Add unit test album list filter screen

lib/src/features/albums/presentation/albums_list/albums_list_filter_screen.dart

@@ -26,7 +26,7 @@ class AlbumsFilterScreen extends StatelessWidget {
           return ListView(
             children: [
               DropdownAlbumType(
-                value: state.discTypes ?? '',
+                value: state.discTypes ?? 'Unknown',
                 onChanged: (value) =>
                     onAlbumTypesChanged?.call(value) ??
                     ref

test/src/features/albums/presentation/albums_list/albums_list_filter_screen_robot.dart

@@ -0,0 +1,56 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:vocadb_app/src/features/albums/presentation/albums_list/albums_list_filter_screen.dart';
+import 'package:vocadb_app/src/features/albums/presentation/widgets/dropdown_album_sort.dart';
+import 'package:vocadb_app/src/features/albums/presentation/widgets/dropdown_album_type.dart';
+
+class AlbumsListFilterScreenRobot {
+  final WidgetTester tester;
+
+  AlbumsListFilterScreenRobot(this.tester);
+
+  Future<void> pumpAlbumsListFilterScreen({
+    Function(String?)? onAlbumsTypesChanged,
+    Function(String?)? onSortChanged,
+  }) async {
+    await tester.pumpWidget(
+      ProviderScope(
+        child: MaterialApp(
+          home: AlbumsFilterScreen(
+            onAlbumTypesChanged: onAlbumsTypesChanged,
+            onSortChanged: onSortChanged,
+          ),
+        ),
+      ),
+    );
+  }
+
+  Future<void> selectAlbumTypes(String value) async {
+    final albumTypeDropdownBtnFinder =
+        find.byKey(DropdownAlbumType.dropdownKey);
+    expect(albumTypeDropdownBtnFinder, findsOneWidget);
+
+    await tester.tap(albumTypeDropdownBtnFinder);
+    await tester.pump();
+
+    final selectedFinder = find.text(value).last;
+    expect(selectedFinder, findsOneWidget);
+    await tester.tap(selectedFinder);
+    await tester.pump();
+  }
+
+  Future<void> selectSort(String value) async {
+    final albumSortDropdownBtnFinder =
+        find.byKey(DropdownAlbumSort.dropdownKey);
+    expect(albumSortDropdownBtnFinder, findsOneWidget);
+
+    await tester.tap(albumSortDropdownBtnFinder);
+    await tester.pump();
+
+    final selectedFinder = find.text(value).last;
+    expect(selectedFinder, findsOneWidget);
+    await tester.tap(selectedFinder);
+    await tester.pump();
+  }
+}

test/src/features/albums/presentation/albums_list/albums_list_screen_test.dart

@@ -0,0 +1,31 @@
+import 'package:flutter_test/flutter_test.dart';
+
+import 'albums_list_filter_screen_robot.dart';
+
+void main() {
+  group('albums filter screen', () {
+    testWidgets('change album type', (tester) async {
+      String? selectedValue;
+      final r = AlbumsListFilterScreenRobot(tester);
+
+      await r.pumpAlbumsListFilterScreen(
+        onAlbumsTypesChanged: (value) => selectedValue = value,
+      );
+
+      await r.selectAlbumTypes('E.P.');
+      expect(selectedValue, 'EP');
+    });
+
+    testWidgets('change album sort', (tester) async {
+      String? selectedValue;
+      final r = AlbumsListFilterScreenRobot(tester);
+
+      await r.pumpAlbumsListFilterScreen(
+        onAlbumsTypesChanged: (value) => selectedValue = value,
+      );
+
+      await r.selectSort('Addition date');
+      expect(selectedValue, 'AdditionDate');
+    });
+  });
+}