feat(mobile): custom date range for map (#26205)

* feat(mobile): custom date range for map

* refactor: rename timerange & remove isvalid

* refactor: rename customtimerange variables

* refactor: add back setRelativeTime

* refactor: implement suggestions

* refactor: suggestions

* fix: ifPresent

* fix: context.locale

* chore: restrict selection

* refactor: move options to mapconfig

* refactor: move model to domain

* chore: locale toLanguageTag

* add map codec tests

* rebase

---------

Co-authored-by: shenlong-tanwen <139912620+shalong-tanwen@users.noreply.github.com>

i18n/en.json

@@ -1524,6 +1524,7 @@
   "not_available": "N/A",
   "not_in_any_album": "Not in any album",
   "not_selected": "Not selected",
+  "not_set": "Not set",
   "notes": "Notes",
   "nothing_here_yet": "Nothing here yet",
   "notification_backup_reliability": "Enable notifications to improve background backup reliability",

mobile/lib/domain/models/config/app_config.dart

@@ -153,6 +153,8 @@ class AppConfig {
             .timelineStorageIndicator => timeline.storageIndicator,
             .mapShowFavoriteOnly => map.favoritesOnly,
             .mapRelativeDate => map.relativeDays,
+            .mapCustomFrom => map.customFrom,
+            .mapCustomTo => map.customTo,
             .mapIncludeArchived => map.includeArchived,
             .mapThemeMode => map.themeMode,
             .mapWithPartners => map.withPartners,
@@ -207,6 +209,8 @@ class AppConfig {
       .timelineStorageIndicator => copyWith(timeline: timeline.copyWith(storageIndicator: value as bool)),
       .mapShowFavoriteOnly => copyWith(map: map.copyWith(favoritesOnly: value as bool)),
       .mapRelativeDate => copyWith(map: map.copyWith(relativeDays: value as int)),
+      .mapCustomFrom => copyWith(map: map.copyWith(customFrom: .fromNullable(value as DateTime?))),
+      .mapCustomTo => copyWith(map: map.copyWith(customTo: .fromNullable(value as DateTime?))),
       .mapIncludeArchived => copyWith(map: map.copyWith(includeArchived: value as bool)),
       .mapThemeMode => copyWith(map: map.copyWith(themeMode: value as ThemeMode)),
       .mapWithPartners => copyWith(map: map.copyWith(withPartners: value as bool)),

mobile/lib/domain/models/config/map_config.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:immich_mobile/utils/option.dart';
 
 class MapConfig {
   final int relativeDays;
@@ -6,13 +7,17 @@ class MapConfig {
   final bool includeArchived;
   final ThemeMode themeMode;
   final bool withPartners;
+  final DateTime? customFrom;
+  final DateTime? customTo;
 
   const MapConfig({
     this.relativeDays = 0,
     this.favoritesOnly = false,
     this.includeArchived = false,
-    this.themeMode = ThemeMode.system,
+    this.themeMode = .system,
     this.withPartners = false,
+    this.customFrom,
+    this.customTo,
   });
 
   MapConfig copyWith({
@@ -21,12 +26,16 @@ class MapConfig {
     bool? includeArchived,
     ThemeMode? themeMode,
     bool? withPartners,
+    Option<DateTime>? customFrom,
+    Option<DateTime>? customTo,
   }) => MapConfig(
     relativeDays: relativeDays ?? this.relativeDays,
     favoritesOnly: favoritesOnly ?? this.favoritesOnly,
     includeArchived: includeArchived ?? this.includeArchived,
     themeMode: themeMode ?? this.themeMode,
     withPartners: withPartners ?? this.withPartners,
+    customFrom: customFrom.patch(this.customFrom),
+    customTo: customTo.patch(this.customTo),
   );
 
   @override
@@ -37,12 +46,15 @@ class MapConfig {
           other.favoritesOnly == favoritesOnly &&
           other.includeArchived == includeArchived &&
           other.themeMode == themeMode &&
-          other.withPartners == withPartners);
+          other.withPartners == withPartners &&
+          other.customFrom == customFrom &&
+          other.customTo == customTo);
 
   @override
-  int get hashCode => Object.hash(relativeDays, favoritesOnly, includeArchived, themeMode, withPartners);
+  int get hashCode =>
+      Object.hash(relativeDays, favoritesOnly, includeArchived, themeMode, withPartners, customFrom, customTo);
 
