[flutter_tools] Precache after channel switch (#118129)

Fixes https://github.com/flutter/flutter/issues/44118

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

@@ -9,6 +9,8 @@ import '../runner/flutter_command.dart';
 import '../runner/flutter_command_runner.dart';
 import '../version.dart';
 
+import 'upgrade.dart' show precacheArtifacts;
+
 class ChannelCommand extends FlutterCommand {
   ChannelCommand({ bool verboseHelp = false }) {
     argParser.addFlag(
@@ -17,6 +19,12 @@ class ChannelCommand extends FlutterCommand {
       help: 'Include all the available branches (including local branches) when listing channels.',
       hide: !verboseHelp,
     );
+    argParser.addFlag(
+      'cache-artifacts',
+      help: 'After switching channels, download all required binary artifacts. '
+            'This is the equivalent of running "flutter precache" with the "--all-platforms" flag.',
+      defaultsTo: true,
+    );
   }
 
   @override
@@ -134,6 +142,9 @@ class ChannelCommand extends FlutterCommand {
       globals.printStatus('This is not an official channel. For a list of available channels, try "flutter channel".');
     }
     await _checkout(branchName);
+    if (boolArg('cache-artifacts')) {
+      await precacheArtifacts(Cache.flutterRoot);
+    }
     globals.printStatus("Successfully switched to flutter channel '$branchName'.");
     globals.printStatus("To ensure that you're on the latest build from this channel, run 'flutter upgrade'");
   }

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

@@ -22,8 +22,11 @@ class PrecacheCommand extends FlutterCommand {
        _platform = platform,
        _logger = logger,
        _featureFlags = featureFlags {
-    argParser.addFlag('all-platforms', abbr: 'a', negatable: false,
-        help: 'Precache artifacts for all host platforms.');
+    argParser.addFlag('all-platforms',
+        abbr: 'a',
+        negatable: false,
+        help: 'Precache artifacts for all host platforms.',
+        aliases: const <String>['all']);
     argParser.addFlag('force', abbr: 'f', negatable: false,
         help: 'Force re-downloading of artifacts.');
     argParser.addFlag('android',

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

@@ -88,7 +88,6 @@ class UpgradeCommand extends FlutterCommand {
 
 @visibleForTesting
 class UpgradeCommandRunner {
-
   String? workingDirectory; // set in runCommand() above
 
   Future<FlutterCommandResult> runCommand({
@@ -205,7 +204,7 @@ class UpgradeCommandRunner {
     // Make sure the welcome message re-display is delayed until the end.
     final PersistentToolState persistentToolState = globals.persistentToolState!;
     persistentToolState.setShouldRedisplayWelcomeMessage(false);
-    await precacheArtifacts();
+    await precacheArtifacts(workingDirectory);
     await updatePackages(flutterVersion);
     await runDoctor();
     // Force the welcome message to re-display following the upgrade.
@@ -318,27 +317,6 @@ class UpgradeCommandRunner {
     }
   }
 
-  /// Update the engine repository and precache all artifacts.
-  ///
-  /// Check for and download any engine and pkg/ updates. We run the 'flutter'
-  /// shell script reentrantly here so that it will download the updated
-  /// Dart and so forth if necessary.
-  Future<void> precacheArtifacts() async {
-    globals.printStatus('');
-    globals.printStatus('Upgrading engine...');
-    final int code = await globals.processUtils.stream(
-      <String>[
-        globals.fs.path.join('bin', 'flutter'), '--no-color', '--no-version-check', 'precache',
-      ],
-      workingDirectory: workingDirectory,
-      allowReentrantFlutter: true,
-      environment: Map<String, String>.of(globals.platform.environment),
-    );
-    if (code != 0) {
-      throwToolExit(null, exitCode: code);
-    }
-  }
-
   /// Update the user's packages.
   Future<void> updatePackages(FlutterVersion flutterVersion) async {
     globals.printStatus('');
@@ -367,3 +345,24 @@ class UpgradeCommandRunner {
     );
   }
 }
+
+/// Update the engine repository and precache all artifacts.
+///
+/// Check for and download any engine and pkg/ updates. We run the 'flutter'
+/// shell script reentrantly here so that it will download the updated
+/// Dart and so forth if necessary.
+Future<void> precacheArtifacts([String? workingDirectory]) async {
+  globals.printStatus('');
+  globals.printStatus('Upgrading engine...');
+  final int code = await globals.processUtils.stream(
+    <String>[
+      globals.fs.path.join('bin', 'flutter'), '--no-color', '--no-version-check', 'precache',
+    ],
+    allowReentrantFlutter: true,
+    environment: Map<String, String>.of(globals.platform.environment),
+    workingDirectory: workingDirectory,
+  );
+  if (code != 0) {
+    throwToolExit(null, exitCode: code);
+  }
+}

