doormile_milderapp/test/offline_banner_test.dart

import 'package:flutter/material.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';
import 'package:flutter_test/flutter_test.dart';

import 'package:miler/views/offline/offline_banner.dart';
import 'package:miler/views/helpers/constants/Colorconstants.dart';

/// ── Losing signal must not take the job away ──
///
/// Connectivity used to stack an opaque full-screen page over the entire app.
/// A rider at a doorstep in a basement lost the address, the customer, the
/// parcel count and the OTP field — while holding the parcel. Everything he
/// needs at the door was already fetched; the network is needed to *report* the
/// stop, not to work it.
void main() {
  Future<void> pump(WidgetTester tester, {required bool offline}) async {
    tester.view.physicalSize = const Size(390 * 3, 844 * 3);
    tester.view.devicePixelRatio = 3.0;
    addTearDown(tester.view.reset);

    await tester.pumpWidget(
      ScreenUtilInit(
        designSize: const Size(390, 844),
        builder: (_, _) => MaterialApp(
          home: OfflineScope(
            offline: offline,
            child: Scaffold(
              body: Column(
                children: const [
                  Text('45, Lake View Apartments'),
                  Text('Priya Sharma'),
                  Text('Delivery OTP'),
                ],
              ),
            ),
          ),
        ),
      ),
    );
    await tester.pumpAndSettle();
  }

  testWidgets('the job stays on screen while offline', (tester) async {
    await pump(tester, offline: true);

    // The four things a rider cannot do the stop without.
    expect(find.text('45, Lake View Apartments'), findsOneWidget);
    expect(find.text('Priya Sharma'), findsOneWidget);
    expect(find.text('Delivery OTP'), findsOneWidget);
    expect(find.byType(OfflineBanner), findsOneWidget);
  });

  testWidgets('the strip takes its own row — it never covers content', (
    tester,
  ) async {
    await pump(tester, offline: true);

    // A Column, not a Stack, on purpose: a floating bar over the page would sit
    // on top of the OTP box, which is worse than the blocker it replaced.
    final strip = tester.getRect(find.byType(OfflineBanner));
    final firstContent = tester.getRect(find.text('45, Lake View Apartments'));
    expect(strip.bottom, lessThanOrEqualTo(firstContent.top));
  });

  testWidgets('it is thin enough to cost the job nothing', (tester) async {
    await pump(tester, offline: true);
    // Roughly one line plus padding. A "banner" that eats 15% of an 844pt
    // screen is a blocker with a nicer name.
    expect(tester.getSize(find.byType(OfflineBanner)).height, lessThan(64));
  });

  testWidgets('it says what happens next, not just what is wrong', (
    tester,
  ) async {
    await pump(tester, offline: true);
    final text = tester
        .widgetList<Text>(
          find.descendant(
            of: find.byType(OfflineBanner),
            matching: find.byType(Text),
          ),
        )
        .first
        .data!;
    expect(text, contains('Offline'));
    expect(text.toLowerCase(), contains('sync'));
  });

  testWidgets('online, it occupies no space at all', (tester) async {
    await pump(tester, offline: false);
    expect(find.byType(OfflineBanner), findsNothing);
    expect(
      tester.getRect(find.text('45, Lake View Apartments')).top,
      lessThan(20),
    );
  });

  testWidgets('the strip carries a readable label on its fill', (tester) async {
    await pump(tester, offline: true);
    final material = tester.widget<Material>(
      find
          .descendant(
            of: find.byType(OfflineBanner),
            matching: find.byType(Material),
          )
          .first,
    );
    // `warning`, which the contrast contract holds to 4.5:1 behind white.
    expect(material.color, ColorConstants.warning);
  });
}