halkyon/packages/halkyon_ui/test/widget/undo_snack_bar_test.dart

import 'package:flutter_test/flutter_test.dart';
import 'package:halkyon_ui/halkyon_ui.dart';
import 'package:material_ui/material_ui.dart';

void main() {
  late int undos;
  late int kept;

  setUp(() {
    undos = 0;
    kept = 0;
  });

  /// Shows "Studyset archived" with a way to undo it.
  Future<void> archive(WidgetTester tester) async {
    await tester.pumpWidget(
      MaterialApp(
        localizationsDelegates: HalkyonUiLocalizations.localizationsDelegates,
        supportedLocales: HalkyonUiLocalizations.supportedLocales,
        home: Scaffold(
          body: Builder(
            builder: (context) => TextButton(
              onPressed: () => showUndoSnackBar(
                context,
                message: 'Studyset archived',
                onUndo: () => undos++,
                onKept: () => kept++,
              ),
              child: const Text('Archive'),
            ),
          ),
        ),
      ),
    );
    await tester.tap(find.text('Archive'));
    await tester.pumpAndSettle();
  }

  testWidgets('offers to undo', (tester) async {
    await archive(tester);
    expect(find.text('Studyset archived'), findsOneWidget);

    await tester.tap(find.text('Undo'));
    await tester.pumpAndSettle();

    expect(undos, 1);
    expect(find.text('Studyset archived'), findsNothing);
  });

  testWidgets('goes by itself after three seconds', (tester) async {
    await archive(tester);

    await tester.pump(const Duration(seconds: 3));
    await tester.pumpAndSettle();

    expect(find.text('Studyset archived'), findsNothing);
    expect(undos, 0);
  });

  testWidgets('tells once it went without Undo, so what waited for it '
      'happens then', (tester) async {
    await archive(tester);
    expect(kept, 0, reason: 'not while it shows');

    await tester.pump(const Duration(seconds: 3));
    await tester.pumpAndSettle();

    expect(kept, 1);
  });

  testWidgets('never tells it was kept once undone', (tester) async {
    await archive(tester);

    await tester.tap(find.text('Undo'));
    await tester.pumpAndSettle();
    await tester.pump(const Duration(seconds: 5));

    expect(kept, 0);
  });
}