i <= _project.numberOfSteps; i += 1) {
       await _flutter.stepOverOrOverAsyncSuspension();
-      final SourcePosition location = await _flutter.getSourceLocation();
-      final int actualLine = location.line;
+      final SourcePosition? location = await _flutter.getSourceLocation();
+      final int? actualLine = location?.line;
 
       // Get the line we're expected to stop at by searching for the comment
       // within the source code.