   @override
   String toString() =>
-      'MapConfig(relativeDays: $relativeDays, favoritesOnly: $favoritesOnly, includeArchived: $includeArchived, themeMode: $themeMode, withPartners: $withPartners)';
+      'MapConfig(relativeDays: $relativeDays, favoritesOnly: $favoritesOnly, includeArchived: $includeArchived, themeMode: $themeMode, withPartners: $withPartners, customFrom: $customFrom, customTo: $customTo)';
 }

mobile/lib/domain/models/settings_key.dart

@@ -55,6 +55,8 @@ enum SettingsKey<T> {
   // Map
   mapShowFavoriteOnly<bool>(),
   mapRelativeDate<int>(),
+  mapCustomFrom<DateTime?>(),
+  mapCustomTo<DateTime?>(),
   mapIncludeArchived<bool>(),
   mapThemeMode<ThemeMode>(codec: EnumCodec(ThemeMode.values)),
   mapWithPartners<bool>(),

mobile/lib/domain/models/time_range.model.dart

@@ -0,0 +1,15 @@
+import 'package:immich_mobile/utils/option.dart';
+
+class TimeRange {
+  final DateTime? from;
+  final DateTime? to;
+
+  const TimeRange({this.from, this.to});
+
+  TimeRange copyWith({Option<DateTime>? from, Option<DateTime>? to}) {
+    return TimeRange(from: from.patch(this.from), to: to.patch(this.to));
+  }
+
+  TimeRange clearFrom() => TimeRange(to: to);
+  TimeRange clearTo() => TimeRange(from: from);
+}

mobile/lib/infrastructure/repositories/map.repository.dart

@@ -27,7 +27,18 @@ class DriftMapRepository extends DriftDatabaseRepository {
         condition = condition & _db.remoteAssetEntity.isFavorite.equals(true);
       }
 
-      if (options.relativeDays != 0) {
+      final timeRange = options.timeRange;
+      final hasCustomRange = timeRange.from != null || timeRange.to != null;
+
+      if (hasCustomRange) {
+        if (timeRange.from != null) {
+          condition = condition & _db.remoteAssetEntity.createdAt.isBiggerOrEqualValue(timeRange.from!);
+        }
+
+        if (timeRange.to != null) {
+          condition = condition & _db.remoteAssetEntity.createdAt.isSmallerOrEqualValue(timeRange.to!);
+        }
+      } else if (options.relativeDays > 0) {
         final cutoffDate = DateTime.now().toUtc().subtract(Duration(days: options.relativeDays));
         condition = condition & _db.remoteAssetEntity.createdAt.isBiggerOrEqualValue(cutoffDate);
       }

mobile/lib/infrastructure/repositories/timeline.repository.dart

@@ -4,6 +4,7 @@ import 'package:drift/drift.dart';
 import 'package:easy_localization/easy_localization.dart';
 import 'package:immich_mobile/domain/models/album/album.model.dart';
 import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
+import 'package:immich_mobile/domain/models/time_range.model.dart';
 import 'package:immich_mobile/domain/models/timeline.model.dart';
 import 'package:immich_mobile/domain/services/timeline.service.dart';
 import 'package:immich_mobile/infrastructure/entities/local_asset.entity.dart';
@@ -20,6 +21,7 @@ class TimelineMapOptions {
   final bool includeArchived;
   final bool withPartners;
   final int relativeDays;
+  final TimeRange timeRange;
 
   const TimelineMapOptions({
     required this.bounds,
@@ -27,6 +29,7 @@ class TimelineMapOptions {
     this.includeArchived = false,
     this.withPartners = false,
     this.relativeDays = 0,
+    this.timeRange = const TimeRange(),
   });
 }
 
@@ -552,8 +555,21 @@ class DriftTimelineRepository extends DriftDatabaseRepository {
       query.where(_db.remoteAssetEntity.isFavorite.equals(true));
     }
 
-    if (options.relativeDays != 0) {
+    final timeRange = options.timeRange;
+
+    final hasCustomRange = timeRange.from != null || timeRange.to != null;
+
+    if (hasCustomRange) {
+      if (timeRange.from != null) {
+        query.where(_db.remoteAssetEntity.createdAt.isBiggerOrEqualValue(timeRange.from!));
+      }
+
+      if (timeRange.to != null) {
+        query.where(_db.remoteAssetEntity.createdAt.isSmallerOrEqualValue(timeRange.to!));
+      }
+    } else if (options.relativeDays > 0) {
       final cutoffDate = DateTime.now().toUtc().subtract(Duration(days: options.relativeDays));
+
       query.where(_db.remoteAssetEntity.createdAt.isBiggerOrEqualValue(cutoffDate));
     }
 
