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 2c070a600a..f71c824017 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
@@ -29,6 +29,7 @@ import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fake_pub_deps.dart';
 import '../../src/fakes.dart';
+import '../../src/package_config.dart';
 import '../../src/test_build_system.dart';
 import '../../src/test_flutter_command_runner.dart';
 
@@ -86,8 +87,8 @@ void main() {
 
   // Sets up the minimal mock project files necessary to look like a Flutter project.
   void createCoreMockProjectFiles() {
-    fileSystem.file('pubspec.yaml').createSync();
-    fileSystem.directory('.dart_tool').childFile('package_config.json').createSync(recursive: true);
+    fileSystem.file('pubspec.yaml').writeAsStringSync('name: my_app');
+    writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
     fileSystem.file(fileSystem.path.join('lib', 'main.dart')).createSync(recursive: true);
   }
 
@@ -258,10 +259,7 @@ void main() {
         osUtils: FakeOperatingSystemUtils(),
       );
       fileSystem.file('pubspec.yaml').createSync();
-      fileSystem
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
+      writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
       fileSystem.file(fileSystem.path.join('lib', 'main.dart')).createSync(recursive: true);
 
       final bool supported =
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 a1624d61e5..01574bd24f 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
@@ -26,6 +26,7 @@ import '../../src/context.dart';
 import '../../src/fake_process_manager.dart';
 import '../../src/fake_pub_deps.dart';
 import '../../src/fakes.dart';
+import '../../src/package_config.dart';
 import '../../src/test_build_system.dart';
 import '../../src/test_flutter_command_runner.dart';
 
@@ -93,8 +94,8 @@ void main() {
 
   // Sets up the minimal mock project files necessary to look like a Flutter project.
   void createCoreMockProjectFiles() {
-    fileSystem.file('pubspec.yaml').createSync();
-    fileSystem.directory('.dart_tool').childFile('package_config.json').createSync(recursive: true);
+    fileSystem.file('pubspec.yaml').writeAsStringSync('name: my_app');
+    writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
     fileSystem.file(fileSystem.path.join('lib', 'main.dart')).createSync(recursive: true);
   }
 
@@ -287,10 +288,7 @@ void main() {
         osUtils: FakeOperatingSystemUtils(),
       );
       fileSystem.file('pubspec.yaml').createSync();
-      fileSystem
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
+      writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
       fileSystem.file(fileSystem.path.join('lib', 'main.dart')).createSync(recursive: true);
 
       final bool supported =
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 0d5a130c55..4accd0d3d8 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:unified_analytics/unified_analytics.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/package_config.dart';
 import '../../src/test_build_system.dart';
 import '../../src/test_flutter_command_runner.dart';
 
@@ -60,7 +61,7 @@ void main() {
   // Creates the mock files necessary to look like a Flutter project.
   void setUpMockCoreProjectFiles() {
     fileSystem.file('pubspec.yaml').createSync();
-    fileSystem.directory('.dart_tool').childFile('package_config.json').createSync(recursive: true);
+    writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
     fileSystem.file(fileSystem.path.join('lib', 'main.dart')).createSync(recursive: true);
   }
 
@@ -685,10 +686,7 @@ project(runner LANGUAGES CXX)
 set(BINARY_NAME "fizz_bar")
 ''');
       fileSystem.file('pubspec.yaml').createSync();
-      fileSystem
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
+      writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
       final FlutterProject flutterProject = FlutterProject.fromDirectoryTest(
         fileSystem.currentDirectory,
       );
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 2802a2b791..7d9db7d0ac 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
@@ -27,6 +27,7 @@ import '../../src/context.dart';
 import '../../src/fake_process_manager.dart';
 import '../../src/fake_pub_deps.dart';
 import '../../src/fakes.dart';
+import '../../src/package_config.dart';
 import '../../src/test_build_system.dart';
 import '../../src/test_flutter_command_runner.dart';
 
@@ -75,8 +76,9 @@ void main() {
 
   // Sets up the minimal mock project files necessary to look like a Flutter project.
   void createCoreMockProjectFiles() {
-    fileSystem.file('pubspec.yaml').createSync();
-    fileSystem.file('.dart_tool/package_config.json').createSync(recursive: true);
+    fileSystem.file('pubspec.yaml').writeAsStringSync('name: my_app');
+    writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
+
     fileSystem.file(fileSystem.path.join('lib', 'main.dart')).createSync(recursive: true);
   }
 
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 2ab0988736..6b2c933f10 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
@@ -20,6 +20,7 @@ import 'package:flutter_tools/src/web/compile.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/package_config.dart';
 import '../../src/test_build_system.dart';
 import '../../src/test_flutter_command_runner.dart';
 
@@ -39,7 +40,7 @@ void main() {
     fileSystem.file('pubspec.yaml')
       ..createSync()
       ..writeAsStringSync('name: foo\n');
-    fileSystem.directory('.dart_tool').childFile('package_config.json').createSync(recursive: true);
+    writePackageConfigFile(mainLibName: 'foo', directory: fileSystem.currentDirectory);
     fileSystem.file(fileSystem.path.join('web', 'index.html')).createSync(recursive: true);
     fileSystem.file(fileSystem.path.join('lib', 'main.dart')).createSync(recursive: true);
     logger = BufferLogger.test();
@@ -505,27 +506,11 @@ void setupFileSystemForEndToEndTest(FileSystem fileSystem) {
   }
 
   // Project files.
-  fileSystem.directory('.dart_tool').childFile('package_config.json')
-    ..createSync(recursive: true)
-    ..writeAsStringSync('''
-{
-  "packages": [
-    {
-      "name": "foo",
-      "rootUri": "../",
-      "packageUri": "lib/",
-      "languageVersion": "3.2"
-    },
-    {
-      "name": "fizz",
-      "rootUri": "../bar",
-      "packageUri": "lib/",
-      "languageVersion": "3.2"
-    }
-  ],
-  "configVersion": 2
-}
-''');
+  writePackageConfigFile(
+    directory: fileSystem.currentDirectory,
+    mainLibName: 'foo',
+    packages: <String, String>{'fizz': 'bar'},
+  );
   fileSystem.file('pubspec.yaml').writeAsStringSync('''
 name: foo
 
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 cae29287ce..363b02d214 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
@@ -19,6 +19,7 @@ import 'package:unified_analytics/unified_analytics.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/package_config.dart';
 import '../../src/test_flutter_command_runner.dart';
 
 const String flutterRoot = r'C:\flutter';
@@ -62,7 +63,7 @@ void main() {
   // Creates the mock files necessary to look like a Flutter project.
   void setUpMockCoreProjectFiles() {
     fileSystem.file('pubspec.yaml').createSync();
-    fileSystem.directory('.dart_tool').childFile('package_config.json').createSync(recursive: true);
+    writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
     fileSystem.file(fileSystem.path.join('lib', 'main.dart')).createSync(recursive: true);
   }
 
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/clean_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/clean_test.dart
index fd7d835e23..a45c1d58f0 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/clean_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/clean_test.dart
@@ -19,6 +19,7 @@ import 'package:test/fake.dart';
 
 import '../../src/common.dart';
 import '../../src/context.dart';
+import '../../src/package_config.dart';
 import '../../src/test_flutter_command_runner.dart';
 
 void main() {
@@ -273,10 +274,8 @@ FlutterProject setupProjectUnderTest(Directory currentDirectory, bool setupXcode
         .createSync(recursive: true);
   }
   projectUnderTest.dartTool.createSync(recursive: true);
-  projectUnderTest.directory
-      .childDirectory('.dart_tool')
-      .childFile('package_config.jon')
-      .createSync(recursive: true);
+  writePackageConfigFile(directory: projectUnderTest.directory, mainLibName: 'my_app');
+
   projectUnderTest.android.ephemeralDirectory.createSync(recursive: true);
 
   projectUnderTest.ios.ephemeralDirectory.createSync(recursive: true);
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 670dee308f..3d6395e441 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
@@ -19,6 +19,7 @@ import 'package:test/fake.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/package_config.dart';
 import '../../src/test_flutter_command_runner.dart';
 import '../../src/testbed.dart';
 
@@ -39,10 +40,7 @@ class FakePub extends Fake implements Pub {
     bool shouldSkipThirdPartyGenerator = true,
     PubOutputMode outputMode = PubOutputMode.all,
   }) async {
-    project.directory
-        .childDirectory('.dart_tool')
-        .childFile('package_config.json')
-        .createSync(recursive: true);
+    writePackageConfigFile(directory: project.directory, mainLibName: 'my_app');
     if (offline) {
       calledGetOffline += 1;
     } else {
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/pub_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/pub_test.dart
index 477c7cebf3..d648c0e6d3 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/pub_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/pub_test.dart
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:convert';
+
 import 'package:args/command_runner.dart';
 import 'package:file/memory.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
@@ -18,6 +20,7 @@ import 'package:unified_analytics/unified_analytics.dart';
 import '../../src/context.dart';
 import '../../src/fake_pub_deps.dart';
 import '../../src/fakes.dart';
+import '../../src/package_config.dart';
 import '../../src/test_flutter_command_runner.dart';
 
 const String minimalV2EmbeddingManifest = r'''
@@ -48,7 +51,7 @@ void main() {
   setUp(() {
     Cache.disableLocking();
     fileSystem = MemoryFileSystem.test();
-    pub = FakePub(fileSystem);
+    pub = FakePub();
     logger = BufferLogger.test();
   });
 
@@ -73,7 +76,7 @@ void main() {
   testUsingContext(
     'pub get usage values are resilient to missing package config files before running "pub get"',
     () async {
-      fileSystem.currentDirectory.childFile('pubspec.yaml').createSync();
+      fileSystem.currentDirectory.childFile('pubspec.yaml').writeAsStringSync('name: my_app');
       fileSystem.currentDirectory.childFile('.flutter-plugins').createSync();
       fileSystem.currentDirectory.childFile('.flutter-plugins-dependencies').createSync();
       fileSystem.currentDirectory.childDirectory('android').childFile('AndroidManifest.xml')
@@ -152,8 +155,19 @@ void main() {
       await commandRunner.run(<String>['get', '--directory=${targetDirectory.path}']);
       final FlutterProject rootProject = FlutterProject.fromDirectory(targetDirectory);
       final File packageConfigFile = rootProject.dartTool.childFile('package_config.json');
+
       expect(packageConfigFile.existsSync(), true);
-      expect(packageConfigFile.readAsStringSync(), '{"configVersion":2,"packages":[]}');
+      expect(json.decode(packageConfigFile.readAsStringSync()), <String, Object>{
+        'configVersion': 2,
+        'packages': <Object?>[
+          <String, Object?>{
+            'name': 'my_app',
+            'rootUri': '../',
+            'packageUri': 'lib/',
+            'languageVersion': '3.7',
+          },
+        ],
+      });
     },
     overrides: <Type, Generator>{
       Pub: () => pub,
@@ -328,9 +342,8 @@ void main() {
 }
 
 class FakePub extends Fake implements Pub {
-  FakePub(this.fileSystem);
+  FakePub();
 
-  final FileSystem fileSystem;
   List<String>? expectedArguments;
 
   @override
@@ -347,12 +360,7 @@ class FakePub extends Fake implements Pub {
       expect(arguments, expectedArguments);
     }
     if (project != null) {
-      fileSystem
-          .directory(project.directory)
-          .childDirectory('.dart_tool')
-          .childFile('package_config.json')
-        ..createSync(recursive: true)
-        ..writeAsStringSync('{"configVersion":2,"packages":[]}');
+      writePackageConfigFile(directory: project.directory, mainLibName: 'my_app');
     }
   }
 
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 eff680ba97..7841c03abb 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/run_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/run_test.dart
@@ -35,6 +35,7 @@ import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fake_devices.dart';
 import '../../src/fakes.dart';
+import '../../src/package_config.dart';
 import '../../src/test_flutter_command_runner.dart';
 
 void main() {
@@ -174,15 +175,9 @@ void main() {
         artifacts = Artifacts.test();
         fs = MemoryFileSystem.test();
 
-        fs.currentDirectory.childFile('pubspec.yaml').writeAsStringSync('name: flutter_app');
-        fs.currentDirectory.childDirectory('.dart_tool').childFile('package_config.json')
-          ..createSync(recursive: true)
-          ..writeAsStringSync('''
-{
-  "packages": [],
-  "configVersion": 2
-}
-''');
+        fs.currentDirectory.childFile('pubspec.yaml').writeAsStringSync('name: my_app');
+        writePackageConfigFile(directory: fs.currentDirectory, mainLibName: 'my_app');
+
         final Directory libDir = fs.currentDirectory.childDirectory('lib');
         libDir.createSync();
         final File mainFile = libDir.childFile('main.dart');
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 ca84eaac9b..175ed0d31f 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/test_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/test_test.dart
@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 import 'dart:async';
-import 'dart:convert';
 
 import 'package:args/command_runner.dart';
 import 'package:file/memory.dart';
@@ -37,66 +36,16 @@ import '../../src/context.dart';
 import '../../src/fake_devices.dart';
 import '../../src/fake_vm_services.dart';
 import '../../src/logging_logger.dart';
+import '../../src/package_config.dart';
 import '../../src/test_flutter_command_runner.dart';
 
-final String _flutterToolsPackageConfigContents = json.encode(<String, Object>{
-  'configVersion': 2,
-  'packages': <Map<String, Object>>[
-    <String, String>{
-      'name': 'ffi',
-      'rootUri': 'file:///path/to/pubcache/.pub-cache/hosted/pub.dev/ffi-2.1.2',
-      'packageUri': 'lib/',
-      'languageVersion': '3.3',
-    },
-    <String, String>{
-      'name': 'test',
-      'rootUri': 'file:///path/to/pubcache/.pub-cache/hosted/pub.dev/test-1.24.9',
-      'packageUri': 'lib/',
-      'languageVersion': '3.0',
-    },
-    <String, String>{
-      'name': 'test_api',
-      'rootUri': 'file:///path/to/pubcache/.pub-cache/hosted/pub.dev/test_api-0.6.1',
-      'packageUri': 'lib/',
-      'languageVersion': '3.0',
-    },
-    <String, String>{
-      'name': 'test_core',
-      'rootUri': 'file:///path/to/pubcache/.pub-cache/hosted/pub.dev/test_core-0.5.9',
-      'packageUri': 'lib/',
-      'languageVersion': '3.0',
-    },
-  ],
-  'generated': '2021-02-24T07:55:20.084834Z',
-  'generator': 'pub',
-  'generatorVersion': '2.13.0-68.0.dev',
-});
 const String _pubspecContents = '''
+name: my_app
 dev_dependencies:
   flutter_test:
     sdk: flutter
   integration_test:
     sdk: flutter''';
-final String _packageConfigContents = json.encode(<String, Object>{
-  'configVersion': 2,
-  'packages': <Map<String, Object>>[
-    <String, String>{
-      'name': 'test_api',
-      'rootUri': 'file:///path/to/pubcache/.pub-cache/hosted/pub.dartlang.org/test_api-0.2.19',
-      'packageUri': 'lib/',
-      'languageVersion': '2.12',
-    },
-    <String, String>{
-      'name': 'integration_test',
-      'rootUri': 'file:///path/to/flutter/packages/integration_test',
-      'packageUri': 'lib/',
-      'languageVersion': '2.12',
-    },
-  ],
-  'generated': '2021-02-24T07:55:20.084834Z',
-  'generator': 'pub',
-  'generatorVersion': '2.13.0-68.0.dev',
-});
 
 void main() {
   Cache.disableLocking();
@@ -111,20 +60,30 @@ void main() {
     final Directory package = fs.directory('package');
     package.childFile('pubspec.yaml').createSync(recursive: true);
     package.childFile('pubspec.yaml').writeAsStringSync(_pubspecContents);
-    (package.childDirectory('.dart_tool').childFile('package_config.json')
-      ..createSync(recursive: true)).writeAsStringSync(_packageConfigContents);
+    writePackageConfigFile(
+      directory: package,
+      packages: <String, String>{
+        'test_api': 'file:///path/to/pubcache/.pub-cache/hosted/pub.dartlang.org/test_api-0.2.19',
+        'integration_test': 'file:///path/to/flutter/packages/integration_test',
+      },
+      mainLibName: 'my_app',
+    );
     package.childDirectory('test').childFile('some_test.dart').createSync(recursive: true);
     package
         .childDirectory('integration_test')
         .childFile('some_integration_test.dart')
         .createSync(recursive: true);
 
