abawo-bt-app/test/service/dfu_preflight_test.dart

import 'package:abawo_bt_app/controller/bluetooth.dart';
import 'package:abawo_bt_app/model/shifter_types.dart';
import 'package:abawo_bt_app/service/shifter_service.dart';
import 'package:anyhow/anyhow.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  group('ShifterService.runDfuPreflight', () {
    test('fails when no active button connection exists', () async {
      final adapter = _FakeDfuPreflightBluetoothAdapter(
        currentConnectionState: (ConnectionStatus.disconnected, null),
        mtuResult: Ok(128),
      );
      final service = ShifterService(
        buttonDeviceId: 'target-device',
        dfuPreflightBluetooth: adapter,
      );

      final result = await service.runDfuPreflight();

      expect(result.isOk(), isTrue);
      final preflight = result.unwrap();
      expect(preflight.canStart, isFalse);
      expect(preflight.failureReason,
          DfuPreflightFailureReason.deviceNotConnected);
      expect(adapter.requestMtuCallCount, 0);
    });

    test('fails when connected to a different button', () async {
      final adapter = _FakeDfuPreflightBluetoothAdapter(
        currentConnectionState: (ConnectionStatus.connected, 'wrong-device'),
        mtuResult: Ok(128),
      );
      final service = ShifterService(
        buttonDeviceId: 'target-device',
        dfuPreflightBluetooth: adapter,
      );

      final result = await service.runDfuPreflight();

      expect(result.isOk(), isTrue);
      final preflight = result.unwrap();
      expect(preflight.canStart, isFalse);
      expect(preflight.failureReason,
          DfuPreflightFailureReason.wrongConnectedDevice);
      expect(adapter.requestMtuCallCount, 0);
    });

    test('fails when MTU negotiation fails', () async {
      final adapter = _FakeDfuPreflightBluetoothAdapter(
        currentConnectionState: (ConnectionStatus.connected, 'target-device'),
        mtuResult: bail('adapter rejected mtu request'),
      );
      final service = ShifterService(
        buttonDeviceId: 'target-device',
        dfuPreflightBluetooth: adapter,
      );

      final result = await service.runDfuPreflight(requestedMtu: 247);

      expect(result.isOk(), isTrue);
      final preflight = result.unwrap();
      expect(preflight.canStart, isFalse);
      expect(
          preflight.failureReason, DfuPreflightFailureReason.mtuRequestFailed);
      expect(preflight.message, contains('adapter rejected mtu request'));
      expect(adapter.requestedMtuValues, [247]);
    });

    test('fails when negotiated MTU is too low for 64-byte frame writes',
        () async {
      final adapter = _FakeDfuPreflightBluetoothAdapter(
        currentConnectionState: (ConnectionStatus.connected, 'target-device'),
        mtuResult: Ok(universalShifterDfuMinimumMtu - 1),
      );
      final service = ShifterService(
        buttonDeviceId: 'target-device',
        dfuPreflightBluetooth: adapter,
      );

      final result = await service.runDfuPreflight();

      expect(result.isOk(), isTrue);
      final preflight = result.unwrap();
      expect(preflight.canStart, isFalse);
      expect(preflight.failureReason, DfuPreflightFailureReason.mtuTooLow);
      expect(preflight.negotiatedMtu, universalShifterDfuMinimumMtu - 1);
      expect(preflight.requiredMtu, universalShifterDfuMinimumMtu);
    });

    test('passes when connected to target and MTU is sufficient', () async {
      final adapter = _FakeDfuPreflightBluetoothAdapter(
        currentConnectionState: (ConnectionStatus.connected, 'target-device'),
        mtuResult: Ok(128),
      );
      final service = ShifterService(
        buttonDeviceId: 'target-device',
        dfuPreflightBluetooth: adapter,
      );

      final result = await service.runDfuPreflight();

      expect(result.isOk(), isTrue);
      final preflight = result.unwrap();
      expect(preflight.canStart, isTrue);
      expect(preflight.failureReason, isNull);
      expect(preflight.negotiatedMtu, 128);
      expect(preflight.requestedMtu, universalShifterDfuPreferredMtu);
    });
  });
}

class _FakeDfuPreflightBluetoothAdapter
    implements DfuPreflightBluetoothAdapter {
  _FakeDfuPreflightBluetoothAdapter({
    required this.currentConnectionState,
    required Result<int> mtuResult,
  }) : _mtuResult = mtuResult;

  @override
  final (ConnectionStatus, String?) currentConnectionState;

  final Result<int> _mtuResult;

  int requestMtuCallCount = 0;
  final List<int> requestedMtuValues = <int>[];

  @override
  Future<Result<int>> requestMtuAndGetValue(
    String deviceId, {
    required int mtu,
  }) async {
    requestMtuCallCount += 1;
    requestedMtuValues.add(mtu);
    return _mtuResult;
  }
}