@@ -594,8 +610,21 @@ class DriftTimelineRepository extends DriftDatabaseRepository {
       query.where(_db.remoteAssetEntity.isFavorite.equals(true));
     }
 
-    if (options.relativeDays != 0) {
+    final timeRange = options.timeRange;
+
+    final hasCustomRange = timeRange.from != null || timeRange.to != null;
+
+    if (hasCustomRange) {
+      if (timeRange.from != null) {
+        query.where(_db.remoteAssetEntity.createdAt.isBiggerOrEqualValue(timeRange.from!));
+      }
+
+      if (timeRange.to != null) {
+        query.where(_db.remoteAssetEntity.createdAt.isSmallerOrEqualValue(timeRange.to!));
+      }
+    } else if (options.relativeDays > 0) {
       final cutoffDate = DateTime.now().toUtc().subtract(Duration(days: options.relativeDays));
+
       query.where(_db.remoteAssetEntity.createdAt.isBiggerOrEqualValue(cutoffDate));
     }
 

mobile/lib/presentation/widgets/map/map.state.dart

@@ -1,11 +1,13 @@
 import 'package:flutter/material.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:immich_mobile/domain/models/events.model.dart';
+import 'package:immich_mobile/domain/models/time_range.model.dart';
 import 'package:immich_mobile/domain/utils/event_stream.dart';
 import 'package:immich_mobile/infrastructure/repositories/timeline.repository.dart';
 import 'package:immich_mobile/providers/infrastructure/map.provider.dart';
 import 'package:immich_mobile/providers/infrastructure/settings.provider.dart';
 import 'package:immich_mobile/providers/map/map_state.provider.dart';
+import 'package:immich_mobile/utils/option.dart';
 import 'package:maplibre_gl/maplibre_gl.dart';
 
 class MapState {
@@ -15,6 +17,7 @@ class MapState {
   final bool includeArchived;
   final bool withPartners;
   final int relativeDays;
+  final TimeRange timeRange;
 
   const MapState({
     this.themeMode = ThemeMode.system,
@@ -23,6 +26,7 @@ class MapState {
     this.includeArchived = false,
     this.withPartners = false,
     this.relativeDays = 0,
+    this.timeRange = const TimeRange(),
   });
 
   @override
@@ -40,6 +44,7 @@ class MapState {
     bool? includeArchived,
     bool? withPartners,
     int? relativeDays,
+    TimeRange? timeRange,
   }) {
     return MapState(
       bounds: bounds ?? this.bounds,
@@ -48,6 +53,7 @@ class MapState {
       includeArchived: includeArchived ?? this.includeArchived,
       withPartners: withPartners ?? this.withPartners,
       relativeDays: relativeDays ?? this.relativeDays,
+      timeRange: timeRange ?? this.timeRange,
     );
   }
 
@@ -57,6 +63,7 @@ class MapState {
     includeArchived: includeArchived,
     withPartners: withPartners,
     relativeDays: relativeDays,
+    timeRange: timeRange,
   );
 }
 
@@ -103,6 +110,24 @@ class MapStateNotifier extends Notifier<MapState> {
     EventStream.shared.emit(const MapMarkerReloadEvent());
   }
 
+  void setCustomTimeRange(TimeRange range) {
+    ref.read(settingsProvider).write(.mapCustomFrom, range.from);
+    ref.read(settingsProvider).write(.mapCustomTo, range.to);
+    state = state.copyWith(timeRange: range);
+    EventStream.shared.emit(const MapMarkerReloadEvent());
+  }
+
+  Option<DateTime> parseDateOption(String s) {
+    try {
+      if (s.trim().isEmpty) {
+        return const Option.none();
+      }
+      return Option.some(DateTime.parse(s));
+    } catch (_) {
+      return const Option.none();
+    }
+  }
+
   @override
   MapState build() {
     final mapConfig = ref.read(appConfigProvider.select((config) => config.map));
@@ -113,6 +138,7 @@ class MapStateNotifier extends Notifier<MapState> {
       withPartners: mapConfig.withPartners,
       relativeDays: mapConfig.relativeDays,
       bounds: LatLngBounds(northeast: const LatLng(0, 0), southwest: const LatLng(0, 0)),
+      timeRange: TimeRange(from: mapConfig.customFrom, to: mapConfig.customTo),
     );
   }
 }