-    final File flutterToolsPackageConfigFile = fs
-        .directory(fs.path.join(getFlutterRoot(), 'packages', 'flutter_tools'))
-        .childDirectory('.dart_tool')
-        .childFile('package_config.json');
-    flutterToolsPackageConfigFile.createSync(recursive: true);
-    flutterToolsPackageConfigFile.writeAsStringSync(_flutterToolsPackageConfigContents);
+    writePackageConfigFile(
+      directory: fs.directory(fs.path.join(getFlutterRoot(), 'packages', 'flutter_tools')),
+      packages: <String, String>{
+        'ffi': 'file:///path/to/pubcache/.pub-cache/hosted/pub.dev/ffi-2.1.2',
+        'test': 'file:///path/to/pubcache/.pub-cache/hosted/pub.dev/test-1.24.9',
+        'test_api': 'file:///path/to/pubcache/.pub-cache/hosted/pub.dev/test_api-0.6.1',
+        'test_core': 'file:///path/to/pubcache/.pub-cache/hosted/pub.dev/test_core-0.5.9',
+      },
+      mainLibName: 'my_app',
+    );
 
     fs.currentDirectory = package.path;
 
@@ -161,26 +120,14 @@ dev_dependencies:
   flutter_test:
     sdk: flutter
     ''');
-      fs
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .writeAsStringSync(
-            json.encode(<String, Object>{
-              'configVersion': 2,
-              'packages': <Map<String, Object>>[
-                <String, String>{
-                  'name': 'test_api',
-                  'rootUri':
-                      'file:///path/to/pubcache/.pub-cache/hosted/pub.dartlang.org/test_api-0.2.19',
-                  'packageUri': 'lib/',
-                  'languageVersion': '2.12',
-                },
-              ],
-              'generated': '2021-02-24T07:55:20.084834Z',
-              'generator': 'pub',
-              'generatorVersion': '2.13.0-68.0.dev',
-            }),
-          );
+      writePackageConfigFile(
+        directory: fs.currentDirectory,
+        packages: <String, String>{
+          'test_api': 'file:///path/to/pubcache/.pub-cache/hosted/pub.dartlang.org/test_api-0.2.19',
+        },
+        mainLibName: 'my_app',
+      );
+
       final FakePackageTest fakePackageTest = FakePackageTest();
       final TestCommand testCommand = TestCommand(testWrapper: fakePackageTest);
       final CommandRunner<void> commandRunner = createTestCommandRunner(testCommand);
@@ -361,7 +308,7 @@ dev_dependencies:
   testUsingContext(
     'Coverage provides current library name to Coverage Collector by default',
     () async {
-      const String currentPackageName = '';
+      const String currentPackageName = 'my_app';
       final FakeVmServiceHost fakeVmServiceHost = FakeVmServiceHost(
         requests: <VmServiceExpectation>[
           FakeVmServiceRequest(
@@ -1210,6 +1157,7 @@ const List<String> packageTestArgs = <String>[
       fs.file('vanilla.txt').writeAsStringSync('vanilla');
       fs.file('orange.txt').writeAsStringSync('orange');
       fs.file('pubspec.yaml').writeAsStringSync('''
+name: my_app
 flutter:
   assets:
     - path: vanilla.txt
@@ -1251,6 +1199,7 @@ dev_dependencies:
       fs.file('vanilla.txt').writeAsStringSync('vanilla');
       fs.file('flavorless.txt').writeAsStringSync('flavorless');
       fs.file('pubspec.yaml').writeAsStringSync('''
+name: my_app
 flutter:
   assets:
     - path: vanilla.txt
@@ -1321,6 +1270,7 @@ dev_dependencies:
       final FakeFlutterTestRunner testRunner = FakeFlutterTestRunner(0);
       fs.file('asset.txt').writeAsStringSync('1');
       fs.file('pubspec.yaml').writeAsStringSync('''
+name: my_app
 flutter:
   assets:
     - asset.txt
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/update_packages_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/update_packages_test.dart
index d410aec0ad..65ef2440f4 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/update_packages_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/update_packages_test.dart
@@ -14,6 +14,7 @@ import 'package:test/fake.dart';
 import 'package:yaml/yaml.dart';
 
 import '../../src/context.dart';
+import '../../src/package_config.dart';
 import '../../src/test_flutter_command_runner.dart';
 
 // An example pubspec.yaml from flutter, not necessary for it to be up to date.
@@ -116,7 +117,7 @@ void main() {
         ..writeAsStringSync(kExamplesPubspecYaml);
       flutter.childFile('pubspec.yaml').writeAsStringSync(kFlutterPubspecYaml);
       Cache.flutterRoot = flutterSdk.absolute.path;
-      pub = FakePub(fileSystem);
+      pub = FakePub();
       processManager = FakeProcessManager.empty();
     });
 
@@ -367,9 +368,8 @@ void main() {
 }
 
 class FakePub extends Fake implements Pub {
-  FakePub(this.fileSystem);
+  FakePub();
 
-  final FileSystem fileSystem;
   final List<String> pubGetDirectories = <String>[];
   final List<String> pubBatchDirectories = <String>[];
   final List<String> pubspecYamls = <String>[];
@@ -405,9 +405,7 @@ packages:
 sdks:
   dart: ">=2.14.0 <3.0.0"
 ''');
-    fileSystem.currentDirectory.childDirectory('.dart_tool').childFile('package_config.json')
-      ..createSync(recursive: true)
-      ..writeAsStringSync('{"configVersion":2,"packages":[]}');
+    writePackageConfigFile(directory: project.directory, mainLibName: 'my_app');
   }
 
   @override
diff --git a/packages/flutter_tools/test/commands.shard/hermetic/widget_preview/widget_preview_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/widget_preview/widget_preview_test.dart
index df56562bdb..ab539cb703 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/widget_preview/widget_preview_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/widget_preview/widget_preview_test.dart
@@ -19,6 +19,7 @@ import 'package:test_api/fake.dart';
 import '../../../src/common.dart';
 import '../../../src/context.dart';
 import '../../../src/fakes.dart';
+import '../../../src/package_config.dart';
 
 void main() {
   group('WidgetPreviewStartCommand', () {
@@ -174,19 +175,6 @@ flutter:
                 - deferredComponentArg
         - path: package/deferredComponentUri''';
 
-  static const String basicPackageConfig = '''
-{
-  "configVersion": 2,
-  "packages": [
-    {
-      "name": "test",
-      "rootUri": "fileSystem.currentDirectory.path",
-      "packageUri": "lib/"
-    }
-  ]
-}
-''';
-
   final String projectRoot;
   final FileSystem fileSystem;
   final Logger logger;
@@ -212,10 +200,9 @@ flutter:
 
   @override
   late final File packageConfig = () {
-    final File file = fileSystem
-      .directory(fileSystem.path.join(projectRoot, '.dart_tool'))
-      .childFile('package_config.json')..createSync(recursive: true);
-    file.writeAsStringSync(basicPackageConfig);
-    return file;
+    return writePackageConfigFile(
+      directory: fileSystem.directory(projectRoot),
+      mainLibName: 'my_app',
+    );
   }();
 }
diff --git a/packages/flutter_tools/test/general.shard/application_package_test.dart b/packages/flutter_tools/test/general.shard/application_package_test.dart
index f8d845914c..8bec511c01 100644
--- a/packages/flutter_tools/test/general.shard/application_package_test.dart
+++ b/packages/flutter_tools/test/general.shard/application_package_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/package_config.dart';
 
 void main() {
   group('Apk with partial Android SDK works', () {
@@ -982,9 +983,7 @@ class FakeAndroidSdkVersion extends Fake implements AndroidSdkVersion {
 
 Future<FlutterProject> aModuleProject() async {
   final Directory directory = globals.fs.directory('module_project');
-  directory.childDirectory('.dart_tool').childFile('package_config.json')
-    ..createSync(recursive: true)
-    ..writeAsStringSync('{"configVersion":2,"packages":[]}');
+  writePackageConfigFile(directory: directory, mainLibName: 'my_app');
   directory.childFile('pubspec.yaml').writeAsStringSync('''
 name: my_module
 flutter:
diff --git a/packages/flutter_tools/test/general.shard/asset_bundle_flavors_test.dart b/packages/flutter_tools/test/general.shard/asset_bundle_flavors_test.dart
index 123ceee620..62e23ec802 100644
--- a/packages/flutter_tools/test/general.shard/asset_bundle_flavors_test.dart
+++ b/packages/flutter_tools/test/general.shard/asset_bundle_flavors_test.dart
@@ -12,6 +12,7 @@ import 'package:flutter_tools/src/cache.dart';
 import 'package:flutter_tools/src/project.dart';
 
 import '../src/common.dart';
+import '../src/package_config.dart';
 
 void main() {
   Future<ManifestAssetBundle> buildBundleWithFlavor(
@@ -50,10 +51,8 @@ void main() {
       final BufferLogger logger = BufferLogger.test();
       final FakePlatform platform = FakePlatform();
 
-      fileSystem
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
+      writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'example');
+
       fileSystem
           .file(fileSystem.path.join('assets', 'common', 'image.png'))
           .createSync(recursive: true);
@@ -129,10 +128,8 @@ flutter:
       );
       final BufferLogger logger = BufferLogger.test();
       final FakePlatform platform = FakePlatform();
-      fileSystem
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
+      writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'example');
+
       fileSystem.file(fileSystem.path.join('assets', 'unflavored.png')).createSync(recursive: true);
       fileSystem
           .file(fileSystem.path.join('assets', 'vanillaOrange.png'))
@@ -174,10 +171,7 @@ flutter:
       );
       final BufferLogger logger = BufferLogger.test();
       final FakePlatform platform = FakePlatform();
-      fileSystem
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
+      writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'example');
       fileSystem.file(fileSystem.path.join('vanilla', 'vanilla.png')).createSync(recursive: true);
       fileSystem
           .file(fileSystem.path.join('vanilla', 'flavorless.png'))
@@ -217,10 +211,7 @@ flutter:
       );
       final BufferLogger logger = BufferLogger.test();
       final FakePlatform platform = FakePlatform();
-      fileSystem
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
+      writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'example');
       fileSystem.file('orange.png').createSync(recursive: true);
       fileSystem.file('pubspec.yaml')
         ..createSync()
@@ -258,10 +249,7 @@ flutter:
       );
       final BufferLogger logger = BufferLogger.test();
       final FakePlatform platform = FakePlatform();
-      fileSystem
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
+      writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'example');
       fileSystem
           .file(fileSystem.path.join('vanilla', 'actually-strawberry.png'))
           .createSync(recursive: true);
diff --git a/packages/flutter_tools/test/general.shard/asset_bundle_package_fonts_test.dart b/packages/flutter_tools/test/general.shard/asset_bundle_package_fonts_test.dart
index c587186117..1647585e35 100644
--- a/packages/flutter_tools/test/general.shard/asset_bundle_package_fonts_test.dart
+++ b/packages/flutter_tools/test/general.shard/asset_bundle_package_fonts_test.dart
@@ -14,6 +14,7 @@ import 'package:flutter_tools/src/globals.dart' as globals;
 
 import '../src/common.dart';
 import '../src/context.dart';
+import '../src/package_config.dart';
 
 void main() {
   String fixPath(String path) {
@@ -47,26 +48,6 @@ $fontsSection
 ''');
   }
 
-  void writePackageConfigFile(Map<String, String> packages) {
-    globals.fs.directory('.dart_tool').childFile('package_config.json')
-      ..createSync(recursive: true)
-      ..writeAsStringSync(
-        json.encode(<String, dynamic>{
-          'packages': <dynamic>[
-            ...packages.entries.map((MapEntry<String, String> entry) {
-              return <String, dynamic>{
-                'name': entry.key,
-                'rootUri': '../${entry.value}',
-                'packageUri': 'lib/',
-                'languageVersion': '3.2',
-              };
-            }),
-          ],
-          'configVersion': 2,
-        }),
-      );
-  }
-
   Future<void> buildAndVerifyFonts(
     List<String> localFonts,
     List<String> packageFonts,
@@ -116,8 +97,13 @@ $fontsSection
     testUsingContext(
       'App includes neither font manifest nor fonts when no defines fonts',
       () async {
+        final Map<String, String> deps = <String, String>{'test_package': 'p/p/'};
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          packages: deps,
+          mainLibName: 'my_app',
+        );
         writePubspecFile('p/p/pubspec.yaml', 'test_package');
 
         final AssetBundle bundle = AssetBundleFactory.instance.createBundle();
@@ -146,8 +132,14 @@ $fontsSection
          fonts:
            - asset: packages/test_package/bar
 ''';
-        writePubspecFile('pubspec.yaml', 'test', fontsSection: fontsSection);
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePubspecFile('pubspec.yaml', 'my_app', fontsSection: fontsSection);
+
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+
+          packages: <String, String>{'test_package': 'p/p/'},
+          mainLibName: 'my_app',
+        );
         writePubspecFile('p/p/pubspec.yaml', 'test_package');
 
         const String font = 'bar';
@@ -177,8 +169,13 @@ $fontsSection
            - asset: packages/test_package/bar
            - asset: a/bar
 ''';
-        writePubspecFile('pubspec.yaml', 'test', fontsSection: fontsSection);
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePubspecFile('pubspec.yaml', 'my_app', fontsSection: fontsSection);
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+
+          packages: <String, String>{'test_package': 'p/p/'},
+          mainLibName: 'my_app',
+        );
         writePubspecFile('p/p/pubspec.yaml', 'test_package');
 
         const String packageFont = 'bar';
@@ -202,8 +199,14 @@ $fontsSection
     testUsingContext(
       'App uses package font with own font file',
       () async {
+        final Map<String, String> deps = <String, String>{'test_package': 'p/p/'};
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+
+          packages: deps,
+          mainLibName: 'my_app',
+        );
         const String fontsSection = '''
        - family: foo
          fonts:
@@ -233,8 +236,17 @@ $fontsSection
     testUsingContext(
       'App uses package font with font file from another package',
       () async {
+        final Map<String, String> deps = <String, String>{
+          'test_package': 'p/p/',
+          'test_package2': 'p2/p/',
+        };
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/', 'test_package2': 'p2/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+
+          packages: deps,
+          mainLibName: 'test',
+        );
         const String fontsSection = '''
        - family: foo
          fonts:
@@ -265,8 +277,14 @@ $fontsSection
     testUsingContext(
       'App uses package font with properties and own font file',
       () async {
+        final Map<String, String> deps = <String, String>{'test_package': 'p/p/'};
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+
+          packages: deps,
+          mainLibName: 'my_app',
+        );
 
         const String pubspec = '''
        - family: foo
@@ -298,13 +316,19 @@ $fontsSection
     testUsingContext(
       'App uses local font and package font with own font file.',
       () async {
+        final Map<String, String> deps = <String, String>{'test_package': 'p/p/'};
         const String fontsSection = '''
        - family: foo
          fonts:
            - asset: a/bar
 ''';
         writePubspecFile('pubspec.yaml', 'test', fontsSection: fontsSection);
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          packages: deps,
+          mainLibName: 'test',
+        );
+
         writePubspecFile('p/p/pubspec.yaml', 'test_package', fontsSection: fontsSection);
 
         const String font = 'a/bar';
diff --git a/packages/flutter_tools/test/general.shard/asset_bundle_package_test.dart b/packages/flutter_tools/test/general.shard/asset_bundle_package_test.dart
index 79820e62ba..b015bb200b 100644
--- a/packages/flutter_tools/test/general.shard/asset_bundle_package_test.dart
+++ b/packages/flutter_tools/test/general.shard/asset_bundle_package_test.dart
@@ -16,6 +16,7 @@ import 'package:standard_message_codec/standard_message_codec.dart';
 
 import '../src/common.dart';
 import '../src/context.dart';
+import '../src/package_config.dart';
 
 void main() {
   String fixPath(String path) {
@@ -71,26 +72,6 @@ $assetsSection
 ''');
   }
 
