Begin migrating tools to NNBD (flutter#3891)

- Updates dependencies to null-safe versions
- Migrates common.dart (which doesn't depend on anything)
- Migrates common_tests.dart and its one dependency, utils.dart
- Adds build_runner for Mockito mock generation
- Adds a new utility methods for getting arguments that handle both the casting and the removal of nullability to address a common problematic pattern while migrating code.
  - Converts all files, not just the migrated ones, to those new helpers.

Migrating common.dart and utils.dart should unblock a command-by-command migration to null safety.

Reverts the separate of podspect lints into a step that doesn't do a Flutter upgrade
(flutter/plugins#3700) because without that step we had a
version of Dart too old to run null-safe tooling.

First step of flutter#81912

Author: stuartmorgan-g

.cirrus.yml

@@ -194,6 +194,12 @@ task:
   << : *MACOS_TEMPLATE
   << : *FLUTTER_UPGRADE_TEMPLATE
   matrix:
+    ### iOS+macOS tasks ***
+    - name: lint_darwin_plugins
+      script:
+        # TODO(jmagman): Lint macOS podspecs but skip any that fail library validation.
+        - find . -name "*.podspec" | xargs grep -l "osx" | xargs rm
+        - ./script/tool_runner.sh podspecs
     ### iOS tasks ###
     - name: build_all_plugins_ipa
       env:
@@ -251,14 +257,3 @@ task:
         - ./script/tool_runner.sh build-examples --macos --no-ipa
       drive_script:
         - ./script/tool_runner.sh drive-examples --macos
-
-task:
-  # Don't use FLUTTER_UPGRADE_TEMPLATE, Flutter tooling not needed.
-  << : *MACOS_TEMPLATE
-  << : *TOOL_SETUP_TEMPLATE
-  matrix:
-    - name: lint_darwin_plugins
-      script:
-        # TODO(jmagman): Lint macOS podspecs but skip any that fail library validation.
-        - find . -name "*.podspec" | xargs grep -l "osx" | xargs rm
-        - ./script/tool_runner.sh podspecs

script/tool/bin/flutter_plugin_tools.dart

@@ -2,4 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// @dart=2.9
+
 export 'package:flutter_plugin_tools/src/main.dart';

script/tool/lib/src/analyze_command.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.
 
+// @dart=2.9
+
 import 'dart:async';
 
 import 'package:file/file.dart';
@@ -42,8 +44,8 @@ class AnalyzeCommand extends PluginCommand {
         continue;
       }
 
-      final bool allowed = (argResults[_customAnalysisFlag] as List<String>)
-          .any((String directory) =>
+      final bool allowed = (getStringListArg(_customAnalysisFlag)).any(
+          (String directory) =>
               directory != null &&
               directory.isNotEmpty &&
               p.isWithin(p.join(packagesDir.path, directory), file.path));

script/tool/lib/src/build_examples_command.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.
 
+// @dart=2.9
+
 import 'dart:async';
 import 'dart:io' as io;
 
@@ -52,7 +54,7 @@ class BuildExamplesCommand extends PluginCommand {
     ];
     final Map<String, bool> platforms = <String, bool>{
       for (final String platform in platformSwitches)
-        platform: argResults[platform] as bool
+        platform: getBoolArg(platform)
     };
     if (!platforms.values.any((bool enabled) => enabled)) {
       print(
@@ -63,7 +65,7 @@ class BuildExamplesCommand extends PluginCommand {
     final String flutterCommand =
         const LocalPlatform().isWindows ? 'flutter.bat' : 'flutter';
 
-    final String enableExperiment = argResults[kEnableExperiment] as String;
+    final String enableExperiment = getStringArg(kEnableExperiment);
 
     final List<String> failingPackages = <String>[];
     await for (final Directory plugin in getPlugins()) {

script/tool/lib/src/common.dart

@@ -12,14 +12,13 @@ import 'package:colorize/colorize.dart';
 import 'package:file/file.dart';
 import 'package:git/git.dart';
 import 'package:http/http.dart' as http;
-import 'package:meta/meta.dart';
 import 'package:path/path.dart' as p;
 import 'package:pub_semver/pub_semver.dart';
 import 'package:yaml/yaml.dart';
 
