fix: run search bar commands on Enter and filter by /folder

test/note_list_harness.dart

@@ -0,0 +1,56 @@
+import 'dart:io';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:muzzle_velocity/note_list.dart';
+import 'package:path_provider_platform_interface/path_provider_platform_interface.dart';
+import 'package:plugin_platform_interface/plugin_platform_interface.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+class _FakePathProvider extends PathProviderPlatform
+    with MockPlatformInterfaceMixin {
+  _FakePathProvider(this.path);
+  final String path;
+
+  @override
+  Future<String?> getApplicationDocumentsPath() async => path;
+}
+
+/// Creates a temporary notes folder with [files] (relative path to content)
+/// and makes it the app's default notes directory.
+Directory setUpNotes(Map<String, String> files) {
+  final notes = Directory.systemTemp.createTempSync('mv-list');
+  files.forEach((name, content) {
+    File('${notes.path}/$name')
+      ..createSync(recursive: true)
+      ..writeAsStringSync(content);
+  });
+  PathProviderPlatform.instance = _FakePathProvider(notes.path);
+  SharedPreferences.setMockInitialValues({'initialized': true});
+  return notes;
+}
+
+/// Pumps the note list, letting its real file I/O finish.
+Future<void> pumpList(
+  WidgetTester tester, {
+  void Function(bool)? toggleTheme,
+  VoidCallback? toggleTags,
+}) async {
+  await tester.runAsync(() async {
+    await tester.pumpWidget(MaterialApp(
+      home: NoteListScreen(
+        toggleTheme: toggleTheme ?? (_) {},
+        toggleTags: toggleTags ?? () {},
+        isDarkMode: false,
+        showTags: true,
+      ),
+    ));
+    await Future<void>.delayed(const Duration(milliseconds: 200));
+  });
+  await tester.pumpAndSettle();
+}
+
+/// Titles of the notes currently listed.
+List<String> listedNotes(WidgetTester tester) => [
+      for (final tile in tester.widgetList<ListTile>(find.byType(ListTile)))
+        (tile.title as Text).data!,
+    ];