-  void writePackageConfigFile(Map<String, String> packages) {
-    globals.fs.directory('.dart_tool').childFile('package_config.json')
-      ..createSync(recursive: true)
-      ..writeAsStringSync(
-        json.encode(<String, dynamic>{
-          'packages': <dynamic>[
-            ...packages.entries.map((MapEntry<String, String> entry) {
-              return <String, dynamic>{
-                'name': entry.key,
-                'rootUri': '../${entry.value}',
-                'packageUri': 'lib/',
-                'languageVersion': '3.2',
-              };
-            }),
-          ],
-          'configVersion': 2,
-        }),
-      );
-  }
-
   Map<Object, Object> assetManifestBinToJson(Map<Object, Object> manifest) {
     List<Object> convertList(List<Object> variants) =>
         variants.map((Object variant) => (variant as Map<Object?, Object?>)['asset']!).toList();
@@ -159,7 +140,11 @@ $assetsSection
       'No assets are bundled when the package has no assets',
       () async {
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          packages: <String, String>{'test_package': 'p/p/'},
+          mainLibName: 'my_app',
+        );
         writePubspecFile('p/p/pubspec.yaml', 'test_package');
 
         final AssetBundle bundle = AssetBundleFactory.instance.createBundle();
@@ -190,7 +175,11 @@ $assetsSection
       'No assets are bundled when the package has an asset that is not listed',
       () async {
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          packages: <String, String>{'test_package': 'p/p/'},
+          mainLibName: 'my_app',
+        );
         writePubspecFile('p/p/pubspec.yaml', 'test_package');
 
         final List<String> assets = <String>['a/foo'];
@@ -225,7 +214,11 @@ $assetsSection
       'asset its pubspec',
       () async {
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          packages: <String, String>{'test_package': 'p/p/'},
+          mainLibName: 'my_app',
+        );
 
         final List<String> assets = <String>['a/foo'];
         writePubspecFile('p/p/pubspec.yaml', 'test_package', assets: assets);
@@ -252,7 +245,11 @@ $assetsSection
       () async {
         final List<String> assetEntries = <String>['packages/test_package/a/foo'];
         writePubspecFile('pubspec.yaml', 'test', assets: assetEntries);
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          packages: <String, String>{'test_package': 'p/p/'},
+          mainLibName: 'my_app',
+        );
         writePubspecFile('p/p/pubspec.yaml', 'test_package');
 
         final List<String> assets = <String>['a/foo'];
@@ -276,7 +273,11 @@ $assetsSection
       'has an asset and a variant, and lists the asset in its pubspec',
       () async {
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          packages: <String, String>{'test_package': 'p/p/'},
+          mainLibName: 'my_app',
+        );
         writePubspecFile('p/p/pubspec.yaml', 'test_package', assets: <String>['a/foo', 'a/bar']);
 
         final List<String> assets = <String>['a/foo', 'a/2x/foo', 'a/bar'];
@@ -305,7 +306,11 @@ $assetsSection
       'has an asset and a variant, and the app lists the asset in its pubspec',
       () async {
         writePubspecFile('pubspec.yaml', 'test', assets: <String>['packages/test_package/a/foo']);
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'test_package': 'p/p/'},
+        );
         writePubspecFile('p/p/pubspec.yaml', 'test_package');
 
         final List<String> assets = <String>['a/foo', 'a/2x/foo'];
@@ -331,7 +336,11 @@ $assetsSection
       'two assets in its pubspec',
       () async {
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'test_package': 'p/p/'},
+        );
 
         final List<String> assets = <String>['a/foo', 'a/bar'];
         writePubspecFile('p/p/pubspec.yaml', 'test_package', assets: assets);
@@ -362,7 +371,11 @@ $assetsSection
           'packages/test_package/a/bar',
         ];
         writePubspecFile('pubspec.yaml', 'test', assets: assetEntries);
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'test_package': 'p/p/'},
+        );
 
         final List<String> assets = <String>['a/foo', 'a/bar'];
         writePubspecFile('p/p/pubspec.yaml', 'test_package');
@@ -389,7 +402,11 @@ $assetsSection
       'Two assets are bundled when two packages each have and list an asset their pubspec',
       () async {
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/', 'test_package2': 'p2/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'test_package': 'p/p/', 'test_package2': 'p2/p/'},
+        );
         writePubspecFile('p/p/pubspec.yaml', 'test_package', assets: <String>['a/foo']);
         writePubspecFile('p2/p/pubspec.yaml', 'test_package2', assets: <String>['a/foo']);
 
@@ -427,7 +444,11 @@ $assetsSection
           'packages/test_package2/a/foo',
         ];
         writePubspecFile('pubspec.yaml', 'test', assets: assetEntries);
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/', 'test_package2': 'p2/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'test_package': 'p/p/', 'test_package2': 'p2/p/'},
+        );
         writePubspecFile('p/p/pubspec.yaml', 'test_package');
         writePubspecFile('p2/p/pubspec.yaml', 'test_package2');
 
@@ -462,7 +483,11 @@ $assetsSection
       'listing in its pubspec an asset from another package',
       () async {
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/', 'test_package2': 'p2/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'test_package': 'p/p/', 'test_package2': 'p2/p/'},
+        );
         writePubspecFile(
           'p/p/pubspec.yaml',
           'test_package',
@@ -492,7 +517,11 @@ $assetsSection
       'Flavored assets are bundled when the app depends on a package',
       () async {
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'test_package': 'p/p/'},
+        );
         writePubspecFile(
           'p/p/pubspec.yaml',
           'test_package',
@@ -526,7 +555,11 @@ $assetsSection
     'Asset paths can contain URL reserved characters',
     () async {
       writePubspecFile('pubspec.yaml', 'test');
-      writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+      writePackageConfigFile(
+        directory: globals.fs.currentDirectory,
+        mainLibName: 'my_app',
+        packages: <String, String>{'test_package': 'p/p/'},
+      );
 
       final List<String> assets = <String>['a/foo', 'a/foo [x]'];
       writePubspecFile('p/p/pubspec.yaml', 'test_package', assets: assets);
@@ -553,7 +586,11 @@ $assetsSection
     'Asset paths can contain URL reserved characters',
     () async {
       writePubspecFile('pubspec.yaml', 'test');
-      writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+      writePackageConfigFile(
+        directory: globals.fs.currentDirectory,
+        mainLibName: 'my_app',
+        packages: <String, String>{'test_package': 'p/p/'},
+      );
 
       final List<String> assets = <String>['a/foo', 'a/foo [x]'];
       writePubspecFile('p/p/pubspec.yaml', 'test_package', assets: assets);
@@ -581,7 +618,11 @@ $assetsSection
       'Two assets are bundled when scanning their directory',
       () async {
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'test_package': 'p/p/'},
+        );
 
         final List<String> assetsOnDisk = <String>['a/foo', 'a/bar'];
         final List<String> assetsOnManifest = <String>['a/'];
@@ -610,7 +651,11 @@ $assetsSection
       'Two assets are bundled when listing one and scanning second directory',
       () async {
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'test_package': 'p/p/'},
+        );
 
         final List<String> assetsOnDisk = <String>['a/foo', 'abc/bar'];
         final List<String> assetOnManifest = <String>['a/foo', 'abc/'];
@@ -639,7 +684,11 @@ $assetsSection
       'One asset is bundled with variant, scanning wrong directory',
       () async {
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'test_package': 'p/p/'},
+        );
 
         final List<String> assetsOnDisk = <String>['a/foo', 'a/b/foo', 'a/bar'];
         final List<String> assetOnManifest = <String>[
@@ -672,7 +721,11 @@ $assetsSection
       'One asset is bundled with variant, scanning directory',
       () async {
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'test_package': 'p/p/'},
+        );
 
         final List<String> assetsOnDisk = <String>['a/foo', 'a/2x/foo'];
         final List<String> assetOnManifest = <String>['a/'];
@@ -698,7 +751,11 @@ $assetsSection
       'No asset is bundled with variant, no assets or directories are listed',
       () async {
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'test_package': 'p/p/'},
+        );
 
         final List<String> assetsOnDisk = <String>['a/foo', 'a/2x/foo'];
         final List<String> assetOnManifest = <String>[];
@@ -722,7 +779,11 @@ $assetsSection
       'Expect error generating manifest, wrong non-existing directory is listed',
       () async {
         writePubspecFile('pubspec.yaml', 'test');
-        writePackageConfigFile(<String, String>{'test_package': 'p/p/'});
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'test_package': 'p/p/'},
+        );
 
         final List<String> assetOnManifest = <String>['c/'];
 
diff --git a/packages/flutter_tools/test/general.shard/asset_bundle_test.dart b/packages/flutter_tools/test/general.shard/asset_bundle_test.dart
index c1d3fb4c0e..5fc804431c 100644
--- a/packages/flutter_tools/test/general.shard/asset_bundle_test.dart
+++ b/packages/flutter_tools/test/general.shard/asset_bundle_test.dart
@@ -23,34 +23,11 @@ import 'package:standard_message_codec/standard_message_codec.dart';
 
 import '../src/common.dart';
 import '../src/context.dart';
+import '../src/package_config.dart';
 
 void main() {
   const String shaderLibDir = '/./shader_lib';
 
-  File createPackageConfig(
-    FileSystem fileSystem, {
-    Map<String, String> packages = const <String, String>{},
-  }) {
-    final File file = fileSystem.directory('.dart_tool').childFile('package_config.json');
-    file.createSync(recursive: true);
-    file.writeAsStringSync(
-      json.encode(<String, dynamic>{
-        'packages': <dynamic>[
-          ...packages.entries.map((MapEntry<String, String> entry) {
-            return <String, dynamic>{
-              'name': entry.key,
-              'rootUri': '../${entry.value}',
-              'packageUri': 'lib/',
-              'languageVersion': '3.2',
-            };
-          }),
-        ],
-        'configVersion': 2,
-      }),
-    );
-    return file;
-  }
-
   group('AssetBundle.build (using context)', () {
     late FileSystem testFileSystem;
     late Platform platform;
@@ -115,9 +92,9 @@ void main() {
     testUsingContext(
       'wildcard directories do not include subdirectories',
       () async {
-        createPackageConfig(globals.fs);
+        writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'my_app');
         globals.fs.file('pubspec.yaml').writeAsStringSync('''
-name: test
+name: my_app
 dependencies:
   flutter:
     sdk: flutter
@@ -164,14 +141,18 @@ flutter:
     testUsingContext(
       'wildcard directories are updated when filesystem changes',
       () async {
-        final File packageFile = createPackageConfig(globals.fs);
+        final File packageFile = writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+        );
+
         globals.fs
             .file(globals.fs.path.join('assets', 'foo', 'bar.txt'))
             .createSync(recursive: true);
         globals.fs.file('pubspec.yaml')
           ..createSync()
           ..writeAsStringSync(r'''
-name: example
+name: my_app
 flutter:
   assets:
     - assets/foo/
@@ -224,12 +205,15 @@ flutter:
             globals.fs.file('pubspec.yaml')
               ..createSync()
               ..writeAsStringSync(r'''
-name: example
+name: my_app
 flutter:
   assets:
     - assets/foo/
 ''');
-        final File packageConfig = createPackageConfig(globals.fs);
+        final File packageConfig = writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+        );
         final AssetBundle bundle = AssetBundleFactory.instance.createBundle();
         await bundle.build(packageConfigPath: '.dart_tool/package_config.json');
         expect(
@@ -250,7 +234,7 @@ flutter:
         globals.fs.file('pubspec.yaml')
           ..createSync()
           ..writeAsStringSync(r'''
-name: example''')
+name: my_app''')
           ..setLastModifiedSync(modifiedTime);
 
         // touch the package config to make sure its change time is after pubspec.yaml's
@@ -292,12 +276,12 @@ name: example''')
         globals.fs.file('pubspec.yaml')
           ..createSync()
           ..writeAsStringSync(r'''
-name: example
+name: my_app
 flutter:
   assets:
     - assets/foo/
 ''');
-        createPackageConfig(globals.fs);
+        writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'my_app');
         final AssetBundle bundle = AssetBundleFactory.instance.createBundle();
         await bundle.build(packageConfigPath: '.dart_tool/package_config.json');
         expect(
@@ -322,7 +306,7 @@ flutter:
     testUsingContext(
       'deferred assets are parsed',
       () async {
-        createPackageConfig(globals.fs);
+        writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'my_app');
         globals.fs
             .file(globals.fs.path.join('assets', 'foo', 'bar.txt'))
             .createSync(recursive: true);
@@ -335,7 +319,7 @@ flutter:
         globals.fs.file('pubspec.yaml')
           ..createSync()
           ..writeAsStringSync(r'''
-name: example
+name: my_app
 flutter:
   assets:
     - assets/foo/
@@ -380,7 +364,7 @@ flutter:
     testUsingContext(
       'deferred assets are parsed regularly when splitDeferredAssets Disabled',
       () async {
-        createPackageConfig(globals.fs);
+        writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'my_app');
         globals.fs
             .file(globals.fs.path.join('assets', 'foo', 'bar.txt'))
             .createSync(recursive: true);
@@ -393,7 +377,7 @@ flutter:
         globals.fs.file('pubspec.yaml')
           ..createSync()
           ..writeAsStringSync(r'''
-name: example
+name: my_app
 flutter:
   assets:
     - assets/foo/
@@ -430,7 +414,10 @@ flutter:
     testUsingContext(
       'deferred assets wildcard parsed',
       () async {
-        final File packageFile = createPackageConfig(globals.fs);
+        final File packageFile = writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+        );
         globals.fs
             .file(globals.fs.path.join('assets', 'foo', 'bar.txt'))
             .createSync(recursive: true);
@@ -443,7 +430,7 @@ flutter:
         globals.fs.file('pubspec.yaml')
           ..createSync()
           ..writeAsStringSync(r'''
-name: example
+name: my_app
 flutter:
   assets:
     - assets/foo/
@@ -523,11 +510,11 @@ flutter:
           userMessages: UserMessages(),
         );
 
