public async Task StopAsyncWithoutStartAsyncNoops()
        {
            var tcs     = new TaskCompletionSource <object>();
            var service = new MyBackgroundService(tcs.Task);

            await service.StopAsync(CancellationToken.None);
        }
        public async Task StopAsyncStopsBackgroundService()
        {
            var tcs     = new TaskCompletionSource <object>();
            var service = new MyBackgroundService(tcs.Task);

            await service.StartAsync(CancellationToken.None);

            Assert.False(service.ExecuteTask.IsCompleted);

            await service.StopAsync(CancellationToken.None);

            Assert.True(service.ExecuteTask.IsCompleted);
        }