mobile/lib/presentation/widgets/map/map_settings_sheet.dart

@@ -1,21 +1,39 @@
 import 'package:flutter/material.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:immich_mobile/domain/models/time_range.model.dart';
 import 'package:immich_mobile/extensions/translate_extensions.dart';
+import 'package:immich_mobile/generated/translations.g.dart';
 import 'package:immich_mobile/presentation/widgets/map/map.state.dart';
+import 'package:immich_mobile/widgets/map/map_settings/map_custom_time_range.dart';
 import 'package:immich_mobile/widgets/map/map_settings/map_settings_list_tile.dart';
 import 'package:immich_mobile/widgets/map/map_settings/map_settings_time_dropdown.dart';
 import 'package:immich_mobile/widgets/map/map_settings/map_theme_picker.dart';
 
-class DriftMapSettingsSheet extends HookConsumerWidget {
+class DriftMapSettingsSheet extends ConsumerStatefulWidget {
   const DriftMapSettingsSheet({super.key});
 
   @override
-  Widget build(BuildContext context, WidgetRef ref) {
+  ConsumerState<DriftMapSettingsSheet> createState() => _DriftMapSettingsSheetState();
+}
+
+class _DriftMapSettingsSheetState extends ConsumerState<DriftMapSettingsSheet> {
+  late bool useCustomRange;
+
+  @override
+  void initState() {
+    super.initState();
+    final mapState = ref.read(mapStateProvider);
+    final timeRange = mapState.timeRange;
+    useCustomRange = timeRange.from != null || timeRange.to != null;
+  }
+
+  @override
+  Widget build(BuildContext context) {
     final mapState = ref.watch(mapStateProvider);
 
     return DraggableScrollableSheet(
       expand: false,
-      initialChildSize: 0.6,
+      initialChildSize: useCustomRange ? 0.7 : 0.6,
       builder: (ctx, scrollController) => SingleChildScrollView(
         controller: scrollController,
         child: Card(
@@ -47,10 +65,41 @@ class DriftMapSettingsSheet extends HookConsumerWidget {
                 selected: mapState.withPartners,
                 onChanged: (withPartners) => ref.read(mapStateProvider.notifier).switchWithPartners(withPartners),
               ),
-              MapTimeDropDown(
+              if (useCustomRange) ...[
-                relativeTime: mapState.relativeDays,
+                MapTimeRange(
-                onTimeChange: (time) => ref.read(mapStateProvider.notifier).setRelativeTime(time),
+                  timeRange: mapState.timeRange,
-              ),
+                  onChanged: (range) {
+                    ref.read(mapStateProvider.notifier).setCustomTimeRange(range);
+                  },
+                ),
+                Align(
+                  alignment: Alignment.centerLeft,
+                  child: TextButton(
+                    onPressed: () => setState(() {
+                      useCustomRange = false;
+                      ref.read(mapStateProvider.notifier).setRelativeTime(0);
+                      ref.read(mapStateProvider.notifier).setCustomTimeRange(const TimeRange());
+                    }),
+                    child: Text(context.t.remove_custom_date_range),
+                  ),
+                ),
+              ] else ...[
+                MapTimeDropDown(
+                  relativeTime: mapState.relativeDays,
+                  onTimeChange: (time) => ref.read(mapStateProvider.notifier).setRelativeTime(time),
+                ),
+                Align(
+                  alignment: Alignment.centerLeft,
+                  child: TextButton(
+                    onPressed: () => setState(() {
+                      useCustomRange = true;
+                      ref.read(mapStateProvider.notifier).setRelativeTime(0);
+                      ref.read(mapStateProvider.notifier).setCustomTimeRange(const TimeRange());
+                    }),
+                    child: Text(context.t.use_custom_date_range),
+                  ),
+                ),
+              ],
               const SizedBox(height: 20),
             ],
           ),

mobile/lib/utils/option.dart

@@ -32,6 +32,17 @@ sealed class Option<T> {
     None() => onNone(),
   };
 