-        createPackageConfig(fileSystem);
+        writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
         fileSystem.file('pubspec.yaml')
           ..createSync()
           ..writeAsStringSync(r'''
-name: example
+name: my_app
 flutter:
   assets:
     - https://mywebsite.com/images/
@@ -577,7 +564,7 @@ flutter:
           fileSystem: fileSystem,
           userMessages: UserMessages(),
         );
-        createPackageConfig(fileSystem);
+        writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
         fileSystem.file('pubspec.yaml')
           ..createSync()
           ..writeAsStringSync(r'''
@@ -612,11 +599,11 @@ flutter:
 
         final BufferLogger logger = BufferLogger.test();
         final FakePlatform platform = FakePlatform();
-        createPackageConfig(fileSystem);
+        writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
         fileSystem.file('pubspec.yaml')
           ..createSync()
           ..writeAsStringSync(r'''
-name: example
+name: my_app
 flutter:
   assets:
     - path: my-asset.txt
@@ -649,7 +636,7 @@ flutter:
         expect(bundle.entries['my-asset.txt']!.content.isModified, isFalse);
 
         fileSystem.file('pubspec.yaml').writeAsStringSync(r'''
-name: example
+name: my_app
 flutter:
   assets:
     - path: my-asset.txt
@@ -717,9 +704,9 @@ flutter:
     testUsingContext(
       'pubspec contains an asset',
       () async {
-        createPackageConfig(globals.fs);
+        writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'my_app');
         globals.fs.file('pubspec.yaml').writeAsStringSync(r'''
-name: test
+name: my_app
 dependencies:
   flutter:
     sdk: flutter
@@ -809,12 +796,12 @@ flutter:
   testUsingContext(
     'does not unnecessarily recreate asset manifest, font manifest, license',
     () async {
-      createPackageConfig(globals.fs);
+      writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'my_app');
       globals.fs.file(globals.fs.path.join('assets', 'foo', 'bar.txt')).createSync(recursive: true);
       globals.fs.file('pubspec.yaml')
         ..createSync()
         ..writeAsStringSync(r'''
-name: example
+name: my_app
 flutter:
 assets:
   - assets/foo/bar.txt
@@ -843,12 +830,12 @@ assets:
     'inserts dummy file into additionalDependencies when '
     'wildcards are used',
     () async {
-      createPackageConfig(globals.fs);
+      writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'my_app');
       globals.fs.file(globals.fs.path.join('assets', 'bar.txt')).createSync(recursive: true);
       globals.fs.file('pubspec.yaml')
         ..createSync()
         ..writeAsStringSync(r'''
-name: example
+name: my_app
 flutter:
   assets:
     - assets/
@@ -872,12 +859,12 @@ flutter:
     'Does not insert dummy file into additionalDependencies '
     'when wildcards are not used',
     () async {
-      createPackageConfig(globals.fs);
+      writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'my_app');
       globals.fs.file(globals.fs.path.join('assets', 'bar.txt')).createSync(recursive: true);
       globals.fs.file('pubspec.yaml')
         ..createSync()
         ..writeAsStringSync(r'''
-name: example
+name: my_app
 flutter:
   assets:
     - assets/bar.txt
@@ -920,11 +907,11 @@ flutter:
     testUsingContext(
       'Including a shader triggers the shader compiler',
       () async {
-        createPackageConfig(fileSystem);
+        writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'my_app');
         fileSystem.file('pubspec.yaml')
           ..createSync()
           ..writeAsStringSync(r'''
-  name: example
+  name: my_app
   flutter:
     shaders:
       - assets/shader.frag
@@ -978,11 +965,11 @@ flutter:
     testUsingContext(
       'Included shaders are compiled for the web',
       () async {
-        createPackageConfig(fileSystem);
+        writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'my_app');
         fileSystem.file('pubspec.yaml')
           ..createSync()
           ..writeAsStringSync(r'''
-  name: example
+  name: my_app
   flutter:
     shaders:
       - assets/shader.frag
@@ -1040,7 +1027,7 @@ flutter:
     testUsingContext(
       'Material shaders are compiled for the web',
       () async {
-        createPackageConfig(fileSystem);
+        writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'my_app');
 
         final String materialIconsPath = fileSystem.path.join(
           getFlutterRoot(),
@@ -1090,7 +1077,7 @@ flutter:
         fileSystem.file('pubspec.yaml')
           ..createSync()
           ..writeAsStringSync(r'''
-  name: example
+  name: my_app
   flutter:
     uses-material-design: true
   ''');
@@ -1130,12 +1117,16 @@ flutter:
     'Does not insert dummy file into additionalDependencies '
     'when wildcards are used by dependencies',
     () async {
-      createPackageConfig(globals.fs, packages: <String, String>{'example': '', 'foo': 'foo'});
+      writePackageConfigFile(
+        directory: globals.fs.currentDirectory,
+        mainLibName: 'my_app',
+        packages: <String, String>{'foo': 'foo'},
+      );
       globals.fs.file(globals.fs.path.join('assets', 'foo', 'bar.txt')).createSync(recursive: true);
       globals.fs.file('pubspec.yaml')
         ..createSync()
         ..writeAsStringSync(r'''
-name: example
+name: my_app
 dependencies:
   foo: any
 ''');
@@ -1164,12 +1155,16 @@ flutter:
   testUsingContext(
     'does not track wildcard directories from dependencies',
     () async {
-      createPackageConfig(globals.fs, packages: <String, String>{'example': '', 'foo': 'foo'});
+      writePackageConfigFile(
+        directory: globals.fs.currentDirectory,
+        mainLibName: 'my_app',
+        packages: <String, String>{'foo': 'foo'},
+      );
       globals.fs.file(globals.fs.path.join('assets', 'foo', 'bar.txt')).createSync(recursive: true);
       globals.fs.file('pubspec.yaml')
         ..createSync()
         ..writeAsStringSync(r'''
-name: example
+name: my_app
 dependencies:
   foo: any
 ''');
@@ -1215,12 +1210,16 @@ flutter:
     'reports package that causes asset bundle error when it is '
     'a dependency',
     () async {
-      createPackageConfig(globals.fs, packages: <String, String>{'example': '', 'foo': 'foo'});
+      writePackageConfigFile(
+        directory: globals.fs.currentDirectory,
+        mainLibName: 'my_app',
+        packages: <String, String>{'foo': 'foo'},
+      );
       globals.fs.file(globals.fs.path.join('assets', 'foo', 'bar.txt')).createSync(recursive: true);
       globals.fs.file('pubspec.yaml')
         ..createSync()
         ..writeAsStringSync(r'''
-name: example
+name: my_app
 dependencies:
   foo: any
 ''');
@@ -1249,11 +1248,15 @@ flutter:
     'does not report package that causes asset bundle error '
     'when it is from own pubspec',
     () async {
-      createPackageConfig(globals.fs, packages: <String, String>{'example': '', 'foo': 'foo'});
+      writePackageConfigFile(
+        directory: globals.fs.currentDirectory,
+        mainLibName: 'my_app',
+        packages: <String, String>{'foo': 'foo'},
+      );
       globals.fs.file('pubspec.yaml')
         ..createSync()
         ..writeAsStringSync(r'''
-name: example
+name: my_app
 flutter:
   assets:
     - bar.txt
@@ -1274,11 +1277,15 @@ flutter:
     'does not include Material Design assets if uses-material-design: true is '
     'specified only by a dependency',
     () async {
-      createPackageConfig(globals.fs, packages: <String, String>{'example': '', 'foo': 'foo'});
+      writePackageConfigFile(
+        directory: globals.fs.currentDirectory,
+        mainLibName: 'my_app',
+        packages: <String, String>{'foo': 'foo'},
+      );
       globals.fs.file('pubspec.yaml')
         ..createSync()
         ..writeAsStringSync(r'''
-name: example
+name: my_app
 dependencies:
   foo: any
 
@@ -1310,11 +1317,11 @@ flutter:
   testUsingContext(
     'does not include assets in project directories as asset variants',
     () async {
-      createPackageConfig(globals.fs, packages: <String, String>{'example': ''});
+      writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'my_app');
       globals.fs.file('pubspec.yaml')
         ..createSync()
         ..writeAsStringSync(r'''
-name: example
+name: my_app
 
 flutter:
   assets:
@@ -1354,11 +1361,11 @@ flutter:
   testUsingContext(
     'deferred and regular assets are included in manifest alphabetically',
     () async {
-      createPackageConfig(globals.fs, packages: <String, String>{'example': ''});
+      writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'my_app');
       globals.fs.file('pubspec.yaml')
         ..createSync()
         ..writeAsStringSync(r'''
-name: example
+name: my_app
 
 flutter:
   assets:
diff --git a/packages/flutter_tools/test/general.shard/asset_bundle_variant_test.dart b/packages/flutter_tools/test/general.shard/asset_bundle_variant_test.dart
index e1abe7b136..b9133404ca 100644
--- a/packages/flutter_tools/test/general.shard/asset_bundle_variant_test.dart
+++ b/packages/flutter_tools/test/general.shard/asset_bundle_variant_test.dart
@@ -19,6 +19,7 @@ import 'package:flutter_tools/src/project.dart';
 import 'package:standard_message_codec/standard_message_codec.dart';
 
 import '../src/common.dart';
+import '../src/package_config.dart';
 
 void main() {
   Future<Map<String, List<String>>> extractAssetManifestJsonFromBundle(
@@ -58,14 +59,7 @@ void main() {
         fileSystem: fs,
         userMessages: UserMessages(),
       );
-      fs.directory('.dart_tool').childFile('package_config.json')
-        ..createSync(recursive: true)
-        ..writeAsStringSync('''
-{
-  "configVersion": 2,
-  "packages": []
-}
-''');
+      writePackageConfigFile(directory: fs.currentDirectory, mainLibName: 'test');
     });
 
     void createPubspec({required List<String> assets}) {
@@ -292,14 +286,7 @@ ${assets.map((String entry) => '    - $entry').join('\n')}
         userMessages: UserMessages(),
       );
 
-      fs.directory('.dart_tool').childFile('package_config.json')
-        ..createSync(recursive: true)
-        ..writeAsStringSync('''
-{
-  "configVersion": 2,
-  "packages": []
-}
-''');
+      writePackageConfigFile(directory: fs.currentDirectory, mainLibName: 'test');
 
       fs.file('pubspec.yaml').writeAsStringSync('''
 name: test
diff --git a/packages/flutter_tools/test/general.shard/build_system/targets/android_test.dart b/packages/flutter_tools/test/general.shard/build_system/targets/android_test.dart
index 1eca6d2a53..f07f0670e5 100644
--- a/packages/flutter_tools/test/general.shard/build_system/targets/android_test.dart
+++ b/packages/flutter_tools/test/general.shard/build_system/targets/android_test.dart
@@ -16,6 +16,7 @@ import 'package:flutter_tools/src/build_system/targets/android.dart';
 import '../../../src/common.dart';
 import '../../../src/context.dart';
 import '../../../src/fake_process_manager.dart';
+import '../../../src/package_config.dart';
 
 void main() {
   late FakeProcessManager processManager;
@@ -552,10 +553,7 @@ void main() {
       fileSystem
           .file('pubspec.yaml')
           .writeAsStringSync('name: hello\nflutter:\n  shaders:\n    - shader.glsl');
-      fileSystem
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
+      writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'hello');
       fileSystem.file('shader.glsl').writeAsStringSync('test');
 
       processManager.addCommands(<FakeCommand>[
diff --git a/packages/flutter_tools/test/general.shard/build_system/targets/assets_test.dart b/packages/flutter_tools/test/general.shard/build_system/targets/assets_test.dart
index 968cd883f1..f8760cf1a3 100644
--- a/packages/flutter_tools/test/general.shard/build_system/targets/assets_test.dart
+++ b/packages/flutter_tools/test/general.shard/build_system/targets/assets_test.dart
@@ -21,6 +21,7 @@ import 'package:flutter_tools/src/globals.dart' as globals;
 import '../../../src/common.dart';
 import '../../../src/context.dart';
 import '../../../src/fake_process_manager.dart';
+import '../../../src/package_config.dart';
 
 void main() {
   late Environment environment;
@@ -47,7 +48,6 @@ void main() {
         .createSync(recursive: true);
     fileSystem.file('assets/foo/bar.png').createSync(recursive: true);
     fileSystem.file('assets/wildcard/#bar.png').createSync(recursive: true);
-    fileSystem.directory('.dart_tool').childFile('package_config.json').createSync(recursive: true);
     fileSystem.file('pubspec.yaml')
       ..createSync()
       ..writeAsStringSync('''
@@ -64,20 +64,11 @@ flutter:
   testUsingContext(
     'includes LICENSE file inputs in dependencies',
     () async {
-      fileSystem.directory('.dart_tool').childFile('package_config.json')
-        ..createSync(recursive: true)
-        ..writeAsStringSync('''
-{
-  "configVersion": 2,
-  "packages": [
-    {
-      "name": "foo",
-      "rootUri": "file:///bar",
-      "packageUri": "lib/"
-    }
-  ]
-}
-''');
+      writePackageConfigFile(
+        directory: globals.fs.currentDirectory,
+        mainLibName: 'example',
+        packages: <String, String>{'foo': 'bar'},
+      );
       fileSystem.file('bar/LICENSE')
         ..createSync(recursive: true)
         ..writeAsStringSync('THIS IS A LICENSE');
@@ -104,6 +95,7 @@ flutter:
   testUsingContext(
     'Copies files to correct asset directory',
     () async {
+      writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'example');
       await const CopyAssets().build(environment);
 
       expect(
@@ -152,6 +144,7 @@ flutter:
         flavors:
           - strawberry
   ''');
+          writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'example');
 
           fileSystem.file('assets/common/image.png').createSync(recursive: true);
           fileSystem.file('assets/vanilla/ice-cream.png').createSync(recursive: true);
@@ -200,6 +193,7 @@ flutter:
         flavors:
           - strawberry
   ''');
+          writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'example');
 
           fileSystem.file('assets/common/image.png').createSync(recursive: true);
           fileSystem.file('assets/vanilla/ice-cream.png').createSync(recursive: true);
@@ -251,11 +245,6 @@ flutter:
         defines: <String, String>{kBuildMode: BuildMode.debug.cliName},
       );
 
-      fileSystem
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
-
       fileSystem.file('pubspec.yaml')
         ..createSync()
         ..writeAsStringSync('''
@@ -268,6 +257,8 @@ flutter:
           args: ["-a", "-b", "--color", "green"]
 ''');
 
+      writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'example');
+
       fileSystem.file('input.txt')
         ..createSync(recursive: true)
         ..writeAsStringSync('abc');
@@ -341,11 +332,6 @@ flutter:
         defines: <String, String>{kBuildMode: BuildMode.debug.cliName},
       );
 
-      fileSystem
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
-
       fileSystem.file('pubspec.yaml')
         ..createSync()
         ..writeAsStringSync('''
@@ -358,6 +344,8 @@ flutter:
           args: ["-a", "-b", "--color", "green"]
 ''');
 
+      writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'example');
+
       await fileSystem.file('input.txt').create(recursive: true);
 
       await expectToolExitLater(
@@ -441,11 +429,6 @@ flutter:
         defines: <String, String>{kBuildMode: BuildMode.debug.cliName},
       );
 
-      fileSystem
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
-
       fileSystem.file('pubspec.yaml')
         ..createSync()
         ..writeAsStringSync('''
@@ -457,6 +440,8 @@ flutter:
           - package: my_capitalizer_transformer
   ''');
 
+      writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'example');
+
       fileSystem.file('input.txt')
         ..createSync(recursive: true)
         ..writeAsStringSync('abc');
diff --git a/packages/flutter_tools/test/general.shard/build_system/targets/dart_plugin_registrant_test.dart b/packages/flutter_tools/test/general.shard/build_system/targets/dart_plugin_registrant_test.dart
index 6e5cf102f6..0ef4a44a26 100644
--- a/packages/flutter_tools/test/general.shard/build_system/targets/dart_plugin_registrant_test.dart
+++ b/packages/flutter_tools/test/general.shard/build_system/targets/dart_plugin_registrant_test.dart
@@ -17,6 +17,7 @@ import '../../../src/common.dart';
 import '../../../src/context.dart';
 import '../../../src/fake_pub_deps.dart';
 import '../../../src/fakes.dart';
+import '../../../src/package_config.dart';
 
 const String _kEmptyPubspecFile = '''
 name: path_provider_example
@@ -26,40 +27,6 @@ dependencies:
     sdk: flutter
 ''';
 
-const String _kEmptyPackageJson = '''
-{
-  "configVersion": 2,
-  "packages": [
-     {
-      "name": "path_provider_example",
-      "rootUri": "../",
-      "packageUri": "lib/",
-      "languageVersion": "2.12"
-    }
-  ]
-}
-''';
-
-const String _kSamplePackageJson = '''
-{
-  "configVersion": 2,
-  "packages": [
-    {
-      "name": "path_provider_linux",
-      "rootUri": "/path_provider_linux",
-      "packageUri": "lib/",
-      "languageVersion": "2.12"
-    },
-    {
-      "name": "path_provider_example",
-      "rootUri": "../",
-      "packageUri": "lib/",
-      "languageVersion": "2.12"
-    }
-  ]
-}
-''';
-
 const String _kSamplePubspecFile = '''
 name: path_provider_example
 description: Demonstrates how to use the path_provider plugin.
@@ -174,11 +141,15 @@ void main() {
           generateDartPluginRegistry: true,
         );
 
