Update test

test/flutter_usb_serial_test.dart

@@ -1,29 +1,28 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_usb_serial/flutter_usb_serial.dart';
-import 'package:flutter_usb_serial/flutter_usb_serial_platform_interface.dart';
 import 'package:flutter_usb_serial/flutter_usb_serial_method_channel.dart';
-import 'package:plugin_platform_interface/plugin_platform_interface.dart';
-
-class MockFlutterUsbSerialPlatform
-    with MockPlatformInterfaceMixin
-    implements FlutterUsbSerialPlatform {
-
-  @override
-  Future<String?> getPlatformVersion() => Future.value('42');
-}
 
 void main() {
-  final FlutterUsbSerialPlatform initialPlatform = FlutterUsbSerialPlatform.instance;
-
-  test('$MethodChannelFlutterUsbSerial is the default instance', () {
-    expect(initialPlatform, isInstanceOf<MethodChannelFlutterUsbSerial>());
+  test('$MethodChannelFlutterUsbSerial can be constructed', () {
+    expect(MethodChannelFlutterUsbSerial(), isA<MethodChannelFlutterUsbSerial>());
   });
 
-  test('getPlatformVersion', () async {
-    FlutterUsbSerial flutterUsbSerialPlugin = FlutterUsbSerial();
-    MockFlutterUsbSerialPlatform fakePlatform = MockFlutterUsbSerialPlatform();
-    FlutterUsbSerialPlatform.instance = fakePlatform;
+  test('UsbSerialDevice maps fields from method channel payloads', () {
+    final device = UsbSerialDevice.fromMap({
+      'deviceId': 7,
+      'vendorId': 0x1234,
+      'productId': 0x5678,
+      'deviceName': 'Adapter',
+      'manufacturerName': 'Acme',
+      'serialNumber': 'SN-42',
+    });
 
-    expect(await flutterUsbSerialPlugin.getPlatformVersion(), '42');
+    expect(device.deviceId, 7);
+    expect(device.vendorId, 0x1234);
+    expect(device.productId, 0x5678);
+    expect(device.deviceName, 'Adapter');
+    expect(device.manufacturerName, 'Acme');
+    expect(device.serialNumber, 'SN-42');
+    expect(device.toMap()['deviceId'], 7);
   });
 }