feat(shorebird_cli): verify flutter engine revision (#96)

packages/shorebird_cli/lib/src/command_runner.dart

@@ -1,15 +1,24 @@
+import 'dart:io';
+
 import 'package:args/args.dart';
 import 'package:args/command_runner.dart';
 import 'package:cli_completion/cli_completion.dart';
 import 'package:mason_logger/mason_logger.dart';
 import 'package:pub_updater/pub_updater.dart';
 import 'package:shorebird_cli/src/commands/commands.dart';
+import 'package:shorebird_cli/src/flutter_engine_revision.dart';
 import 'package:shorebird_cli/src/version.dart';
 
 const executableName = 'shorebird';
 const packageName = 'shorebird_cli';
 const description = 'The shorebird command-line tool';
 
+typedef RunProcess = Future<ProcessResult> Function(
+  String executable,
+  List<String> arguments, {
+  bool runInShell,
+});
+
 /// {@template shorebird_cli_command_runner}
 /// A [CommandRunner] for the CLI.
 ///
@@ -19,9 +28,13 @@ const description = 'The shorebird command-line tool';
 /// {@endtemplate}
 class ShorebirdCliCommandRunner extends CompletionCommandRunner<int> {
   /// {@macro shorebird_cli_command_runner}
-  ShorebirdCliCommandRunner({PubUpdater? pubUpdater, Logger? logger})
-      : _logger = logger ?? Logger(),
+  ShorebirdCliCommandRunner({
+    PubUpdater? pubUpdater,
+    Logger? logger,
+    RunProcess? runProcess,
+  })  : _logger = logger ?? Logger(),
         _pubUpdater = pubUpdater ?? PubUpdater(),
+        _runProcess = runProcess ?? Process.run,
         super(executableName, description) {
     argParser
       ..addFlag(
@@ -50,6 +63,7 @@ class ShorebirdCliCommandRunner extends CompletionCommandRunner<int> {
 
   final Logger _logger;
   final PubUpdater _pubUpdater;
+  final RunProcess _runProcess;
 
   @override
   Future<int> run(Iterable<String> args) async {
@@ -58,6 +72,30 @@ class ShorebirdCliCommandRunner extends CompletionCommandRunner<int> {
       if (topLevelResults['verbose'] == true) {
         _logger.level = Level.verbose;
       }
+
+      try {
+        final flutterEngineRevision = await _getFlutterEngineRevision();
+        if (flutterEngineRevision != requiredFlutterEngineRevision) {
+          _logger.err(
+            '''
+Shorebird only works with the latest stable channel at this time.
+
+To use the latest stable channel, run:
+  flutter channel stable
+  flutter upgrade
+
+If you believe you're already on the latest stable channel, please ask on Discord, we're happy to help!
+
+Required engine revision: "$requiredFlutterEngineRevision"
+Detected engine revision: "$flutterEngineRevision"''',
+          );
+          return ExitCode.software.code;
+        }
+      } catch (error) {
+        _logger.err('Failed to get Flutter engine revision.\n$error');
+        return ExitCode.software.code;
+      }
+
       return await runCommand(topLevelResults) ?? ExitCode.success.code;
     } on FormatException catch (e, stackTrace) {
       // On format errors, show the commands error message, root usage and
@@ -104,6 +142,23 @@ class ShorebirdCliCommandRunner extends CompletionCommandRunner<int> {
     return exitCode;
   }
 
+  Future<String> _getFlutterEngineRevision() async {
+    final result = await _runProcess(
+      'flutter',
+      ['--version'],
+      runInShell: true,
+    );
+    if (result.exitCode != 0) throw Exception('${result.stderr}');
+
+    final output = result.stdout as String;
+    final regexp = RegExp(r'Engine • revision (.*?$)', multiLine: true);
+    final flutterEngineRevision = regexp.firstMatch(output)?.group(1);
+    if (flutterEngineRevision == null) {
+      throw Exception('Unable to determine the Flutter engine revision.');
+    }
+    return flutterEngineRevision;
+  }
+
   /// Checks if the current version (set by the build runner on the
   /// version.dart file) is the most recent one. If not, show a prompt to the
   /// user.

packages/shorebird_cli/lib/src/flutter_engine_revision.dart

@@ -0,0 +1,3 @@
+/// The hash of the Flutter engine required by Shorebird.
+/// Currently, Shorebird only supports the latest stable Flutter channel.
+const requiredFlutterEngineRevision = '1837b5be5f';

packages/shorebird_cli/test/src/command_runner_test.dart

@@ -41,13 +41,82 @@ void main() {
 
       processResult = _MockProcessResult();
       when(() => processResult.exitCode).thenReturn(ExitCode.success.code);
+      when(() => processResult.stdout).thenReturn(
+        '''
+Flutter 3.7.7 • channel stable • git@github.com:flutter/flutter.git
+Framework • revision 2ad6cd72c0 (12 days ago) • 2023-03-08 09:41:59 -0800
+Engine • revision 1837b5be5f
+Tools • Dart 2.19.4 • DevTools 2.20.1
+''',
+      );
 
       commandRunner = ShorebirdCliCommandRunner(
         logger: logger,
         pubUpdater: pubUpdater,
+        runProcess: (
+          String executable,
+          List<String> arguments, {
+          bool runInShell = false,
+        }) async {
+          return processResult;
+        },
       );
     });
 
+    test('exits when Flutter is not installed', () async {
+      const error = 'oops something went wrong';
+      when(() => processResult.exitCode).thenReturn(1);
+      when(() => processResult.stderr).thenReturn(error);
+
+      final result = await commandRunner.run(['--version']);
+      expect(result, equals(ExitCode.software.code));
+      verify(() => logger.err(any(that: contains(error)))).called(1);
+    });
+
+    test('exits when unable to detect the Flutter engine revision', () async {
+      when(() => processResult.exitCode).thenReturn(0);
+      when(() => processResult.stdout).thenReturn(
+        '''
+Flutter 3.7.7 • channel stable •
+Framework • revision 2ad6cd72c0 (12 days ago) • 2023-03-08 09:41:59 -0800
+Tools • Dart 2.19.4 • DevTools 2.20.1
+''',
+      );
+
+      final result = await commandRunner.run(['--version']);
+      expect(result, equals(ExitCode.software.code));
+      verify(
+        () => logger.err(
+          any(
+            that: contains('Unable to determine the Flutter engine revision.'),
+          ),
+        ),
+      ).called(1);
+    });
+
+    test('exits when there is an incompatible Flutter engine', () async {
+      when(() => processResult.stdout).thenReturn(
+        '''
+Flutter 3.7.7 • channel stable •
+Framework • revision 2ad6cd72c0 (12 days ago) • 2023-03-08 09:41:59 -0800
+Engine • revision 639e313f99
+Tools • Dart 2.19.4 • DevTools 2.20.1
+''',
+      );
+
+      final result = await commandRunner.run(['--version']);
+      expect(result, equals(ExitCode.software.code));
+      verify(
+        () => logger.err(
+          any(
+            that: contains(
+              '''Shorebird only works with the latest stable channel at this time.''',
+            ),
+          ),
+        ),
+      ).called(1);
+    });
+
     test('shows update message when newer version exists', () async {
       when(
         () => pubUpdater.getLatestVersion(any()),