-        projectDir.childDirectory('.dart_tool').childFile('package_config.json')
-          ..createSync(recursive: true)
-          ..writeAsStringSync(_kSamplePackageJson);
+        writePackageConfigFile(
+          directory: projectDir,
+          mainLibName: 'path_provider_example',
+          packages: <String, String>{'path_provider_linux': '/path_provider_linux'},
+        );
 
-        projectDir.childFile('pubspec.yaml').createSync();
+        projectDir.childFile('pubspec.yaml').writeAsStringSync('''
+name: path_provider_example
+''');
 
         final FlutterProject testProject = FlutterProject.fromDirectoryTest(projectDir);
         await DartPluginRegistrantTarget.test(testProject).build(environment);
@@ -213,9 +184,12 @@ void main() {
           generateDartPluginRegistry: true,
         );
 
-        projectDir.childDirectory('.dart_tool').childFile('package_config.json')
-          ..createSync(recursive: true)
-          ..writeAsStringSync(_kSamplePackageJson);
+        writePackageConfigFile(
+          directory: projectDir,
+          mainLibName: 'path_provider_example',
+          packages: <String, String>{'path_provider_linux': '/path_provider_linux'},
+          languageVersions: <String, String>{'path_provider_example': '2.12'},
+        );
 
         projectDir.childFile('pubspec.yaml').writeAsStringSync(_kSamplePubspecFile);
 
@@ -296,10 +270,11 @@ void main() {
           },
           generateDartPluginRegistry: true,
         );
-        final File config =
-            projectDir.childDirectory('.dart_tool').childFile('package_config.json')
-              ..createSync(recursive: true)
-              ..writeAsStringSync(_kSamplePackageJson);
+        writePackageConfigFile(
+          directory: projectDir,
+          mainLibName: 'path_provider_example',
+          packages: <String, String>{'path_provider_linux': '/path_provider_linux'},
+        );
 
         final File pubspec = projectDir.childFile('pubspec.yaml')
           ..writeAsStringSync(_kSamplePubspecFile);
@@ -321,7 +296,7 @@ void main() {
 
         // Simulate a user removing everything from pubspec.yaml.
         pubspec.writeAsStringSync(_kEmptyPubspecFile);
-        config.writeAsStringSync(_kEmptyPackageJson);
+        writePackageConfigFile(directory: projectDir, mainLibName: 'path_provider_example');
 
         await DartPluginRegistrantTarget.test(testProject).build(environment);
         expect(generatedMain.existsSync(), isFalse);
@@ -350,9 +325,11 @@ void main() {
           generateDartPluginRegistry: true,
         );
 
-        projectDir.childDirectory('.dart_tool').childFile('package_config.json')
-          ..createSync(recursive: true)
-          ..writeAsStringSync(_kSamplePackageJson);
+        writePackageConfigFile(
+          directory: projectDir,
+          mainLibName: 'path_provider_example',
+          packages: <String, String>{'path_provider_linux': '/path_provider_linux'},
+        );
 
         projectDir.childFile('pubspec.yaml').writeAsStringSync(_kSamplePubspecFile);
 
diff --git a/packages/flutter_tools/test/general.shard/build_system/targets/ios_test.dart b/packages/flutter_tools/test/general.shard/build_system/targets/ios_test.dart
index eae22b993d..f1a1615fe1 100644
--- a/packages/flutter_tools/test/general.shard/build_system/targets/ios_test.dart
+++ b/packages/flutter_tools/test/general.shard/build_system/targets/ios_test.dart
@@ -20,6 +20,7 @@ import '../../../src/common.dart';
 import '../../../src/context.dart';
 import '../../../src/fake_process_manager.dart';
 import '../../../src/fakes.dart';
+import '../../../src/package_config.dart';
 
 final Platform macPlatform = FakePlatform(
   operatingSystem: 'macos',
@@ -208,11 +209,8 @@ void main() {
           .file(artifacts.getArtifactPath(Artifact.isolateSnapshotData, mode: BuildMode.debug))
           .createSync();
       // Project info
-      fileSystem.file('pubspec.yaml').writeAsStringSync('name: hello');
-      fileSystem
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
+      fileSystem.file('pubspec.yaml').writeAsStringSync('name: my_app');
+      writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
       // Plist file
       fileSystem
           .file(fileSystem.path.join('ios', 'Flutter', 'AppFrameworkInfo.plist'))
@@ -390,11 +388,8 @@ void main() {
       // Project info
       fileSystem
           .file('pubspec.yaml')
-          .writeAsStringSync('name: hello\nflutter:\n  shaders:\n    - shader.glsl');
-      fileSystem
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
+          .writeAsStringSync('name: my_app\nflutter:\n  shaders:\n    - shader.glsl');
+      writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
       // Plist file
       fileSystem
           .file(fileSystem.path.join('ios', 'Flutter', 'AppFrameworkInfo.plist'))
@@ -474,11 +469,9 @@ void main() {
       environment.defines[kXcodeAction] = 'build';
 
       // Project info
-      fileSystem.file('pubspec.yaml').writeAsStringSync('name: hello');
-      fileSystem
-          .directory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
+      fileSystem.file('pubspec.yaml').writeAsStringSync('name: my_app');
+      writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
+
       // Plist file
       fileSystem
           .file(fileSystem.path.join('ios', 'Flutter', 'AppFrameworkInfo.plist'))
diff --git a/packages/flutter_tools/test/general.shard/build_system/targets/web_test.dart b/packages/flutter_tools/test/general.shard/build_system/targets/web_test.dart
index be14a814e5..a8347982b4 100644
--- a/packages/flutter_tools/test/general.shard/build_system/targets/web_test.dart
+++ b/packages/flutter_tools/test/general.shard/build_system/targets/web_test.dart
@@ -23,6 +23,7 @@ import '../../../src/common.dart';
 import '../../../src/fake_process_manager.dart';
 import '../../../src/fake_pub_deps.dart';
 import '../../../src/fakes.dart';
+import '../../../src/package_config.dart';
 import '../../../src/testbed.dart';
 
 const List<String> _kDart2jsLinuxArgs = <String>[
@@ -61,21 +62,16 @@ void main() {
   setUp(() {
     testbed = Testbed(
       setup: () {
-        globals.fs.directory('.dart_tool').childFile('package_config.json')
-          ..createSync(recursive: true)
-          ..writeAsStringSync('''
-{
-  "configVersion": 2,
-  "packages": [
-    {
-      "name": "foo",
-      "rootUri": "../foo/",
-      "packageUri": "lib/",
-      "languageVersion": "2.7"
-    }
-  ]
-}
+        globals.fs.currentDirectory.childFile('pubspec.yaml').writeAsStringSync('''
+name: foo
 ''');
+
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'foo': 'foo/'},
+          languageVersions: <String, String>{'foo': '2.7'},
+        );
         globals.fs.currentDirectory.childDirectory('bar').createSync();
         processManager = FakeProcessManager.empty();
         globals.fs
diff --git a/packages/flutter_tools/test/general.shard/custom_devices/custom_device_test.dart b/packages/flutter_tools/test/general.shard/custom_devices/custom_device_test.dart
index 0dce3098e4..bf0f9f2dda 100644
--- a/packages/flutter_tools/test/general.shard/custom_devices/custom_device_test.dart
+++ b/packages/flutter_tools/test/general.shard/custom_devices/custom_device_test.dart
@@ -26,6 +26,7 @@ import 'package:test/fake.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fakes.dart';
+import '../../src/package_config.dart';
 
 void _writeCustomDevicesConfigFile(Directory dir, List<CustomDeviceConfig> configs) {
   dir.createSync();
@@ -298,7 +299,7 @@ void main() {
   testWithoutContext('CustomDevice.isSupportedForProject is true with editable host app', () async {
     final MemoryFileSystem fileSystem = MemoryFileSystem.test();
     fileSystem.file('pubspec.yaml').createSync();
-    fileSystem.directory('.dart_tool').childFile('package_config.json').createSync(recursive: true);
+    writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
 
     final FlutterProject flutterProject = _setUpFlutterProject(fileSystem.currentDirectory);
 
diff --git a/packages/flutter_tools/test/general.shard/dart/pub_get_test.dart b/packages/flutter_tools/test/general.shard/dart/pub_get_test.dart
index 2010cd7f54..365102fb21 100644
--- a/packages/flutter_tools/test/general.shard/dart/pub_get_test.dart
+++ b/packages/flutter_tools/test/general.shard/dart/pub_get_test.dart
@@ -17,6 +17,7 @@ import 'package:flutter_tools/src/project.dart';
 import '../../src/common.dart';
 import '../../src/fake_process_manager.dart';
 import '../../src/fakes.dart';
+import '../../src/package_config.dart';
 
 void main() {
   setUpAll(() {
@@ -750,12 +751,11 @@ exit code: 66
           'get',
           '--example',
         ],
-        onRun: (_) {
-          fileSystem.currentDirectory
-              .childDirectory('.dart_tool')
-              .childFile('package_config.json')
-              .createSync(recursive: true);
-        },
+        onRun:
+            (_) => writePackageConfigFile(
+              directory: fileSystem.currentDirectory,
+              mainLibName: 'my_app',
+            ),
       ),
     ]);
 
@@ -907,12 +907,11 @@ exit code: 66
           'FLUTTER_ROOT': '',
           'PUB_ENVIRONMENT': 'flutter_cli:flutter_tests',
         },
-        onRun: (_) {
-          fileSystem.currentDirectory
-              .childDirectory('.dart_tool')
-              .childFile('package_config.json')
-              .createSync(recursive: true);
-        },
+        onRun:
+            (_) => writePackageConfigFile(
+              directory: fileSystem.currentDirectory,
+              mainLibName: 'my_app',
+            ),
       ),
     ]);
 
diff --git a/packages/flutter_tools/test/general.shard/dart_plugin_test.dart b/packages/flutter_tools/test/general.shard/dart_plugin_test.dart
index f445859218..b228a59800 100644
--- a/packages/flutter_tools/test/general.shard/dart_plugin_test.dart
+++ b/packages/flutter_tools/test/general.shard/dart_plugin_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.
 
-import 'dart:convert';
-
 import 'package:file/file.dart';
 import 'package:file/memory.dart';
 import 'package:flutter_tools/src/dart/package_map.dart';
@@ -23,6 +21,7 @@ import '../src/common.dart';
 import '../src/context.dart';
 import '../src/fake_pub_deps.dart';
 import '../src/fakes.dart';
+import '../src/package_config.dart';
 
 void main() {
   // TODO(matanlurey): Remove after `explicit-package-dependencies` is enabled by default.
@@ -47,10 +46,7 @@ void main() {
             ..flutterPluginsFile = directory.childFile('.flutter-plugins')
             ..flutterPluginsDependenciesFile = directory.childFile('.flutter-plugins-dependencies')
             ..dartPluginRegistrant = directory.childFile('dart_plugin_registrant.dart');
-      flutterProject.directory
-          .childDirectory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
+      writePackageConfigFile(directory: flutterProject.directory, mainLibName: 'my_app');
     });
 
     group('resolvePlatformImplementation', () {
@@ -1282,7 +1278,7 @@ void main() {
         'Plugin without platform support throws tool exit',
         () async {
           flutterProject.isModule = false;
-
+          flutterManifest.dependencies.add('url_launcher_macos');
           createFakeDartPlugins(flutterProject, flutterManifest, fs, <String, String>{
             'url_launcher_macos': '''
   flutter:
@@ -1375,6 +1371,7 @@ void main() {
         'Does not create new entrypoint if there are no platform resolutions',
         () async {
           flutterProject.isModule = false;
+          createFakeDartPlugins(flutterProject, flutterManifest, fs, <String, String>{});
 
           final Directory libDir = flutterProject.directory.childDirectory('lib');
           libDir.createSync(recursive: true);
@@ -1456,23 +1453,6 @@ void main() {
   });
 }
 
-void addToPackageConfig(FlutterProject project, String name, Directory packageDir) {
-  final File packageConfigFile = project.directory
-      .childDirectory('.dart_tool')
-      .childFile('package_config.json');
-
-  final Map<String, Object?> packageConfig =
-      jsonDecode(packageConfigFile.readAsStringSync()) as Map<String, Object?>;
-
-  (packageConfig['packages']! as List<Object?>).add(<String, Object?>{
-    'name': name,
-    'rootUri': packageDir.uri.toString(),
-    'packageUri': 'lib/',
-  });
-
-  packageConfigFile.writeAsStringSync(jsonEncode(packageConfig));
-}
-
 void createFakeDartPlugins(
   FakeFlutterProject flutterProject,
   FakeFlutterManifest flutterManifest,
@@ -1480,21 +1460,18 @@ void createFakeDartPlugins(
   Map<String, String> plugins,
 ) {
   final Directory fakePubCache = fs.systemTempDirectory.childDirectory('cache');
-
-  flutterProject.directory.childDirectory('.dart_tool').childFile('package_config.json')
-    ..deleteSync(recursive: true)
-    ..createSync(recursive: true)
-    ..writeAsStringSync('''
-{
-  "packages": [],
-  "configVersion": 2
-}
-''');
+  writePackageConfigFile(
+    directory: flutterProject.directory,
+    mainLibName: flutterProject.manifest.appName,
+    packages: <String, String>{
+      for (final String name in plugins.keys)
+        name: fakePubCache.childDirectory(name).uri.toString(),
+    },
+  );
 
   for (final MapEntry<String, String> entry in plugins.entries) {
     final String name = fs.path.basename(entry.key);
     final Directory pluginDirectory = fakePubCache.childDirectory(name);
-    addToPackageConfig(flutterProject, name, pluginDirectory);
     pluginDirectory.childFile('pubspec.yaml')
       ..createSync(recursive: true)
       ..writeAsStringSync(entry.value);
@@ -1505,6 +1482,9 @@ void createFakeDartPlugins(
 class FakeFlutterManifest extends Fake implements FlutterManifest {
   @override
   Set<String> dependencies = <String>{};
+
+  @override
+  String get appName => 'myapp';
 }
 
 class FakeFlutterProject extends Fake implements FlutterProject {
diff --git a/packages/flutter_tools/test/general.shard/hot_test.dart b/packages/flutter_tools/test/general.shard/hot_test.dart
index ccfa169dbf..f32bf32f78 100644
--- a/packages/flutter_tools/test/general.shard/hot_test.dart
+++ b/packages/flutter_tools/test/general.shard/hot_test.dart
@@ -24,6 +24,7 @@ import '../src/common.dart';
 import '../src/context.dart';
 import '../src/fake_pub_deps.dart';
 import '../src/fakes.dart';
+import '../src/package_config.dart';
 import 'hot_shared.dart';
 
 void main() {
@@ -182,14 +183,7 @@ void main() {
       testUsingContext(
         'setupHotRestart function fails',
         () async {
-          fileSystem.directory('.dart_tool').childFile('package_config.json')
-            ..createSync(recursive: true)
-            ..writeAsStringSync('''
-{
-  "configVersion": 2,
-  "packages": []
-}
-''');
+          writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
           final FakeDevice device = FakeDevice();
           final List<FlutterDevice> devices = <FlutterDevice>[FakeFlutterDevice(device)];
           final OperationResult result = await HotRunner(
@@ -217,14 +211,7 @@ void main() {
       testUsingContext(
         'setupHotReload function fails',
         () async {
-          fileSystem.directory('.dart_tool').childFile('package_config.json')
-            ..createSync(recursive: true)
-            ..writeAsStringSync('''
-{
-  "configVersion": 2,
-  "packages": []
-}
-''');
+          writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
           final FakeDevice device = FakeDevice();
           final FakeFlutterDevice fakeFlutterDevice = FakeFlutterDevice(device);
           final List<FlutterDevice> devices = <FlutterDevice>[fakeFlutterDevice];
@@ -273,14 +260,7 @@ void main() {
       testUsingContext(
         'shutdown hook called after signal',
         () async {
-          fileSystem.directory('.dart_tool').childFile('package_config.json')
-            ..createSync(recursive: true)
-            ..writeAsStringSync('''
-{
-  "configVersion": 2,
-  "packages": []
-}
-''');
+          writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
           final FakeDevice device = FakeDevice();
           final List<FlutterDevice> devices = <FlutterDevice>[
             FlutterDevice(
@@ -310,14 +290,7 @@ void main() {
       testUsingContext(
         'shutdown hook called after app stop',
         () async {
-          fileSystem.directory('.dart_tool').childFile('package_config.json')
-            ..createSync(recursive: true)
-            ..writeAsStringSync('''
-{
-  "configVersion": 2,
-  "packages": []
-}
-''');
+          writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
           final FakeDevice device = FakeDevice();
           final List<FlutterDevice> devices = <FlutterDevice>[
             FlutterDevice(
@@ -680,14 +653,7 @@ void main() {
       'Exits with code 2 when HttpException is thrown '
       'during VM service connection',
       () async {
-        fileSystem.directory('.dart_tool').childFile('package_config.json')
-          ..createSync(recursive: true)
-          ..writeAsStringSync('''
-{
-  "configVersion": 2,
-  "packages": []
-}
-''');
+        writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
 
         final FakeResidentCompiler residentCompiler = FakeResidentCompiler();
         final FakeDevice device = FakeDevice();
diff --git a/packages/flutter_tools/test/general.shard/ios/ios_device_start_nonprebuilt_test.dart b/packages/flutter_tools/test/general.shard/ios/ios_device_start_nonprebuilt_test.dart
index f707fbe6d2..1840317fc3 100644
--- a/packages/flutter_tools/test/general.shard/ios/ios_device_start_nonprebuilt_test.dart
+++ b/packages/flutter_tools/test/general.shard/ios/ios_device_start_nonprebuilt_test.dart
@@ -37,6 +37,7 @@ import '../../src/fake_devices.dart';
 import '../../src/fake_process_manager.dart';
 import '../../src/fake_pub_deps.dart';
 import '../../src/fakes.dart';
+import '../../src/package_config.dart';
 
