[flutter_tools] ensure pub get can run from partially valid state (#74249)

packages/flutter_tools/lib/src/commands/packages.dart

@@ -76,6 +76,8 @@ class PackagesGetCommand extends FlutterCommand {
     return '${runner.executableName} pub $name [<target directory>]';
   }
 
+  /// The pub packages usage values are incorrect since these are calculated/sent
+  /// before pub get completes. This needs to be performed after dependency resolution.
   @override
   Future<Map<CustomDimensions, String>> get usageValues async {
     final Map<CustomDimensions, String> usageValues = <CustomDimensions, String>{};
@@ -85,9 +87,14 @@ class PackagesGetCommand extends FlutterCommand {
       return usageValues;
     }
     final FlutterProject rootProject = FlutterProject.fromPath(target);
-    final bool hasPlugins = rootProject.flutterPluginsDependenciesFile.existsSync();
+    // Do not send plugin analytics if pub has not run before.
+    final bool hasPlugins = rootProject.flutterPluginsDependenciesFile.existsSync()
+      && rootProject.packagesFile.existsSync()
+      && rootProject.packageConfigFile.existsSync();
     if (hasPlugins) {
-      final List<Plugin> plugins = await findPlugins(rootProject);
+      // Do not fail pub get if package config files are invalid before pub has
+      // had a chance to run.
+      final List<Plugin> plugins = await findPlugins(rootProject, throwOnError: false);
       usageValues[CustomDimensions.commandPackagesNumberPlugins] = plugins.length.toString();
     } else {
       usageValues[CustomDimensions.commandPackagesNumberPlugins] = '0';

packages/flutter_tools/lib/src/plugins.dart

@@ -345,7 +345,7 @@ Plugin _pluginFromPackage(String name, Uri packageRoot) {
   );
 }
 
-Future<List<Plugin>> findPlugins(FlutterProject project) async {
+Future<List<Plugin>> findPlugins(FlutterProject project, { bool throwOnError = true}) async {
   final List<Plugin> plugins = <Plugin>[];
   final String packagesFile = globals.fs.path.join(
     project.directory.path,
@@ -354,6 +354,7 @@ Future<List<Plugin>> findPlugins(FlutterProject project) async {
   final PackageConfig packageConfig = await loadPackageConfigWithLogging(
     globals.fs.file(packagesFile),
     logger: globals.logger,
+    throwOnError: throwOnError,
   );
   for (final Package package in packageConfig.packages) {
     final Uri packageRoot = package.packageUriRoot.resolve('..');

packages/flutter_tools/lib/src/project.dart

@@ -162,6 +162,12 @@ class FlutterProject {
   /// The `.packages` file of this project.
   File get packagesFile => directory.childFile('.packages');
 
+  /// The `package_config.json` file of the project.
+  ///
+  /// This is the replacement for .packages which contains language
+  /// version information.
+  File get packageConfigFile => directory.childDirectory('.dart_tool').childFile('package_config.json');
+
   /// The `.metadata` file of this project.
   File get metadataFile => directory.childFile('.metadata');
 

