Mockito深桩法

Question

我只是不明白为什么我在scan（）中的存根方法scanBleDevices（）会返回模拟对象。

蓝牙适配器：

fun scan(scanTimeoutMillis: Long): Flowable<Packet> = bluetoothClient
.scanBleDevices(ScanSettings.Builder()
.setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY).build())....

测试：

val spyBleAdapter = Mockito.spy(viewModel.scanBluetoothFlowabler.bluetoothAdapter)
viewModel.scanBluetoothFlowabler.bluetoothAdapter = spyBleAdapter

val spyBleClient = Mockito.spy(spyBleAdapter.bluetoothClient)
spyBleAdapter.bluetoothClient = spyBleClient

whenever(spyBleClient.scanBleDevices(fakeScanSettings))
        .thenReturn(Observable.just(mockScanResult))

// here it returns mockScanResult
val scanBleDevices = spyBleClient.scanBleDevices(fakeScanSettings) 

//  scanBleDevices() inside scan() is not stubbed so i got not implemented exception
val scan = spyBleAdapter.scan(ArgumentMatchers.anyLong())

我在做什么错了？