 List<String> _xattrArgs(FlutterProject flutterProject) {
   return <String>['xattr', '-r', '-d', 'com.apple.FinderInfo', flutterProject.directory.path];
@@ -1156,8 +1157,10 @@ void main() {
 }
 
 void setUpIOSProject(FileSystem fileSystem, {bool createWorkspace = true}) {
-  fileSystem.file('pubspec.yaml').createSync();
-  fileSystem.directory('.dart_tool').childFile('package_config.json').createSync(recursive: true);
+  fileSystem.file('pubspec.yaml').writeAsStringSync('''
+name: my_app
+''');
+  writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
   fileSystem.directory('ios').createSync();
   if (createWorkspace) {
     fileSystem.directory('ios/Runner.xcworkspace').createSync();
diff --git a/packages/flutter_tools/test/general.shard/ios/mac_test.dart b/packages/flutter_tools/test/general.shard/ios/mac_test.dart
index aa7e1d9d7a..3de383030c 100644
--- a/packages/flutter_tools/test/general.shard/ios/mac_test.dart
+++ b/packages/flutter_tools/test/general.shard/ios/mac_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.
 
-import 'dart:convert';
-
 import 'package:file/file.dart';
 import 'package:file/memory.dart';
 import 'package:flutter_tools/src/artifacts.dart';
@@ -28,6 +26,7 @@ import '../../src/context.dart';
 import '../../src/fake_process_manager.dart';
 import '../../src/fake_pub_deps.dart';
 import '../../src/fakes.dart';
+import '../../src/package_config.dart';
 
 void main() {
   late BufferLogger logger;
@@ -658,7 +657,9 @@ duplicate symbol '_$s29plugin_1_name23PluginNamePluginC9setDouble3key5valueySS_S
         final FakeFlutterProject project = FakeFlutterProject(fileSystem: fs);
         project.ios.podfile.createSync(recursive: true);
         project.manifest = FakeFlutterManifest();
-        createFakePlugins(project, fs, <String>['plugin_1_name', 'plugin_2_name']);
+        final List<String> pluginNames = <String>['plugin_1_name', 'plugin_2_name'];
+        project.manifest.dependencies.addAll(pluginNames);
+        createFakePlugins(project, fs, pluginNames);
         fs.systemTempDirectory
             .childFile('cache/plugin_1_name/ios/plugin_1_name/Package.swift')
             .createSync(recursive: true);
@@ -770,23 +771,6 @@ duplicate symbol '_$s29plugin_1_name23PluginNamePluginC9setDouble3key5valueySS_S
   });
 }
 
-void addToPackageConfig(FlutterProject flutterProject, String name, Directory packageDir) {
-  final File packageConfigFile = flutterProject.directory
-      .childDirectory('.dart_tool')
-      .childFile('package_config.json');
-
-  final Map<String, Object?> packageConfig =
-      jsonDecode(packageConfigFile.readAsStringSync()) as Map<String, Object?>;
-
-  (packageConfig['packages']! as List<Object?>).add(<String, Object?>{
-    'name': name,
-    'rootUri': packageDir.uri.toString(),
-    'packageUri': 'lib/',
-  });
-
-  packageConfigFile.writeAsStringSync(jsonEncode(packageConfig));
-}
-
 void createFakePlugins(
   FlutterProject flutterProject,
   FileSystem fileSystem,
@@ -803,17 +787,15 @@ void createFakePlugins(
   ''';
 
   final Directory fakePubCache = fileSystem.systemTempDirectory.childDirectory('cache');
-  flutterProject.directory.childDirectory('.dart_tool').childFile('package_config.json')
-    ..createSync(recursive: true)
-    ..writeAsStringSync('''
-{
-  "packages": [],
-  "configVersion": 2
-}
-''');
+  writePackageConfigFile(
+    directory: flutterProject.directory,
+    mainLibName: 'my_app',
+    packages: <String, String>{
+      for (final String name in pluginNames) name: fakePubCache.childDirectory(name).path,
+    },
+  );
   for (final String name in pluginNames) {
     final Directory pluginDirectory = fakePubCache.childDirectory(name);
-    addToPackageConfig(flutterProject, name, pluginDirectory);
     pluginDirectory.childFile('pubspec.yaml')
       ..createSync(recursive: true)
       ..writeAsStringSync(pluginYamlTemplate.replaceAll('PLUGIN_CLASS', name));
diff --git a/packages/flutter_tools/test/general.shard/isolated/build_system/targets/native_assets_test.dart b/packages/flutter_tools/test/general.shard/isolated/build_system/targets/native_assets_test.dart
index 9812e9b284..5c2f6b6dda 100644
--- a/packages/flutter_tools/test/general.shard/isolated/build_system/targets/native_assets_test.dart
+++ b/packages/flutter_tools/test/general.shard/isolated/build_system/targets/native_assets_test.dart
@@ -18,6 +18,7 @@ import 'package:native_assets_cli/code_assets_builder.dart';
 import '../../../../src/common.dart';
 import '../../../../src/context.dart';
 import '../../../../src/fakes.dart';
+import '../../../../src/package_config.dart';
 import '../../fake_native_assets_build_runner.dart';
 
 void main() {
@@ -73,7 +74,7 @@ void main() {
   });
 
   testUsingContext('NativeAssets defaults to ios archs if missing', () async {
-    await createPackageConfig(iosEnvironment);
+    writePackageConfigFile(directory: iosEnvironment.projectDir, mainLibName: 'my_app');
 
     iosEnvironment.defines.remove(kIosArchs);
 
@@ -90,7 +91,7 @@ void main() {
     'NativeAssets throws error if missing sdk root',
     overrides: <Type, Generator>{FeatureFlags: () => TestFeatureFlags(isNativeAssetsEnabled: true)},
     () async {
-      await createPackageConfig(iosEnvironment);
+      writePackageConfigFile(directory: iosEnvironment.projectDir, mainLibName: 'my_app');
 
       final FlutterNativeAssetsBuildRunner buildRunner = FakeFlutterNativeAssetsBuildRunner(
         packagesWithNativeAssetsResult: <String>['foo'],
@@ -116,7 +117,7 @@ void main() {
         FeatureFlags: () => TestFeatureFlags(isNativeAssetsEnabled: isNativeAssetsEnabled),
       },
       () async {
-        await createPackageConfig(iosEnvironment);
+        writePackageConfigFile(directory: iosEnvironment.projectDir, mainLibName: 'my_app');
 
         final FlutterNativeAssetsBuildRunner buildRunner = FakeFlutterNativeAssetsBuildRunner();
         await DartBuildForNative(buildRunner: buildRunner).build(iosEnvironment);
@@ -186,7 +187,7 @@ void main() {
       FeatureFlags: () => TestFeatureFlags(isNativeAssetsEnabled: true),
     },
     () async {
-      await createPackageConfig(iosEnvironment);
+      writePackageConfigFile(directory: iosEnvironment.projectDir, mainLibName: 'my_app');
 
       final List<CodeAsset> codeAssets = <CodeAsset>[
         CodeAsset(
@@ -252,7 +253,7 @@ void main() {
         FeatureFlags: () => TestFeatureFlags(isNativeAssetsEnabled: true),
       },
       () async {
-        await createPackageConfig(androidEnvironment);
+        writePackageConfigFile(directory: androidEnvironment.projectDir, mainLibName: 'my_app');
         await fileSystem.file('libfoo.so').create();
 
         final List<CodeAsset> codeAssets = <CodeAsset>[
@@ -279,11 +280,3 @@ void main() {
     );
   }
 }
-
-Future<void> createPackageConfig(Environment iosEnvironment) async {
-  final File packageConfig = iosEnvironment.projectDir
-      .childDirectory('.dart_tool')
-      .childFile('package_config.json');
-  await packageConfig.parent.create();
-  await packageConfig.create();
-}
diff --git a/packages/flutter_tools/test/general.shard/isolated/linux/native_assets_test.dart b/packages/flutter_tools/test/general.shard/isolated/linux/native_assets_test.dart
index ed54ae8d36..f1a2796c99 100644
--- a/packages/flutter_tools/test/general.shard/isolated/linux/native_assets_test.dart
+++ b/packages/flutter_tools/test/general.shard/isolated/linux/native_assets_test.dart
@@ -21,6 +21,7 @@ import 'package:package_config/package_config_types.dart';
 import '../../../src/common.dart';
 import '../../../src/context.dart';
 import '../../../src/fakes.dart';
+import '../../../src/package_config.dart';
 import '../fake_native_assets_build_runner.dart';
 
 void main() {
@@ -103,12 +104,10 @@ void main() {
       await fileSystem.file('/some/path/to/llvm-ar').create();
       await fileSystem.file('/some/path/to/ld.lld').create();
 
-      final File packageConfigFile = fileSystem
-          .directory(projectUri)
-          .childDirectory('.dart_tool')
-          .childFile('package_config.json');
-      await packageConfigFile.parent.create();
-      await packageConfigFile.create();
+      final File packageConfigFile = writePackageConfigFile(
+        directory: fileSystem.directory(projectUri),
+        mainLibName: 'my_app',
+      );
       final PackageConfig packageConfig = await loadPackageConfigWithLogging(
         packageConfigFile,
         logger: environment.logger,
diff --git a/packages/flutter_tools/test/general.shard/isolated/macos/native_assets_test.dart b/packages/flutter_tools/test/general.shard/isolated/macos/native_assets_test.dart
index 55d0b74268..e03f65fba3 100644
--- a/packages/flutter_tools/test/general.shard/isolated/macos/native_assets_test.dart
+++ b/packages/flutter_tools/test/general.shard/isolated/macos/native_assets_test.dart
@@ -21,6 +21,7 @@ import 'package:package_config/package_config_types.dart';
 import '../../../src/common.dart';
 import '../../../src/context.dart';
 import '../../../src/fakes.dart';
+import '../../../src/package_config.dart';
 import '../fake_native_assets_build_runner.dart';
 
 void main() {
@@ -388,12 +389,10 @@ InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault
         return;
       }
 
-      final File packageConfigFile = fileSystem
-          .directory(projectUri)
-          .childDirectory('.dart_tool')
-          .childFile('package_config.json');
-      await packageConfigFile.parent.create();
-      await packageConfigFile.create();
+      final File packageConfigFile = writePackageConfigFile(
+        directory: fileSystem.directory(projectUri),
+        mainLibName: 'my_app',
+      );
       final PackageConfig packageConfig = await loadPackageConfigWithLogging(
         packageConfigFile,
         logger: environment.logger,
diff --git a/packages/flutter_tools/test/general.shard/isolated/windows/native_assets_test.dart b/packages/flutter_tools/test/general.shard/isolated/windows/native_assets_test.dart
index 85e6b5df2f..36ab9f068f 100644
--- a/packages/flutter_tools/test/general.shard/isolated/windows/native_assets_test.dart
+++ b/packages/flutter_tools/test/general.shard/isolated/windows/native_assets_test.dart
@@ -22,6 +22,7 @@ import 'package:package_config/package_config_types.dart';
 import '../../../src/common.dart';
 import '../../../src/context.dart';
 import '../../../src/fakes.dart';
+import '../../../src/package_config.dart';
 import '../fake_native_assets_build_runner.dart';
 
 void main() {
@@ -76,13 +77,9 @@ void main() {
           ProcessManager: () => FakeProcessManager.empty(),
         },
         () async {
-          final File packageConfig = environment.projectDir
-              .childDirectory('.dart_tool')
-              .childFile('package_config.json');
+          writePackageConfigFile(directory: environment.projectDir, mainLibName: 'my_app');
           final Uri nonFlutterTesterAssetUri =
               environment.buildDir.childFile(InstallCodeAssets.nativeAssetsFilename).uri;
-          await packageConfig.parent.create();
-          await packageConfig.create();
           final File dylibAfterCompiling = fileSystem.file('bar.dll');
           // The mock doesn't create the file, so create it here.
           await dylibAfterCompiling.create();
@@ -255,12 +252,10 @@ void main() {
       );
       await msvcBinDir.create(recursive: true);
 
-      final File packageConfigFile = fileSystem
-          .directory(projectUri)
-          .childDirectory('.dart_tool')
-          .childFile('package_config.json');
-      await packageConfigFile.parent.create();
-      await packageConfigFile.create();
+      final File packageConfigFile = writePackageConfigFile(
+        directory: fileSystem.directory(projectUri),
+        mainLibName: 'my_app',
+      );
       final PackageConfig packageConfig = await loadPackageConfigWithLogging(
         packageConfigFile,
         logger: environment.logger,
diff --git a/packages/flutter_tools/test/general.shard/macos/cocoapod_utils_test.dart b/packages/flutter_tools/test/general.shard/macos/cocoapod_utils_test.dart
index 2c3ab180b2..80a7ab2635 100644
--- a/packages/flutter_tools/test/general.shard/macos/cocoapod_utils_test.dart
+++ b/packages/flutter_tools/test/general.shard/macos/cocoapod_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.
 