packages/flutter_tools/test/commands.shard/permeable/upgrade_test.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:file/memory.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/io.dart';
 import 'package:flutter_tools/src/base/platform.dart';
@@ -327,7 +328,7 @@ void main() {
           environment: <String, String>{'FLUTTER_ALREADY_LOCKED': 'true', ...fakePlatform.environment}
         ),
       );
-      await realCommandRunner.precacheArtifacts();
+      await precacheArtifacts();
       expect(processManager, hasNoRemainingExpectations);
     }, overrides: <Type, Generator>{
       ProcessManager: () => processManager,
@@ -408,6 +409,7 @@ void main() {
         late FakeProcessManager fakeProcessManager;
         late Directory tempDir;
         late File flutterToolState;
+        late FileSystem fs;
 
         setUp(() {
           Cache.disableLocking();
@@ -424,7 +426,8 @@ void main() {
               stdout: 'v1.12.16-19-gb45b676af',
             ),
           ]);
-          tempDir = globals.fs.systemTempDirectory.createTempSync('flutter_upgrade_test.');
+          fs = MemoryFileSystem.test();
+          tempDir = fs.systemTempDirectory.createTempSync('flutter_upgrade_test.');
           flutterToolState = tempDir.childFile('.flutter_tool_state');
         });
 
@@ -434,6 +437,7 @@ void main() {
         });
 
         testUsingContext('upgrade continue prints welcome message', () async {
+          fakeProcessManager = FakeProcessManager.any();
           final UpgradeCommand upgradeCommand = UpgradeCommand(
             verboseHelp: false,
             commandRunner: fakeCommandRunner,
@@ -451,6 +455,7 @@ void main() {
             containsPair('redisplay-welcome-message', true),
           );
         }, overrides: <Type, Generator>{
+          FileSystem: () => fs,
           FlutterVersion: () => FakeFlutterVersion(),
           ProcessManager: () => fakeProcessManager,
           PersistentToolState: () => PersistentToolState.test(
@@ -479,9 +484,6 @@ class FakeUpgradeCommandRunner extends UpgradeCommandRunner {
   @override
   Future<void> attemptReset(String newRevision) async {}
 
-  @override
-  Future<void> precacheArtifacts() async {}
-
   @override
   Future<void> updatePackages(FlutterVersion flutterVersion) async {}
 

packages/flutter_tools/test/general.shard/args_test.dart

@@ -5,6 +5,7 @@
 import 'package:args/args.dart';
 import 'package:args/command_runner.dart';
 import 'package:flutter_tools/executable.dart' as executable;
+import 'package:flutter_tools/src/cache.dart';
 import 'package:flutter_tools/src/commands/analyze.dart';
 import 'package:flutter_tools/src/runner/flutter_command.dart';
 import 'package:flutter_tools/src/runner/flutter_command_runner.dart';
@@ -15,6 +16,14 @@ import '../src/testbed.dart';
 import 'runner/utils.dart';
 