+  Option<U> flatMap<U>(Option<U> Function(T value) f) => switch (this) {
+    Some(:final value) => f(value),
+    None() => const Option.none(),
+  };
+
+  void ifPresent(void Function(T value) f) {
+    if (this case Some(:final value)) {
+      f(value);
+    }
+  }
+
   @override
   String toString() => switch (this) {
     Some(:final value) => 'Some($value)',

mobile/lib/widgets/map/map_settings/map_custom_time_range.dart

@@ -0,0 +1,73 @@
+import 'package:easy_localization/easy_localization.dart';
+import 'package:flutter/material.dart';
+import 'package:immich_mobile/domain/models/time_range.model.dart';
+import 'package:immich_mobile/generated/translations.g.dart';
+import 'package:immich_mobile/utils/option.dart';
+
+class MapTimeRange extends StatelessWidget {
+  const MapTimeRange({super.key, required this.timeRange, required this.onChanged});
+
+  final TimeRange timeRange;
+  final Function(TimeRange) onChanged;
+
+  @override
+  Widget build(BuildContext context) {
+    return Column(
+      mainAxisSize: MainAxisSize.min,
+      children: [
+        ListTile(
+          title: Text(context.t.date_after),
+          subtitle: Text(
+            timeRange.from != null
+                ? DateFormat.yMMMd(context.locale.toLanguageTag()).add_jm().format(timeRange.from!)
+                : context.t.not_set,
+          ),
+          trailing: timeRange.from != null
+              ? IconButton(icon: const Icon(Icons.close), onPressed: () => onChanged(timeRange.clearFrom()))
+              : null,
+          onTap: () async {
+            final initial = timeRange.from ?? DateTime.now();
+            final currentTo = timeRange.to;
+
+            final picked = await showDatePicker(
+              context: context,
+              initialDate: currentTo != null && initial.isAfter(currentTo) ? currentTo : initial,
+              firstDate: DateTime(1970),
+              lastDate: currentTo ?? DateTime.now(),
+            );
+
+            if (picked != null) {
+              onChanged(timeRange.copyWith(from: Option.some(picked)));
+            }
+          },
+        ),
+        ListTile(
+          title: Text(context.t.date_before),
+          subtitle: Text(
+            timeRange.to != null
+                ? DateFormat.yMMMd(context.locale.toLanguageTag()).add_jm().format(timeRange.to!)
+                : context.t.not_set,
+          ),
+          trailing: timeRange.to != null
+              ? IconButton(icon: const Icon(Icons.close), onPressed: () => onChanged(timeRange.clearTo()))
+              : null,
+          onTap: () async {
+            final initial = timeRange.to ?? DateTime.now();
+            final currentFrom = timeRange.from;
+
+            final picked = await showDatePicker(
+              context: context,
+              initialDate: currentFrom != null && initial.isBefore(currentFrom) ? currentFrom : initial,
+              firstDate: currentFrom ?? DateTime(1970),
+              lastDate: DateTime.now(),
+            );
+
+            if (picked != null) {
+              onChanged(timeRange.copyWith(to: Option.some(picked)));
+            }
+          },
+        ),
+      ],
+    );
+  }
+}

mobile/test/presentation/widgets/timeline/timeline_args_test.dart

@@ -25,6 +25,8 @@ class _FrozenBucketService implements TimelineService {
 }
 
 class _EmptyBucketService implements TimelineService {
+  const _EmptyBucketService();
+
   @override
   Stream<List<Bucket>> Function() get watchBuckets =>
       () => Stream.value(const []);
@@ -109,7 +111,7 @@ void main() {
     await tester.pumpWidget(
       ProviderScope(
         overrides: [
-          timelineServiceProvider.overrideWithValue(_EmptyBucketService()),
+          timelineServiceProvider.overrideWithValue(const _EmptyBucketService()),
           appConfigProvider.overrideWithValue(const AppConfig()),
         ],
         child: MaterialApp(