packages/flutter_tools/test/commands.shard/hermetic/pub_get_test.dart

@@ -0,0 +1,101 @@
+// 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 'package:args/command_runner.dart';
+import 'package:file/memory.dart';
+import 'package:flutter_tools/src/base/file_system.dart';
+import 'package:flutter_tools/src/cache.dart';
+import 'package:flutter_tools/src/commands/packages.dart';
+import 'package:flutter_tools/src/dart/pub.dart';
+import 'package:flutter_tools/src/reporting/reporting.dart';
+import 'package:meta/meta.dart';
+import 'package:test/fake.dart';
+
+import '../../src/common.dart';
+import '../../src/context.dart';
+
+void main() {
+  FileSystem fileSystem;
+  FakePub pub;
+
+  setUp(() {
+    Cache.disableLocking();
+    fileSystem = MemoryFileSystem.test();
+    pub = FakePub(fileSystem);
+  });
+
+  tearDown(() {
+    Cache.enableLocking();
+  });
+
+  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('.flutter-plugins').createSync();
+    fileSystem.currentDirectory.childFile('.flutter-plugins-dependencies').createSync();
+
+    final PackagesGetCommand command = PackagesGetCommand('get', false);
+    final CommandRunner<void> commandRunner = createTestCommandRunner(command);
+
+    await commandRunner.run(<String>['get']);
+
+    expect(await command.usageValues, <CustomDimensions, Object>{
+      CustomDimensions.commandPackagesNumberPlugins: '0',
+      CustomDimensions.commandPackagesProjectModule: 'false',
+      CustomDimensions.commandPackagesAndroidEmbeddingVersion: 'v1'
+    });
+  }, overrides: <Type, Generator>{
+    Pub: () => pub,
+    ProcessManager: () => FakeProcessManager.any(),
+    FileSystem: () => fileSystem,
+  });
+
+  testUsingContext('pub get usage values are resilient to poorly formatted package config before "pub get"', () async {
+    fileSystem.currentDirectory.childFile('pubspec.yaml').createSync();
+    fileSystem.currentDirectory.childFile('.flutter-plugins').createSync();
+    fileSystem.currentDirectory.childFile('.flutter-plugins-dependencies').createSync();
+    fileSystem.currentDirectory.childFile('.packages').writeAsBytesSync(<int>[0]);
+    fileSystem.currentDirectory.childFile('.dart_tool/package_config.json')
+      ..createSync(recursive: true)
+      ..writeAsBytesSync(<int>[0]);
+
+    final PackagesGetCommand command = PackagesGetCommand('get', false);
+    final CommandRunner<void> commandRunner = createTestCommandRunner(command);
+
+    await commandRunner.run(<String>['get']);
+
+    expect(await command.usageValues, <CustomDimensions, Object>{
+      CustomDimensions.commandPackagesNumberPlugins: '0',
+      CustomDimensions.commandPackagesProjectModule: 'false',
+      CustomDimensions.commandPackagesAndroidEmbeddingVersion: 'v1'
+    });
+  }, overrides: <Type, Generator>{
+    Pub: () => pub,
+    ProcessManager: () => FakeProcessManager.any(),
+    FileSystem: () => fileSystem,
+  });
+}
+
+class FakePub extends Fake implements Pub {
+  FakePub(this.fileSystem);
+
+  final FileSystem fileSystem;
+
+  @override
+  Future<void> get({
+    @required PubContext context,
+    String directory,
+    bool skipIfAbsent = false,
+    bool upgrade = false,
+    bool offline = false,
+    bool generateSyntheticPackage = false,
+    String flutterRootOverride,
+    bool checkUpToDate = false,
+  }) async {
+    fileSystem.currentDirectory
+      .childDirectory('.dart_tool')
+      .childFile('package_config.json')
+      ..createSync(recursive: true)
+      ..writeAsStringSync('{"configVersion":2,"packages":[]}');
+  }
+}

packages/flutter_tools/test/integration.shard/migrate_test.dart

@@ -8,10 +8,10 @@ import 'package:flutter_tools/src/base/io.dart';
 import '../src/common.dart';
 import 'test_utils.dart';
 
-/// Verifies that `dart migrate` will run successfuly on the default `flutter create`
+/// Verifies that `dart migrate` will run successfully on the default `flutter create`
 /// template.
 void main() {
-  testWithoutContext('dart migrate succeedes on flutter create template', () async {
+  testWithoutContext('dart migrate succeeds on flutter create template', () async {
     final String flutterBin = fileSystem.path.join(getFlutterRoot(), 'bin', platform.isWindows ? 'flutter.bat' : 'flutter');
     final String dartBin = fileSystem.path.join(getFlutterRoot(), 'bin', platform.isWindows ? 'dart.bat' : 'dart');