我在单元测试我的控制器时遇到问题，并收到错误“Nest无法解析我的服务的依赖项”。
为了最大限度的覆盖，我想对控制器和相应的服务进行单元测试，并模拟外部依赖，如mongoose连接。同样，我已经尝试了下面链接中提到的建议，但没有找到任何运气：
https://github.com/nestjs/nest/issues/194#issuecomment-342219043
请在下面找到我的代码：

export const deviceProviders = [
    {
        provide: 'devices',
        useFactory: (connection: Connection) => connection.model('devices', DeviceSchema),
        inject: ['DbConnectionToken'],
    },
];

export class DeviceService extends BaseService {
    constructor(@InjectModel('devices') private readonly _deviceModel: Model<Device>) {
        super();
    }

    async getDevices(group): Promise<any> {
        try {
            return await this._deviceModel.find({ Group: group }).exec();
        } catch (error) {
            return Promise.reject(error);
        }
    }
}

@Controller()
export class DeviceController {
    constructor(private readonly deviceService: DeviceService) {
    }

   @Get(':group')
   async getDevices(@Res() response, @Param('group') group): Promise<any> {
        try {
            const result = await this.deviceService.getDevices(group);
            return response.send(result);
        }
        catch (err) {
            return response.status(422).send(err);
        }
    }
}

@Module({
    imports: [MongooseModule.forFeature([{ name: 'devices', schema: DeviceSchema }])],
    controllers: [DeviceController],
    components: [DeviceService, ...deviceProviders],
})
export class DeviceModule { }

单元测试：

describe('DeviceController', () => {
    let deviceController: DeviceController;
    let deviceService: DeviceService;

    const response = {
        send: (body?: any) => { },
        status: (code: number) => response,
    };

    beforeEach(async () => {
        const module = await Test.createTestingModule({
            controllers: [DeviceController],
            components: [DeviceService, ...deviceProviders],
        }).compile();

        deviceService = module.get<DeviceService>(DeviceService);
        deviceController = module.get<DeviceController>(DeviceController);
    });

    describe('getDevices()', () => {
        it('should return an array of devices', async () => {
            const result = [{
                Group: 'group_abc',
                DeviceId: 'device_abc',
            },
            {
                Group: 'group_xyz',
                DeviceId: 'device_xyz',
            }];
            jest.spyOn(deviceService, 'getDevices').mockImplementation(() => result);

            expect(await deviceController.getDevices(response, null)).toBe(result);
        });
    });
});

当我运行上面的测试用例时，我得到了两个错误：
Nest无法解析DeviceService（？）的依赖项。请确保索引[0]处的参数在当前上下文中可用。
无法对基元值执行spyOn;未定义给定