mobile/test/unit/utils/value_codec_test.dart

@@ -0,0 +1,99 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:immich_mobile/domain/models/value_codec.dart';
+
+enum _Fruit { apple, banana, cherry }
+
+void main() {
+  group('MapCodec', () {
+    group('encode', () {
+      test('serializes an empty map to an empty JSON object', () {
+        const codec = MapCodec<String, String>(PrimitiveCodec.string, PrimitiveCodec.string);
+        expect(codec.encode({}), '{}');
+      });
+
+      test('encodes a string-to-string map as a JSON object', () {
+        const codec = MapCodec<String, String>(PrimitiveCodec.string, PrimitiveCodec.string);
+        expect(codec.encode({'a': '1', 'b': '2'}), '{"a":"1","b":"2"}');
+      });
+
+      test('stringifies non-string values via the value codec', () {
+        const codec = MapCodec<String, int>(PrimitiveCodec.string, PrimitiveCodec.integer);
+        expect(codec.encode({'x': 10, 'y': 20}), '{"x":"10","y":"20"}');
+      });
+
+      test('stringifies non-string keys via the key codec', () {
+        const codec = MapCodec<int, String>(PrimitiveCodec.integer, PrimitiveCodec.string);
+        expect(codec.encode({1: 'one', 2: 'two'}), '{"1":"one","2":"two"}');
+      });
+    });
+
+    group('decode', () {
+      test('reconstructs a string-to-string map', () {
+        const codec = MapCodec<String, String>(PrimitiveCodec.string, PrimitiveCodec.string);
+        expect(codec.decode('{"a":"1","b":"2"}'), {'a': '1', 'b': '2'});
+      });
+
+      test('parses values back to their domain type', () {
+        const codec = MapCodec<String, int>(PrimitiveCodec.string, PrimitiveCodec.integer);
+        expect(codec.decode('{"x":"10","y":"20"}'), {'x': 10, 'y': 20});
+      });
+
+      test('parses keys back to their domain type', () {
+        const codec = MapCodec<int, String>(PrimitiveCodec.integer, PrimitiveCodec.string);
+        expect(codec.decode('{"1":"one","2":"two"}'), {1: 'one', 2: 'two'});
+      });
+
+      test('returns an empty map for an empty JSON object', () {
+        const codec = MapCodec<String, String>(PrimitiveCodec.string, PrimitiveCodec.string);
+        expect(codec.decode('{}'), isEmpty);
+      });
+
+      test('returns an empty map when the payload is not valid JSON', () {
+        const codec = MapCodec<String, String>(PrimitiveCodec.string, PrimitiveCodec.string);
+        expect(codec.decode('not json'), isEmpty);
+      });
+
+      test('returns an empty map when the JSON root is not an object', () {
+        const codec = MapCodec<String, String>(PrimitiveCodec.string, PrimitiveCodec.string);
+        expect(codec.decode('[]'), isEmpty);
+        expect(codec.decode('"a string"'), isEmpty);
+        expect(codec.decode('42'), isEmpty);
+      });
+
+      test('skips entries whose value is not a JSON string, keeping the rest', () {
+        const codec = MapCodec<String, int>(PrimitiveCodec.string, PrimitiveCodec.integer);
+        expect(codec.decode('{"x":1,"y":"20"}'), {'y': 20});
+      });
+
+      test('skips entries whose value is a nested object, keeping the rest', () {
+        const codec = MapCodec<String, String>(PrimitiveCodec.string, PrimitiveCodec.string);
+        expect(codec.decode('{"a":{"nested":"value"},"b":"ok"}'), {'b': 'ok'});
+      });
+
+      test('returns an empty map when every entry is malformed', () {
+        const codec = MapCodec<String, int>(PrimitiveCodec.string, PrimitiveCodec.integer);
+        expect(codec.decode('{"x":1,"y":2}'), isEmpty);
+      });
+    });
+
+    group('round trip', () {
+      test('preserves a primitive map through encode then decode', () {
+        const codec = MapCodec<String, int>(PrimitiveCodec.string, PrimitiveCodec.integer);
+        const original = {'one': 1, 'two': 2, 'three': 3};
+        expect(codec.decode(codec.encode(original)), original);
+      });
+
+      test('preserves an enum-valued map by composing with EnumCodec', () {
+        const codec = MapCodec<String, _Fruit>(PrimitiveCodec.string, EnumCodec(_Fruit.values));
+        const original = {'breakfast': _Fruit.banana, 'snack': _Fruit.apple};
+        expect(codec.decode(codec.encode(original)), original);
+      });
+
+      test('preserves a DateTime-valued map by composing with DateTimeCodec', () {
+        const codec = MapCodec<String, DateTime>(PrimitiveCodec.string, DateTimeCodec());
+        final original = {'created': DateTime.utc(2024, 1, 1, 12, 30)};
+        expect(codec.decode(codec.encode(original)), original);
+      });
+    });
+  });
+}