 /// The signature for a print handler for commands that allow overriding the
 /// print destination.
-typedef Print = void Function(Object object);
+typedef Print = void Function(Object? object);
 
 /// Key for windows platform.
 const String kWindows = 'windows';
@@ -50,7 +49,7 @@ const String kEnableExperiment = 'enable-experiment';
 
 /// Returns whether the given directory contains a Flutter package.
 bool isFlutterPackage(FileSystemEntity entity, FileSystem fileSystem) {
-  if (entity == null || entity is! Directory) {
+  if (entity is! Directory) {
     return false;
   }
 
@@ -59,7 +58,7 @@ bool isFlutterPackage(FileSystemEntity entity, FileSystem fileSystem) {
         fileSystem.file(p.join(entity.path, 'pubspec.yaml'));
     final YamlMap pubspecYaml =
         loadYaml(pubspecFile.readAsStringSync()) as YamlMap;
-    final YamlMap dependencies = pubspecYaml['dependencies'] as YamlMap;
+    final YamlMap? dependencies = pubspecYaml['dependencies'] as YamlMap?;
     if (dependencies == null) {
       return false;
     }
@@ -87,7 +86,7 @@ bool pluginSupportsPlatform(
       platform == kMacos ||
       platform == kWindows ||
       platform == kLinux);
-  if (entity == null || entity is! Directory) {
+  if (entity is! Directory) {
     return false;
   }
 
@@ -96,15 +95,15 @@ bool pluginSupportsPlatform(
         fileSystem.file(p.join(entity.path, 'pubspec.yaml'));
     final YamlMap pubspecYaml =
         loadYaml(pubspecFile.readAsStringSync()) as YamlMap;
-    final YamlMap flutterSection = pubspecYaml['flutter'] as YamlMap;
+    final YamlMap? flutterSection = pubspecYaml['flutter'] as YamlMap?;
     if (flutterSection == null) {
       return false;
     }
-    final YamlMap pluginSection = flutterSection['plugin'] as YamlMap;
+    final YamlMap? pluginSection = flutterSection['plugin'] as YamlMap?;
     if (pluginSection == null) {
       return false;
     }
-    final YamlMap platforms = pluginSection['platforms'] as YamlMap;
+    final YamlMap? platforms = pluginSection['platforms'] as YamlMap?;
     if (platforms == null) {
       // Legacy plugin specs are assumed to support iOS and Android.
       if (!pluginSection.containsKey('platforms')) {
@@ -151,7 +150,7 @@ bool isLinuxPlugin(FileSystemEntity entity, FileSystem fileSystem) {
 }
 
 /// Throws a [ToolExit] with `exitCode` and log the `errorMessage` in red.
-void printErrorAndExit({@required String errorMessage, int exitCode = 1}) {
+void printErrorAndExit({required String errorMessage, int exitCode = 1}) {
   final Colorize redError = Colorize(errorMessage)..red();
   print(redError);
   throw ToolExit(exitCode);
@@ -236,30 +235,45 @@ abstract class PluginCommand extends Command<void> {
   /// The git directory to use. By default it uses the parent directory.
   ///
   /// This can be mocked for testing.
-  final GitDir gitDir;
+  final GitDir? gitDir;
 
-  int _shardIndex;
-  int _shardCount;
+  int? _shardIndex;
+  int? _shardCount;
 
   /// The shard of the overall command execution that this instance should run.
   int get shardIndex {
     if (_shardIndex == null) {
       _checkSharding();
     }
-    return _shardIndex;
+    return _shardIndex!;
   }
 