-import 'dart:convert';
-
 import 'package:file/file.dart';
 import 'package:file/memory.dart';
 import 'package:file_testing/file_testing.dart';
@@ -19,6 +17,7 @@ import 'package:test/fake.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fake_pub_deps.dart';
+import '../../src/package_config.dart';
 
 void main() {
   group('processPodsIfNeeded', () {
@@ -27,7 +26,11 @@ void main() {
     late BufferLogger logger;
 
     // Adds basic properties to the flutterProject and its subprojects.
-    void setUpProject(FakeFlutterProject flutterProject, MemoryFileSystem fileSystem) {
+    void setUpProject(
+      FakeFlutterProject flutterProject,
+      MemoryFileSystem fileSystem, {
+      List<String> pluginNames = const <String>[],
+    }) {
       flutterProject
         ..manifest = FakeFlutterManifest()
         ..directory = fileSystem.systemTempDirectory.childDirectory('app')
@@ -40,28 +43,11 @@ void main() {
         ..android = FakeAndroidProject()
         ..web = FakeWebProject()
         ..windows = FakeWindowsProject()
-        ..linux = FakeLinuxProject();
-      flutterProject.directory.childDirectory('.dart_tool').childFile('package_config.json')
-        ..createSync(recursive: true)
-        ..writeAsStringSync('''
-{
-  "packages": [],
-  "configVersion": 2
-}
-''');
-    }
+        ..linux = FakeLinuxProject()
+        ..packageConfig = flutterProject.directory
+            .childDirectory('.dart_tool')
+            .childFile('package_config.json');
 
-    setUp(() async {
-      fs = MemoryFileSystem.test();
-      cocoaPods = FakeCocoaPods();
-      logger = BufferLogger.test();
-    });
-
-    void createFakePlugins(
-      FlutterProject flutterProject,
-      FileSystem fileSystem,
-      List<String> pluginNames,
-    ) {
       const String pluginYamlTemplate = '''
       flutter:
         plugin:
@@ -73,36 +59,38 @@ void main() {
       ''';
 
       final Directory fakePubCache = fileSystem.systemTempDirectory.childDirectory('cache');
-      final File packageConfigFile = flutterProject.directory
-        .childDirectory('.dart_tool')
-        .childFile('package_config.json')..createSync(recursive: true);
-      final Map<String, Object?> packageConfig = <String, Object?>{
-        'packages': <Object?>[],
-        'configVersion': 2,
-      };
+
+      writePackageConfigFile(
+        directory: flutterProject.directory,
+        mainLibName: 'my_app',
+        packages: <String, String>{
+          for (final String plugin in pluginNames)
+            plugin: fakePubCache.childDirectory(plugin).uri.toString(),
+        },
+      );
+
       for (final String name in pluginNames) {
+        flutterProject.manifest.dependencies.add(name);
         final Directory pluginDirectory = fakePubCache.childDirectory(name);
-        (packageConfig['packages']! as List<Object?>).add(<String, Object?>{
-          'name': name,
-          'rootUri': pluginDirectory.uri.toString(),
-          'packageUri': 'lib/',
-        });
         pluginDirectory.childFile('pubspec.yaml')
           ..createSync(recursive: true)
           ..writeAsStringSync(pluginYamlTemplate.replaceAll('PLUGIN_CLASS', name));
       }
-
-      packageConfigFile.writeAsStringSync(jsonEncode(packageConfig));
     }
 
+    setUp(() async {
+      fs = MemoryFileSystem.test();
+      cocoaPods = FakeCocoaPods();
+      logger = BufferLogger.test();
+    });
+
     group('for iOS', () {
       group('using CocoaPods only', () {
         testUsingContext(
           'processes when there are plugins',
           () async {
             final FakeFlutterProject flutterProject = FakeFlutterProject();
-            setUpProject(flutterProject, fs);
-            createFakePlugins(flutterProject, fs, <String>['plugin_one', 'plugin_two']);
+            setUpProject(flutterProject, fs, pluginNames: <String>['plugin_one', 'plugin_two']);
 
             await processPodsIfNeeded(
               flutterProject.ios,
@@ -191,8 +179,7 @@ void main() {
           'processes if podfile exists',
           () async {
             final FakeFlutterProject flutterProject = FakeFlutterProject();
-            setUpProject(flutterProject, fs);
-            createFakePlugins(flutterProject, fs, <String>['plugin_one', 'plugin_two']);
+            setUpProject(flutterProject, fs, pluginNames: <String>['plugin_one', 'plugin_two']);
             flutterProject.ios.usesSwiftPackageManager = true;
             flutterProject.ios.podfile.createSync(recursive: true);
 
@@ -215,8 +202,7 @@ void main() {
           'skip if podfile does not exists',
           () async {
             final FakeFlutterProject flutterProject = FakeFlutterProject();
-            setUpProject(flutterProject, fs);
-            createFakePlugins(flutterProject, fs, <String>['plugin_one', 'plugin_two']);
+            setUpProject(flutterProject, fs, pluginNames: <String>['plugin_one', 'plugin_two']);
             flutterProject.ios.usesSwiftPackageManager = true;
 
             await processPodsIfNeeded(
@@ -237,8 +223,7 @@ void main() {
           'process if podfile does not exists but forceCocoaPodsOnly is true',
           () async {
             final FakeFlutterProject flutterProject = FakeFlutterProject();
-            setUpProject(flutterProject, fs);
-            createFakePlugins(flutterProject, fs, <String>['plugin_one', 'plugin_two']);
+            setUpProject(flutterProject, fs, pluginNames: <String>['plugin_one', 'plugin_two']);
             flutterProject.ios.usesSwiftPackageManager = true;
             final File generatedManifestFile = flutterProject.ios.flutterPluginSwiftPackageManifest;
             generatedManifestFile.createSync(recursive: true);
@@ -277,8 +262,7 @@ void main() {
           'processes when there are plugins',
           () async {
             final FakeFlutterProject flutterProject = FakeFlutterProject();
-            setUpProject(flutterProject, fs);
-            createFakePlugins(flutterProject, fs, <String>['plugin_one', 'plugin_two']);
+            setUpProject(flutterProject, fs, pluginNames: <String>['plugin_one', 'plugin_two']);
 
             await processPodsIfNeeded(
               flutterProject.macos,
@@ -367,8 +351,7 @@ void main() {
           'processes if podfile exists',
           () async {
             final FakeFlutterProject flutterProject = FakeFlutterProject();
-            setUpProject(flutterProject, fs);
-            createFakePlugins(flutterProject, fs, <String>['plugin_one', 'plugin_two']);
+            setUpProject(flutterProject, fs, pluginNames: <String>['plugin_one', 'plugin_two']);
             flutterProject.macos.usesSwiftPackageManager = true;
             flutterProject.macos.podfile.createSync(recursive: true);
 
@@ -391,8 +374,7 @@ void main() {
           'skip if podfile does not exists',
           () async {
             final FakeFlutterProject flutterProject = FakeFlutterProject();
-            setUpProject(flutterProject, fs);
-            createFakePlugins(flutterProject, fs, <String>['plugin_one', 'plugin_two']);
+            setUpProject(flutterProject, fs, pluginNames: <String>['plugin_one', 'plugin_two']);
             flutterProject.macos.usesSwiftPackageManager = true;
 
             await processPodsIfNeeded(
@@ -413,8 +395,7 @@ void main() {
           'process if podfile does not exists but forceCocoaPodsOnly is true',
           () async {
             final FakeFlutterProject flutterProject = FakeFlutterProject();
-            setUpProject(flutterProject, fs);
-            createFakePlugins(flutterProject, fs, <String>['plugin_one', 'plugin_two']);
+            setUpProject(flutterProject, fs, pluginNames: <String>['plugin_one', 'plugin_two']);
             flutterProject.macos.usesSwiftPackageManager = true;
             final File generatedManifestFile =
                 flutterProject.macos.flutterPluginSwiftPackageManifest;
@@ -489,6 +470,9 @@ class FakeFlutterProject extends Fake implements FlutterProject {
 
   @override
   late WindowsProject windows;
+
+  @override
+  late File packageConfig;
 }
 
 class FakeMacOSProject extends Fake implements MacOSProject {
diff --git a/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart b/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart
index 63f4f4eceb..2cea1d9984 100644
--- a/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart
+++ b/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart
@@ -23,6 +23,7 @@ import '../../src/context.dart';
 import '../../src/fake_process_manager.dart';
 import '../../src/fake_pub_deps.dart';
 import '../../src/fakes.dart';
+import '../../src/package_config.dart';
 
 enum _StdioStream { stdout, stderr }
 
@@ -58,10 +59,19 @@ void main() {
   }
 
   FlutterProject setupProjectUnderTest() {
+    fileSystem.directory('project').childFile('pubspec.yaml')
+      ..createSync(recursive: true)
+      ..writeAsStringSync('''
+name: my_app
+environement:
+  sdk: '^3.5.0'
+''');
+
     // This needs to be run within testWithoutContext and not setUp since FlutterProject uses context.
     final FlutterProject projectUnderTest = FlutterProject.fromDirectory(
       fileSystem.directory('project'),
     );
+    writePackageConfigFile(directory: projectUnderTest.directory, mainLibName: 'my_app');
     projectUnderTest.ios.xcodeProject.createSync(recursive: true);
     projectUnderTest.macos.xcodeProject.createSync(recursive: true);
     return projectUnderTest;
@@ -389,11 +399,6 @@ void main() {
       'includes Pod config in xcconfig files, if the user manually added Pod dependencies without using Flutter plugins',
       () async {
         final FlutterProject projectUnderTest = setupProjectUnderTest();
-        final File packageConfigFile = fileSystem.file(
-          fileSystem.path.join('project', '.dart_tool', 'package_config.json'),
-        );
-        packageConfigFile.createSync(recursive: true);
-        packageConfigFile.writeAsStringSync('{"configVersion":2,"packages":[]}');
         projectUnderTest.ios.podfile
           ..createSync()
           ..writeAsStringSync('Custom Podfile');
diff --git a/packages/flutter_tools/test/general.shard/plugins_test.dart b/packages/flutter_tools/test/general.shard/plugins_test.dart
index 658cf1943d..b3669ec394 100644
--- a/packages/flutter_tools/test/general.shard/plugins_test.dart
+++ b/packages/flutter_tools/test/general.shard/plugins_test.dart
@@ -33,6 +33,7 @@ import '../src/common.dart';
 import '../src/context.dart';
 import '../src/fake_pub_deps.dart';
 import '../src/fakes.dart' hide FakeOperatingSystemUtils;
+import '../src/package_config.dart';
 import '../src/pubspec_schema.dart';
 
 /// Information for a platform entry in the 'platforms' section of a plugin's
@@ -197,14 +198,7 @@ void main() {
 
       // Add basic properties to the Flutter project and subprojects
       setUpProject(fs);
-      flutterProject.directory.childDirectory('.dart_tool').childFile('package_config.json')
-        ..createSync(recursive: true)
-        ..writeAsStringSync('''
-{
-  "packages": [],
-  "configVersion": 2
-}
-''');
+      writePackageConfigFile(directory: flutterProject.directory, mainLibName: 'my_app');
     });
 
     void addToPackageConfig(String name, Directory packageDir) {
@@ -254,14 +248,7 @@ void main() {
 
       final List<Directory> directories = <Directory>[];
       final Directory fakePubCache = fileSystem.systemTempDirectory.childDirectory('cache');
-      flutterProject.directory.childDirectory('.dart_tool').childFile('package_config.json')
-        ..createSync(recursive: true)
-        ..writeAsStringSync('''
-{
-  "packages": [],
-  "configVersion": 2
-}
-''');
+      writePackageConfigFile(directory: flutterProject.directory, mainLibName: 'my_app');
       for (final String nameOrPath in pluginNamesOrPaths) {
         final String name = fileSystem.path.basename(nameOrPath);
         final Directory pluginDirectory =
@@ -1317,7 +1304,7 @@ flutter:
 
             final FlutterManifest manifest =
                 FlutterManifest.createFromString('''
-name: test
+name: my_app
 version: 1.0.0
 
 dependencies:
@@ -1590,7 +1577,7 @@ flutter:
 
           final FlutterManifest manifest =
               FlutterManifest.createFromString('''
-name: test
+name: my_app
 version: 1.0.0
 
 dependencies:
@@ -1663,7 +1650,7 @@ flutter:
 
           final FlutterManifest manifest =
               FlutterManifest.createFromString('''
-name: test
+name: my_app
 version: 1.0.0
 
 dependencies:
@@ -2445,10 +2432,7 @@ flutter:
           ..flutterPluginsDependenciesFile = dependenciesFile
           ..windows = windowsProject;
 
-        flutterProject.directory
-            .childDirectory('.dart_tool')
-            .childFile('package_config.json')
-            .createSync(recursive: true);
+        writePackageConfigFile(directory: flutterProject.directory, mainLibName: 'my_app');
 
         const String dependenciesFileContents = r'''
 {
@@ -2817,10 +2801,7 @@ flutter:
         )
         ..windows = windowsProject;
 
-      flutterProject.directory
-          .childDirectory('.dart_tool')
-          .childFile('package_config.json')
-          .createSync(recursive: true);
+      writePackageConfigFile(directory: flutterProject.directory, mainLibName: 'my_app');
 
       createPluginSymlinks(
         flutterProject,
diff --git a/packages/flutter_tools/test/general.shard/project_test.dart b/packages/flutter_tools/test/general.shard/project_test.dart
index f8de74eda8..570f30f995 100644
--- a/packages/flutter_tools/test/general.shard/project_test.dart
+++ b/packages/flutter_tools/test/general.shard/project_test.dart
@@ -29,6 +29,7 @@ import '../src/common.dart';
 import '../src/context.dart';
 import '../src/fake_pub_deps.dart';
 import '../src/fakes.dart';
+import '../src/package_config.dart';
 
 void main() {
   // TODO(matanlurey): Remove after `explicit-package-dependencies` is enabled by default.
@@ -1825,9 +1826,7 @@ Future<FlutterProject> someProject({
   bool includePubspec = false,
 }) async {
   final Directory directory = globals.fs.directory('some_project');
-  directory.childDirectory('.dart_tool').childFile('package_config.json')
-    ..createSync(recursive: true)
-    ..writeAsStringSync('{"configVersion":2,"packages":[]}');
+  writePackageConfigFile(directory: globals.fs.currentDirectory, mainLibName: 'hello');
   if (includePubspec) {
     directory.childFile('pubspec.yaml')
       ..createSync(recursive: true)
@@ -1926,9 +1925,7 @@ class MyPlugin extends FluttPlugin { /* ... */ }
 
 Future<FlutterProject> aModuleProject() async {
   final Directory directory = globals.fs.directory('module_project');
-  directory.childDirectory('.dart_tool').childFile('package_config.json')
-    ..createSync(recursive: true)
-    ..writeAsStringSync('{"configVersion":2,"packages":[]}');
+  writePackageConfigFile(mainLibName: 'my_module', directory: directory);
   directory.childFile('pubspec.yaml').writeAsStringSync('''
 name: my_module
 flutter:
@@ -1952,9 +1949,6 @@ void _testInMemory(
 }) {
   Cache.flutterRoot = getFlutterRoot();
   final FileSystem testFileSystem = fileSystem ?? getFileSystemForPlatform();
-  testFileSystem.directory('.dart_tool').childFile('package_config.json')
-    ..createSync(recursive: true)
-    ..writeAsStringSync('{"configVersion":2,"packages":[]}');
   // Transfer needed parts of the Flutter installation folder
   // to the in-memory file system used during testing.
   final Logger logger = BufferLogger.test();
@@ -1982,27 +1976,17 @@ void _testInMemory(
     testFileSystem,
   );
   // Set up enough of the packages to satisfy the templating code.
-  final File packagesFile = testFileSystem
-      .directory(Cache.flutterRoot)
-      .childDirectory('packages')
-      .childDirectory('flutter_tools')
-      .childDirectory('.dart_tool')
-      .childFile('package_config.json');
   final Directory dummyTemplateImagesDirectory = testFileSystem.directory(Cache.flutterRoot).parent;
   dummyTemplateImagesDirectory.createSync(recursive: true);
-  packagesFile.createSync(recursive: true);
-  packagesFile.writeAsStringSync(
-    json.encode(<String, Object>{
-      'configVersion': 2,
-      'packages': <Object>[
-        <String, Object>{
-          'name': 'flutter_template_images',
-          'rootUri': dummyTemplateImagesDirectory.uri.toString(),
-          'packageUri': 'lib/',
-          'languageVersion': '2.6',
-        },
-      ],
-    }),
+  writePackageConfigFile(
+    directory: testFileSystem
+        .directory(Cache.flutterRoot)
+        .childDirectory('packages')
+        .childDirectory('flutter_tools'),
+    mainLibName: 'my_app',
+    packages: <String, String>{
+      'flutter_template_images': dummyTemplateImagesDirectory.uri.toString(),
+    },
   );
 
   testUsingContext(
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 d292bc1ea4..bcc9d2f80c 100644
--- a/packages/flutter_tools/test/general.shard/resident_runner_test.dart
+++ b/packages/flutter_tools/test/general.shard/resident_runner_test.dart
@@ -36,6 +36,7 @@ import '../src/context.dart';
 import '../src/fake_pub_deps.dart';
 import '../src/fake_vm_services.dart';
 import '../src/fakes.dart';
+import '../src/package_config.dart';
 import '../src/testbed.dart';
 import 'resident_runner_helpers.dart';
 
