Fix characteristic value listener and add tests (#168)

* Improve characteristic value listener

* Implement characteristic tests

* Bump version and update changelog

test/ble_characteristic_test.dart

@@ -0,0 +1,127 @@
+import 'dart:async';
+import 'package:flutter/foundation.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:universal_ble/universal_ble.dart';
+import 'universal_ble_test_mock.dart';
+
+String serviceId = "180a";
+String characteristicId = "202a";
+String mockDeviceId = "mock_id";
+BleCharacteristic mockBleCharacteristic = BleCharacteristic.withMetaData(
+  deviceId: mockDeviceId,
+  serviceId: serviceId,
+  uuid: characteristicId,
+  properties: CharacteristicProperty.values,
+);
+BleService mockBleService = BleService(serviceId, [mockBleCharacteristic]);
+
+void main() {
+  late UniversalBlePlatform platform;
+  setUp(() {
+    platform = _UniversalBleMock();
+    UniversalBle.setInstance(platform);
+  });
+
+  group('BleCharacteristic Tests', () {
+    test("DiscoverServices test", () async {
+      debugPrint("Discovering services");
+      List<BleService> services =
+          await UniversalBle.discoverServices(mockDeviceId);
+      expect(services.length, 1);
+
+      BleService service = services.first;
+      expect(BleUuidParser.compareStrings(service.uuid, serviceId), true);
+      expect(service.characteristics.length, 1);
+
+      BleCharacteristic characteristic = service.characteristics.first;
+      expect(
+        BleUuidParser.compareStrings(characteristic.uuid, characteristicId),
+        true,
+      );
+      expect(characteristic.metaData?.deviceId, mockDeviceId);
+      expect(
+        BleUuidParser.compareStrings(
+          characteristic.metaData!.serviceId,
+          serviceId,
+        ),
+        true,
+      );
+    });
+
+    test("Subscription Test", () async {
+      BleCharacteristic characteristic = mockBleCharacteristic;
+
+      debugPrint("Subscribing to char");
+      await characteristic.notifications.subscribe();
+
+      bool gotEvent = false;
+      var subscription = characteristic.notifications.listen((data) {
+        debugPrint("Received CharValue: $data");
+        gotEvent = true;
+      });
+
+      await Future.delayed(Duration(seconds: 1));
+      await characteristic.notifications.unsubscribe();
+      debugPrint("Unsubscribed from char");
+
+      subscription.cancel();
+      expect(gotEvent, true);
+    });
+  });
+
+  test("Write/Read Value Test", () async {
+    BleCharacteristic characteristic = mockBleCharacteristic;
+    Uint8List charValue = Uint8List.fromList([0x01, 0x02]);
+    await characteristic.write(charValue);
+    debugPrint("Write Succeed");
+
+    var readResult = await characteristic.read();
+    debugPrint("Read Succeed");
+    expect(readResult, charValue);
+  });
+}
+
+class _UniversalBleMock extends UniversalBlePlatformMock {
+  Timer? notifierTimer;
+  Uint8List? charValue;
+
+  @override
+  Future<List<BleService>> discoverServices(String deviceId) async {
+    return <BleService>[mockBleService];
+  }
+
+  @override
+  Future<void> setNotifiable(String deviceId, String service,
+      String characteristic, BleInputProperty bleInputProperty) async {
+    if (bleInputProperty == BleInputProperty.disabled) {
+      notifierTimer?.cancel();
+      notifierTimer = null;
+      return;
+    }
+
+    notifierTimer ??= Timer.periodic(Duration(milliseconds: 500), (timer) {
+      updateCharacteristicValue(
+        deviceId,
+        characteristic,
+        Uint8List.fromList([1, 2, 3]),
+      );
+    });
+  }
+
+  @override
+  Future<void> writeValue(
+      String deviceId,
+      String service,
+      String characteristic,
+      Uint8List value,
+      BleOutputProperty bleOutputProperty) async {
+    charValue = value;
+  }
+
+  @override
+  Future<Uint8List> readValue(
+      String deviceId, String service, String characteristic,
+      {Duration? timeout}) async {
+    return charValue ?? Uint8List(0);
+  }
+}

test/universal_ble_test_mock.dart

@@ -0,0 +1,98 @@
+import 'dart:typed_data';
+import 'package:universal_ble/universal_ble.dart';
+
+abstract class UniversalBlePlatformMock extends UniversalBlePlatform {
+  @override
+  Future<void> connect(String deviceId, {Duration? connectionTimeout}) {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<bool> disableBluetooth() {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<void> disconnect(String deviceId) {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<List<BleService>> discoverServices(String deviceId) {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<bool> enableBluetooth() {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<AvailabilityState> getBluetoothAvailabilityState() {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<BleConnectionState> getConnectionState(String deviceId) {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<List<BleDevice>> getSystemDevices(List<String>? withServices) {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<bool> isPaired(String deviceId) {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<bool> pair(String deviceId) {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<Uint8List> readValue(
+      String deviceId, String service, String characteristic,
+      {Duration? timeout}) {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<int> requestMtu(String deviceId, int expectedMtu) {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<void> setNotifiable(String deviceId, String service,
+      String characteristic, BleInputProperty bleInputProperty) {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<void> startScan(
+      {ScanFilter? scanFilter, PlatformConfig? platformConfig}) {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<void> stopScan() {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<void> unpair(String deviceId) {
+    throw UnimplementedError();
+  }
+
+  @override
+  Future<void> writeValue(
+      String deviceId,
+      String service,
+      String characteristic,
+      Uint8List value,
+      BleOutputProperty bleOutputProperty) {
+    throw UnimplementedError();
+  }
+}