feat(dart_frog_cli): improve hot reload error reporting/recovery

Author: felangel

packages/dart_frog_cli/lib/src/commands/dev/dev.dart

@@ -1,11 +1,14 @@
 import 'dart:convert';
 import 'dart:io' as io;
 
+import 'package:collection/collection.dart';
 import 'package:dart_frog_cli/src/command.dart';
 import 'package:dart_frog_cli/src/commands/commands.dart';
 import 'package:dart_frog_cli/src/commands/dev/templates/dart_frog_dev_server_bundle.dart';
 import 'package:mason/mason.dart';
+import 'package:meta/meta.dart';
 import 'package:path/path.dart' as path;
+import 'package:stream_transform/stream_transform.dart';
 import 'package:watcher/watcher.dart';
 
 /// Typedef for [io.Process.start].
@@ -85,6 +88,7 @@ class DevCommand extends DartFrogCommand {
 
   @override
   Future<int> run() async {
+    var reloading = false;
     var hotReloadEnabled = false;
     final port = io.Platform.environment['PORT'] ?? results['port'] as String;
     final generator = await _generator(dartFrogDevServerBundle);
@@ -104,6 +108,12 @@ class DevCommand extends DartFrogCommand {
       );
     }
 
+    Future<void> reload() async {
+      reloading = true;
+      await codegen();
+      reloading = false;
+    }
+
     Future<void> serve() async {
       final process = await _startProcess(
         'dart',
@@ -119,7 +129,12 @@ class DevCommand extends DartFrogCommand {
       var hasError = false;
       process.stderr.listen((_) async {
         hasError = true;
-        logger.err(utf8.decode(_));
+        if (reloading) return;
+
+        final message = utf8.decode(_).trim();
+        if (message.isEmpty) return;
+
+        logger.err(message);
 
         if (!hotReloadEnabled) {
           await _killProcess(process);
@@ -132,8 +147,10 @@ class DevCommand extends DartFrogCommand {
       process.stdout.listen((_) {
         final message = utf8.decode(_).trim();
         if (message.contains('[hotreload]')) hotReloadEnabled = true;
-        if (!hasError) _generatorTarget.cacheLatestSnapshot();
         if (message.isNotEmpty) logger.info(message);
+        final shouldCacheSnapshot =
+            hotReloadEnabled && !hasError && message.isNotEmpty;
+        if (shouldCacheSnapshot) _generatorTarget.cacheLatestSnapshot();
         hasError = false;
       });
     }
@@ -146,14 +163,16 @@ class DevCommand extends DartFrogCommand {
     final public = path.join(cwd.path, 'public');
     final routes = path.join(cwd.path, 'routes');
 
-    bool shouldRunCodegen(WatchEvent event) {
+    bool shouldReload(WatchEvent event) {
       return path.isWithin(routes, event.path) ||
           path.isWithin(public, event.path);
     }
 
     final watcher = _directoryWatcher(path.join(cwd.path));
-    final subscription =
-        watcher.events.where(shouldRunCodegen).listen((_) => codegen());
+    final subscription = watcher.events
+        .where(shouldReload)
+        .debounce(Duration.zero)
+        .listen((_) => reload());
 
     await subscription.asFuture<void>();
     await subscription.cancel();
@@ -175,6 +194,7 @@ class DevCommand extends DartFrogCommand {
 /// {@template cached_file}
 /// A cached file which consists of the file path and contents.
 /// {@endtemplate}
+@immutable
 class CachedFile {
   /// {@macro cached_file}
   const CachedFile({required this.path, required this.contents});
@@ -184,6 +204,19 @@ class CachedFile {
 
   /// The contents of the generated file.s
   final List<int> contents;
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) return true;
+    final listEquals = const DeepCollectionEquality().equals;
+
+    return other is CachedFile &&
+        other.path == path &&
+        listEquals(other.contents, contents);
+  }
+
+  @override
+  int get hashCode => Object.hashAll([contents, path]);
 }
 
 /// Signature for the `createFile` method on [DirectoryGeneratorTarget].
@@ -217,7 +250,7 @@ class RestorableDirectoryGeneratorTarget extends DirectoryGeneratorTarget {
   /// Cache the latest recorded snapshot.
   void cacheLatestSnapshot() {
     final snapshot = _latestSnapshot;
-    if (snapshot == null) return;
+    if (snapshot == null || _cachedSnapshot == snapshot) return;
     _cachedSnapshot = snapshot;
   }
 

packages/dart_frog_cli/lib/src/commands/dev/templates/dart_frog_dev_server_bundle.dart