 void main() {
+  setUpAll(() {
+    Cache.disableLocking();
+  });
+
+  tearDownAll(() {
+    Cache.enableLocking();
+  });
+
   test('Help for command line arguments is consistently styled and complete', () => Testbed().run(() {
     final FlutterCommandRunner runner = FlutterCommandRunner(verboseHelp: true);
     executable.generateCommands(

packages/flutter_tools/test/general.shard/channel_test.dart

@@ -242,15 +242,18 @@ void main() {
     });
 
     testUsingContext('can switch channels', () async {
-      fakeProcessManager.addCommands(<FakeCommand>[
-        const FakeCommand(
+      fakeProcessManager.addCommands(const <FakeCommand>[
+        FakeCommand(
           command: <String>['git', 'fetch'],
         ),
-        const FakeCommand(
+        FakeCommand(
           command: <String>['git', 'show-ref', '--verify', '--quiet', 'refs/heads/beta'],
         ),
-        const FakeCommand(
-            command: <String>['git', 'checkout', 'beta', '--']
+        FakeCommand(
+          command: <String>['git', 'checkout', 'beta', '--']
+        ),
+        FakeCommand(
+          command: <String>['bin/flutter', '--no-color', '--no-version-check', 'precache'],
         ),
       ]);
 
@@ -265,16 +268,19 @@ void main() {
       );
       expect(testLogger.errorText, hasLength(0));
 
-      fakeProcessManager.addCommands(<FakeCommand>[
-        const FakeCommand(
+      fakeProcessManager.addCommands(const <FakeCommand>[
+        FakeCommand(
           command: <String>['git', 'fetch'],
         ),
-        const FakeCommand(
+        FakeCommand(
           command: <String>['git', 'show-ref', '--verify', '--quiet', 'refs/heads/stable'],
         ),
-        const FakeCommand(
+        FakeCommand(
             command: <String>['git', 'checkout', 'stable', '--']
         ),
+        FakeCommand(
+          command: <String>['bin/flutter', '--no-color', '--no-version-check', 'precache'],
+        ),
       ]);
 
       await runner.run(<String>['channel', 'stable']);
@@ -286,16 +292,19 @@ void main() {
     });
 
     testUsingContext('switching channels prompts to run flutter upgrade', () async {
-      fakeProcessManager.addCommands(<FakeCommand>[
-        const FakeCommand(
+      fakeProcessManager.addCommands(const <FakeCommand>[
+        FakeCommand(
           command: <String>['git', 'fetch'],
         ),
-        const FakeCommand(
+        FakeCommand(
           command: <String>['git', 'show-ref', '--verify', '--quiet', 'refs/heads/beta'],
         ),
-        const FakeCommand(
+        FakeCommand(
             command: <String>['git', 'checkout', 'beta', '--']
         ),
+        FakeCommand(
+          command: <String>['bin/flutter', '--no-color', '--no-version-check', 'precache'],
+        ),
       ]);
 
       final ChannelCommand command = ChannelCommand();
@@ -322,16 +331,19 @@ void main() {
     // This verifies that bug https://github.com/flutter/flutter/issues/21134
     // doesn't return.
     testUsingContext('removes version stamp file when switching channels', () async {
-      fakeProcessManager.addCommands(<FakeCommand>[
-        const FakeCommand(
+      fakeProcessManager.addCommands(const <FakeCommand>[
+        FakeCommand(
           command: <String>['git', 'fetch'],
         ),
-        const FakeCommand(
+        FakeCommand(
           command: <String>['git', 'show-ref', '--verify', '--quiet', 'refs/heads/beta'],
         ),
-        const FakeCommand(
+        FakeCommand(
           command: <String>['git', 'checkout', 'beta', '--']
         ),
+        FakeCommand(
+          command: <String>['bin/flutter', '--no-color', '--no-version-check', 'precache'],
+        ),
       ]);
 
       final File versionCheckFile = globals.cache.getStampFileFor(