@@ -1087,26 +1088,18 @@ void main() {
   }
 }''');
         globals.fs.file('l10n.yaml').createSync();
-        globals.fs.file('pubspec.yaml').writeAsStringSync('flutter:\n  generate: true\n');
+        globals.fs.file('pubspec.yaml').writeAsStringSync('''
+name: my_app
+flutter:
+  generate: true''');
 
         // Create necessary files for [DartPluginRegistrantTarget]
-        final File packageConfig = globals.fs
-            .directory('.dart_tool')
-            .childFile('package_config.json');
-        packageConfig.createSync(recursive: true);
-        packageConfig.writeAsStringSync('''
-{
-  "configVersion": 2,
-  "packages": [
-    {
-      "name": "path_provider_linux",
-      "rootUri": "../../../path_provider_linux",
-      "packageUri": "lib/",
-      "languageVersion": "2.12"
-    }
-  ]
-}
-''');
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'path_provider_linux': 'path_provider_linux'},
+        );
+
         // Start from an empty dart_plugin_registrant.dart file.
         globals.fs
             .directory('.dart_tool')
@@ -1141,6 +1134,7 @@ void main() {
 }''');
         globals.fs.file('l10n.yaml').createSync();
         globals.fs.file('pubspec.yaml').writeAsStringSync('''
+name: my_app
 flutter:
   generate: true
 
@@ -1152,23 +1146,12 @@ dependencies:
 
         // Create necessary files for [DartPluginRegistrantTarget], including a
         // plugin that will trigger generation.
-        final File packageConfig = globals.fs
-            .directory('.dart_tool')
-            .childFile('package_config.json');
-        packageConfig.createSync(recursive: true);
-        packageConfig.writeAsStringSync('''
-{
-  "configVersion": 2,
-  "packages": [
-    {
-      "name": "path_provider_linux",
-      "rootUri": "../path_provider_linux",
-      "packageUri": "lib/",
-      "languageVersion": "2.12"
-    }
-  ]
-}
-''');
+        writePackageConfigFile(
+          directory: globals.fs.currentDirectory,
+          mainLibName: 'my_app',
+          packages: <String, String>{'path_provider_linux': 'path_provider_linux'},
+        );
+
         final Directory fakePluginDir = globals.fs.directory('path_provider_linux');
         final File pluginPubspec = fakePluginDir.childFile('pubspec.yaml');
         pluginPubspec.createSync(recursive: true);
diff --git a/packages/flutter_tools/test/general.shard/resident_web_runner_cold_test.dart b/packages/flutter_tools/test/general.shard/resident_web_runner_cold_test.dart
index 44f0d93604..360c02d044 100644
--- a/packages/flutter_tools/test/general.shard/resident_web_runner_cold_test.dart
+++ b/packages/flutter_tools/test/general.shard/resident_web_runner_cold_test.dart
@@ -28,6 +28,7 @@ import '../src/common.dart';
 import '../src/context.dart';
 import '../src/fake_pub_deps.dart';
 import '../src/fakes.dart';
+import '../src/package_config.dart';
 import '../src/test_build_system.dart';
 
 void main() {
@@ -48,8 +49,11 @@ void main() {
     mockFlutterDevice = FakeFlutterDevice(mockWebDevice);
     mockFlutterDevice._devFS = mockWebDevFS;
 
-    fileSystem.directory('.dart_tool').childFile('package_config.json').createSync(recursive: true);
-    fileSystem.file('pubspec.yaml').createSync();
+    fileSystem.file('pubspec.yaml').writeAsStringSync('''
+name: my_app
+''');
+
+    writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
     fileSystem.file(fileSystem.path.join('lib', 'main.dart')).createSync(recursive: true);
     fileSystem.file(fileSystem.path.join('web', 'index.html')).createSync(recursive: true);
   });
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 f1ccfd1ee5..cf87025692 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
@@ -45,6 +45,7 @@ import '../src/fake_process_manager.dart';
 import '../src/fake_pub_deps.dart';
 import '../src/fake_vm_services.dart';
 import '../src/fakes.dart' as test_fakes;
+import '../src/package_config.dart';
 
 const List<VmServiceExpectation> kAttachLogExpectations = <VmServiceExpectation>[
   FakeVmServiceRequest(method: 'streamListen', args: <String, Object>{'streamId': 'Stdout'}),
@@ -113,7 +114,10 @@ void main() {
           .._devFS = webDevFS
           ..device = mockDevice
           ..generator = residentCompiler;
-    fileSystem.directory('.dart_tool').childFile('package_config.json').createSync(recursive: true);
+    fileSystem.file('pubspec.yaml').writeAsStringSync('''
+name: my_app
+''');
+    writePackageConfigFile(directory: fileSystem.currentDirectory, mainLibName: 'my_app');
     fakeAnalytics = getInitializedFakeAnalyticsInstance(
       fs: fileSystem,
       fakeFlutterVersion: test_fakes.FakeFlutterVersion(),
@@ -1381,24 +1385,15 @@ void main() {
 }''');
       globals.fs.file('l10n.yaml').createSync();
       globals.fs.file('pubspec.yaml').writeAsStringSync('''
+name: my_app
 flutter:
   generate: true
 ''');
-      globals.fs.directory('.dart_tool').childFile('package_config.json')
-        ..createSync(recursive: true)
-        ..writeAsStringSync('''
-{
-  "configVersion": 2,
-  "packages": [
-    {
-      "name": "path_provider_linux",
-      "rootUri": "../../../path_provider_linux",
-      "packageUri": "lib/",
-      "languageVersion": "2.12"
-    }
-  ]
-}
-''');
+      writePackageConfigFile(
+        directory: globals.fs.currentDirectory,
+        mainLibName: 'my_app',
+        packages: <String, String>{'path_provider_linux': '../../path_provider_linux'},
+      );
       expect(await residentWebRunner.run(), 0);
       final File generatedLocalizationsFile = globals.fs
           .directory('lib')
@@ -1422,23 +1417,12 @@ flutter:
     'Does not generate dart_plugin_registrant.dart',
     () async {
       // Create necessary files for [DartPluginRegistrantTarget]
-      final File packageConfig = globals.fs
-          .directory('.dart_tool')
-          .childFile('package_config.json');
-      packageConfig.createSync(recursive: true);
-      packageConfig.writeAsStringSync('''
-{
-  "configVersion": 2,
-  "packages": [
-    {
-      "name": "path_provider_linux",
-      "rootUri": "../../../path_provider_linux",
-      "packageUri": "lib/",
-      "languageVersion": "2.12"
-    }
-  ]
-}
-''');
+      writePackageConfigFile(
+        directory: globals.fs.currentDirectory,
+        mainLibName: 'my_app',
+        packages: <String, String>{'path_provider_linux': '../../path_provider_linux'},
+      );
+
       // Start with a dart_plugin_registrant.dart file.
       globals.fs
           .directory('.dart_tool')
diff --git a/packages/flutter_tools/test/general.shard/test/test_compiler_test.dart b/packages/flutter_tools/test/general.shard/test/test_compiler_test.dart
index 04201bca63..743f534bcb 100644
--- a/packages/flutter_tools/test/general.shard/test/test_compiler_test.dart
+++ b/packages/flutter_tools/test/general.shard/test/test_compiler_test.dart
@@ -22,6 +22,7 @@ import '../../src/context.dart';
 import '../../src/fake_pub_deps.dart';
 import '../../src/fakes.dart';
 import '../../src/logging_logger.dart';
+import '../../src/package_config.dart';
 
 final Platform linuxPlatform = FakePlatform(environment: <String, String>{});
 
@@ -46,9 +47,13 @@ void main() {
 
   setUp(() {
     fileSystem = MemoryFileSystem.test();
-    fileSystem.file('pubspec.yaml').createSync();
+    fileSystem.file('pubspec.yaml')
+      ..createSync()
+      ..writeAsStringSync('''
+name: foo
+''');
     fileSystem.file('test/foo.dart').createSync(recursive: true);
-    fileSystem.directory('.dart_tool').childFile('package_config.json').createSync(recursive: true);
+    writePackageConfigFile(mainLibName: 'foo', directory: fileSystem.currentDirectory);
     residentCompiler = FakeResidentCompiler(fileSystem);
     logger = LoggingLogger();
   });
@@ -216,20 +221,11 @@ dependencies:
     sdk: flutter
   a_plugin: 1.0.0
 ''');
-      fileSystem.directory('.dart_tool').childFile('package_config.json')
-        ..createSync(recursive: true)
-        ..writeAsStringSync('''
-{
-  "configVersion": 2,
-  "packages": [
-    {
-      "name": "a_plugin",
-      "rootUri": "/a_plugin/",
-      "packageUri": "lib/"
-    }
-  ]
-}
-''');
+      writePackageConfigFile(
+        directory: fileSystem.currentDirectory,
+        mainLibName: 'foo',
+        packages: <String, String>{'a_plugin': '/a_plugin'},
+      );
       fakeDartPlugin.childFile('pubspec.yaml')
         ..createSync(recursive: true)
         ..writeAsStringSync('''
diff --git a/packages/flutter_tools/test/general.shard/web/compile_web_test.dart b/packages/flutter_tools/test/general.shard/web/compile_web_test.dart
index 62acb43837..d48e513deb 100644
--- a/packages/flutter_tools/test/general.shard/web/compile_web_test.dart
+++ b/packages/flutter_tools/test/general.shard/web/compile_web_test.dart
@@ -19,6 +19,7 @@ import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fake_pub_deps.dart';
 import '../../src/fakes.dart';
+import '../../src/package_config.dart';
 import '../../src/test_build_system.dart';
 
 void main() {
@@ -48,10 +49,16 @@ void main() {
       fs: fileSystem,
       fakeFlutterVersion: flutterVersion,
     );
+    fileSystem.currentDirectory.childFile('pubspec.yaml')
+      ..createSync(recursive: true)
+      ..writeAsStringSync('''
+name: my_app
+environement:
+  sdk: '^3.5.0'
+''');
 
     flutterProject = FlutterProject.fromDirectoryTest(fileSystem.currentDirectory);
-
-    fileSystem.directory('.dart_tool').childFile('package_config.json').createSync(recursive: true);
+    writePackageConfigFile(directory: flutterProject.directory, mainLibName: 'my_app');
   });
 
   testUsingContext(
diff --git a/packages/flutter_tools/test/general.shard/web/migrations/scrub_generated_plugin_registrant_test.dart b/packages/flutter_tools/test/general.shard/web/migrations/scrub_generated_plugin_registrant_test.dart
index eb59a200b9..e83eb57a41 100644
--- a/packages/flutter_tools/test/general.shard/web/migrations/scrub_generated_plugin_registrant_test.dart
+++ b/packages/flutter_tools/test/general.shard/web/migrations/scrub_generated_plugin_registrant_test.dart
@@ -14,6 +14,7 @@ import 'package:flutter_tools/src/features.dart';
 import '../../../src/context.dart'; // legacy
 import '../../../src/fake_pub_deps.dart';
 import '../../../src/fakes.dart';
+import '../../../src/package_config.dart';
 import '../../../src/test_build_system.dart';
 import '../../../src/test_flutter_command_runner.dart'; // legacy
 
@@ -284,4 +285,9 @@ flutter:
 class UrlLauncherPlugin {}
 ''');
   fileSystem.file(fileSystem.path.join('lib', 'main.dart')).writeAsStringSync('void main() { }');
+  writePackageConfigFile(
+    directory: fileSystem.currentDirectory,
+    mainLibName: 'foo',
+    packages: <String, String>{'bar': 'bar'},
+  );
 }
diff --git a/packages/flutter_tools/test/integration.shard/test_data/project.dart b/packages/flutter_tools/test/integration.shard/test_data/project.dart
index 34e1389b97..2f192ff1f2 100644
--- a/packages/flutter_tools/test/integration.shard/test_data/project.dart
+++ b/packages/flutter_tools/test/integration.shard/test_data/project.dart
@@ -4,6 +4,7 @@
 
 import 'package:file/file.dart';
 
+import '../../src/package_config.dart';
 import '../test_utils.dart';
 import 'deferred_components_config.dart';
 
@@ -66,7 +67,7 @@ abstract class Project {
     writeFile(fileSystem.path.join(dir.path, 'web', 'index.html'), indexHtml);
     writeFile(fileSystem.path.join(dir.path, 'web', 'flutter.js'), '');
     writeFile(fileSystem.path.join(dir.path, 'web', 'flutter_service_worker.js'), '');
-    writePackageConfig(dir.path);
+    writePackageConfigFile(directory: dir, mainLibName: 'test');
     await getPackages(dir.path);
   }
 
diff --git a/packages/flutter_tools/test/integration.shard/test_utils.dart b/packages/flutter_tools/test/integration.shard/test_utils.dart
index 3dd34d54d3..323103c4c8 100644
--- a/packages/flutter_tools/test/integration.shard/test_utils.dart
+++ b/packages/flutter_tools/test/integration.shard/test_utils.dart
@@ -56,21 +56,6 @@ void writeBytesFile(String path, List<int> content) {
     ..writeAsBytesSync(content, flush: true);
 }
 
-void writePackageConfig(String folder) {
-  writeFile(fileSystem.path.join(folder, '.dart_tool', 'package_config.json'), '''
-{
-  "configVersion": 2,
-  "packages": [
-    {
-      "name": "test",
-      "rootUri": "fileSystem.currentDirectory.path"
-      "packageUri": "lib/",
-    }
-  ]
-}
-''');
-}
-
 Future<void> getPackages(String folder) async {
   final List<String> command = <String>[
     fileSystem.path.join(getFlutterRoot(), 'bin', 'flutter'),
diff --git a/packages/flutter_tools/test/src/package_config.dart b/packages/flutter_tools/test/src/package_config.dart
new file mode 100644
index 0000000000..50ee28f5b4
--- /dev/null
+++ b/packages/flutter_tools/test/src/package_config.dart
@@ -0,0 +1,47 @@
+// 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.
+
+import 'dart:convert';
+import 'package:file/file.dart';
+
+/// Writes a `.dart_tool/package_config.json` file at [directory].
+///
+/// If directory is not specified, it will be `globals.fs.currentDirectory`;
+///
+/// It will contain a package entry for [mainLibName] with `rootUri` at
+/// [directory].
+///
+/// [otherLibs] maps other package names to their `rootUri` relative to `directory`.
+///
+/// Returns the `File` Object representing the package config.
+File writePackageConfigFile({
+  required Directory directory,
+  required String mainLibName,
+  Map<String, String> packages = const <String, String>{},
+  Map<String, String> languageVersions = const <String, String>{},
+}) {
+  return directory.childDirectory('.dart_tool').childFile('package_config.json')
+    ..createSync(recursive: true)
+    ..writeAsStringSync(
+      json.encode(<String, Object?>{
+        'packages': <Object>[
+          <String, Object?>{
+            'name': mainLibName,
+            'rootUri': '../',
+            'packageUri': 'lib/',
+            'languageVersion': languageVersions[mainLibName] ?? '3.7',
+          },
+          ...packages.entries.map(
+            (MapEntry<String, String> entry) => <String, Object?>{
+              'name': entry.key,
+              'rootUri': Uri.parse('../').resolve(entry.value).toString(),
+              'packageUri': 'lib/',
+              'languageVersion': languageVersions[entry.key] ?? '3.7',
+            },
+          ),
+        ],
+        'configVersion': 2,
+      }),
+    );
+}