@@ -14,6 +14,7 @@ dependencies:
   mason: ^0.1.0-dev.31
   meta: ^1.7.0
   path: ^1.8.1
+  stream_transform: ^2.0.0
   watcher: ^1.0.1
 
 dev_dependencies:

packages/dart_frog_cli/pubspec.yaml

@@ -177,8 +177,9 @@ void main() {
       ]);
     });
 
-    test('runs codegen when changes are made to the public/routes directory',
-        () async {
+    test(
+        'runs codegen w/debounce '
+        'when changes are made to the public/routes directory', () async {
       final controller = StreamController<WatchEvent>();
       final generatorHooks = _MockGeneratorHooks();
       when(
@@ -219,14 +220,22 @@ void main() {
         ),
       ).called(1);
 
-      controller.add(
-        WatchEvent(
-          ChangeType.MODIFY,
-          path.join(Directory.current.path, 'routes', 'index.dart'),
-        ),
-      );
+      controller
+        ..add(
+          WatchEvent(
+            ChangeType.ADD,
+            path.join(Directory.current.path, 'routes', 'users.dart'),
+          ),
+        )
+        ..add(
+          WatchEvent(
+            ChangeType.REMOVE,
+            path.join(Directory.current.path, 'routes', 'user.dart'),
+          ),
+        );
 
       await Future<void>.delayed(Duration.zero);
+      await Future<void>.delayed(Duration.zero);
 
       verify(
         () => generator.generate(
@@ -243,6 +252,7 @@ void main() {
         ),
       );
 
+      await Future<void>.delayed(Duration.zero);
       await Future<void>.delayed(Duration.zero);
 
       verify(
@@ -260,6 +270,7 @@ void main() {
         ),
       );
 
+      await Future<void>.delayed(Duration.zero);
       await Future<void>.delayed(Duration.zero);
 
       verifyNever(
@@ -354,6 +365,56 @@ void main() {
       verify(() => logger.err(error)).called(1);
     });
 
+    test('ignores file not found errors due to file renames', () async {
+      final generatorHooks = _MockGeneratorHooks();
+      final stdoutController = StreamController<List<int>>();
+      final stderrController = StreamController<List<int>>();
+      when(
+        () => generatorHooks.preGen(
+          vars: any(named: 'vars'),
+          workingDirectory: any(named: 'workingDirectory'),
+          onVarsChanged: any(named: 'onVarsChanged'),
+        ),
+      ).thenAnswer((invocation) async {
+        (invocation.namedArguments[const Symbol('onVarsChanged')] as Function(
+          Map<String, dynamic> vars,
+        ))
+            .call(<String, dynamic>{});
+      });
+      when(
+        () => generator.generate(
+          any(),
+          vars: any(named: 'vars'),
+          fileConflictResolution: FileConflictResolution.overwrite,
+        ),
+      ).thenAnswer((_) async => []);
+      when(() => generator.hooks).thenReturn(generatorHooks);
+      when(() => generatorTarget.restore()).thenAnswer((_) async {});
+      when(() => process.stdout).thenAnswer((_) => stdoutController.stream);
+      when(() => process.stderr).thenAnswer((_) => stderrController.stream);
+      when(() => directoryWatcher.events).thenAnswer(
+        (_) => const Stream.empty(),
+      );
+
+      command.run().ignore();
+
+      stdoutController.add(utf8.encode('[hotreload] hot reload enabled'));
+      await untilCalled(() => generatorTarget.cacheLatestSnapshot());
+      verify(() => generatorTarget.cacheLatestSnapshot()).called(1);
+
+      const error =
+          "./dart_frog/server.dart:7:8: Error: Error when reading 'routes/example.dart': The system cannot find the file specified.";
+
+      stderrController.add(utf8.encode(error));
+
+      await stderrController.close();
+      await stdoutController.close();
+
+      verifyNever(() => generatorTarget.cacheLatestSnapshot());
+      verifyNever(() => generatorTarget.restore());
+      verifyNever(() => logger.err(error));
+    });
+
     test('port can be specified using --port', () async {
       when<dynamic>(() => argResults['port']).thenReturn('4242');
       final generatorHooks = _MockGeneratorHooks();