   /// The number of shards this command is divided into.
   int get shardCount {
     if (_shardCount == null) {
       _checkSharding();
     }
-    return _shardCount;
+    return _shardCount!;
+  }
+
+  /// Convenience accessor for boolean arguments.
+  bool getBoolArg(String key) {
+    return (argResults![key] as bool?) ?? false;
+  }
+
+  /// Convenience accessor for String arguments.
+  String getStringArg(String key) {
+    return (argResults![key] as String?) ?? '';
+  }
+
+  /// Convenience accessor for List<String> arguments.
+  List<String> getStringListArg(String key) {
+    return (argResults![key] as List<String>?) ?? <String>[];
   }
 
   void _checkSharding() {
-    final int shardIndex = int.tryParse(argResults[_shardIndexArg] as String);
-    final int shardCount = int.tryParse(argResults[_shardCountArg] as String);
+    final int? shardIndex = int.tryParse(getStringArg(_shardIndexArg));
+    final int? shardCount = int.tryParse(getStringArg(_shardCountArg));
     if (shardIndex == null) {
       usageException('$_shardIndexArg must be an integer');
     }
@@ -317,12 +331,10 @@ abstract class PluginCommand extends Command<void> {
   ///    is a sibling of the packages directory. This is used for a small number
   ///    of packages in the flutter/packages repository.
   Stream<Directory> _getAllPlugins() async* {
-    Set<String> plugins =
-        Set<String>.from(argResults[_pluginsArg] as List<String>);
+    Set<String> plugins = Set<String>.from(getStringListArg(_pluginsArg));
     final Set<String> excludedPlugins =
-        Set<String>.from(argResults[_excludeArg] as List<String>);
-    final bool runOnChangedPackages =
-        argResults[_runOnChangedPackagesArg] as bool;
+        Set<String>.from(getStringListArg(_excludeArg));
+    final bool runOnChangedPackages = getBoolArg(_runOnChangedPackagesArg);
     if (plugins.isEmpty && runOnChangedPackages) {
       plugins = await _getChangedPackages();
     }
@@ -429,9 +441,9 @@ abstract class PluginCommand extends Command<void> {
   /// Throws tool exit if [gitDir] nor root directory is a git directory.
   Future<GitVersionFinder> retrieveVersionFinder() async {
     final String rootDir = packagesDir.parent.absolute.path;
-    final String baseSha = argResults[_kBaseSha] as String;
+    final String baseSha = getStringArg(_kBaseSha);
 
-    GitDir baseGitDir = gitDir;
+    GitDir? baseGitDir = gitDir;
     if (baseGitDir == null) {
       if (!await GitDir.isGitDir(rootDir)) {
         printErrorAndExit(
@@ -490,7 +502,7 @@ class ProcessRunner {
   Future<int> runAndStream(
     String executable,
     List<String> args, {
-    Directory workingDir,
+    Directory? workingDir,
     bool exitOnError = false,
   }) async {
     print(
@@ -522,7 +534,7 @@ class ProcessRunner {
   ///
   /// Returns the [io.ProcessResult] of the [executable].
   Future<io.ProcessResult> run(String executable, List<String> args,
-      {Directory workingDir,
+      {Directory? workingDir,
       bool exitOnError = false,
       bool logOnError = false,
       Encoding stdoutEncoding = io.systemEncoding,
@@ -550,15 +562,15 @@ class ProcessRunner {
   /// passing [workingDir].
   ///
   /// Returns the started [io.Process].
-  Future<io.Process> start(String executable, List<String> args,
-      {Directory workingDirectory}) async {
+  Future<io.Process?> start(String executable, List<String> args,
+      {Directory? workingDirectory}) async {
     final io.Process process = await io.Process.start(executable, args,
         workingDirectory: workingDirectory?.path);
     return process;
   }
 
   String _getErrorString(String executable, List<String> args,
-      {Directory workingDir}) {
+      {Directory? workingDir}) {
     final String workdir = workingDir == null ? '' : ' in ${workingDir.path}';
     return 'ERROR: Unable to execute "$executable ${args.join(' ')}"$workdir.';
   }
@@ -569,7 +581,7 @@ class PubVersionFinder {
   /// Constructor.
   ///
   /// Note: you should manually close the [httpClient] when done using the finder.
-  PubVersionFinder({this.pubHost = defaultPubHost, @required this.httpClient});
+  PubVersionFinder({this.pubHost = defaultPubHost, required this.httpClient});
 
   /// The default pub host to use.
   static const String defaultPubHost = 'https://pub.dev';
@@ -584,8 +596,8 @@ class PubVersionFinder {
 
   /// Get the package version on pub.
   Future<PubVersionFinderResponse> getPackageVersion(
-      {@required String package}) async {
-    assert(package != null && package.isNotEmpty);
+      {required String package}) async {
+    assert(package.isNotEmpty);
     final Uri pubHostUri = Uri.parse(pubHost);
     final Uri url = pubHostUri.replace(path: '/packages/$package.json');
     final http.Response response = await httpClient.get(url);
@@ -618,8 +630,8 @@ class PubVersionFinder {
 class PubVersionFinderResponse {
   /// Constructor.
   PubVersionFinderResponse({this.versions, this.result, this.httpResponse}) {
-    if (versions != null && versions.isNotEmpty) {
-      versions.sort((Version a, Version b) {
+    if (versions != null && versions!.isNotEmpty) {
+      versions!.sort((Version a, Version b) {
         // TODO(cyanglaz): Think about how to handle pre-release version with [Version.prioritize].
         // https://github.com/flutter/flutter/issues/82222
         return b.compareTo(a);
@@ -631,13 +643,13 @@ class PubVersionFinderResponse {
   ///
   /// This is sorted by largest to smallest, so the first element in the list is the largest version.
   /// Might be `null` if the [result] is not [PubVersionFinderResult.success].
-  final List<Version> versions;
+  final List<Version>? versions;
 
   /// The result of the version finder.
-  final PubVersionFinderResult result;
+  final PubVersionFinderResult? result;
 
   /// The response object of the http request.
-  final http.Response httpResponse;
+  final http.Response? httpResponse;
 }
 
 /// An enum representing the result of [PubVersionFinder].
@@ -667,7 +679,7 @@ class GitVersionFinder {
   final GitDir baseGitDir;
 
   /// The base sha used to get diff.
-  final String baseSha;
+  final String? baseSha;
 
   static bool _isPubspec(String file) {
     return file.trim().endsWith('pubspec.yaml');
@@ -684,8 +696,7 @@ class GitVersionFinder {
     final io.ProcessResult changedFilesCommand = await baseGitDir
         .runCommand(<String>['diff', '--name-only', baseSha, 'HEAD']);
     print('Determine diff with base sha: $baseSha');
-    final String changedFilesStdout =
-        changedFilesCommand.stdout.toString() ?? '';
+    final String changedFilesStdout = changedFilesCommand.stdout.toString();
     if (changedFilesStdout.isEmpty) {
       return <String>[];
     }
@@ -696,7 +707,8 @@ class GitVersionFinder {
 
   /// Get the package version specified in the pubspec file in `pubspecPath` and
   /// at the revision of `gitRef` (defaulting to the base if not provided).
-  Future<Version> getPackageVersion(String pubspecPath, {String gitRef}) async {
+  Future<Version?> getPackageVersion(String pubspecPath,
+      {String? gitRef}) async {
     final String ref = gitRef ?? (await _getBaseSha());
 
     io.ProcessResult gitShow;
@@ -707,20 +719,19 @@ class GitVersionFinder {
       return null;
     }
     final String fileContent = gitShow.stdout as String;
-    final String versionString = loadYaml(fileContent)['version'] as String;
+    final String? versionString = loadYaml(fileContent)['version'] as String?;
     return versionString == null ? null : Version.parse(versionString);
   }
 
   Future<String> _getBaseSha() async {
-    if (baseSha != null && baseSha.isNotEmpty) {
-      return baseSha;
+    if (baseSha != null && baseSha!.isNotEmpty) {
+      return baseSha!;
     }
 
     io.ProcessResult baseShaFromMergeBase = await baseGitDir.runCommand(
         <String>['merge-base', '--fork-point', 'FETCH_HEAD', 'HEAD'],
         throwOnError: false);
-    if (baseShaFromMergeBase == null ||
-        baseShaFromMergeBase.stderr != null ||
+    if (baseShaFromMergeBase.stderr != null ||
         baseShaFromMergeBase.stdout == null) {
       baseShaFromMergeBase = await baseGitDir
           .runCommand(<String>['merge-base', 'FETCH_HEAD', 'HEAD']);

script/tool/lib/src/create_all_plugins_app_command.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.
 
+// @dart=2.9
+
 import 'dart:async';
 import 'dart:io' as io;