How to use CoreBluetooth framework from XCUITest - core-bluetooth

Question

I'm having a project where I have to write automation for Apple Watch & iPhone app. I'm forced to use XCUITest with Swift because Appium is not yet supporting WatchOS as a testing target.
In my tests, at some points, I have to communicate with an external device via BLE. I wanted to use the CoreBluetooth framework, but I got no luck with that. I have a working CoreBT code that I've used to create a simple BLE chat app, but for some reason, that same code is not working when called from the UI test.
The main problem is that I'm not able to get CBCentralManager in a powered state:
[CoreBluetooth] API MISUSE: <CBCentralManager: 0x28175ce00> can only accept this command while in the powered on state
Later I checked the BT authorization state inside the test with cbCentralManager.authorization == .notDetermined, and it confirmed that authorization is not confirmed. That might be a problem why CBCentralManager is not powering up, but I'm not sure how to resolve it. The app I'm testing is able to use BT without any issues (has all permissions).
Is it even possible to use CoreBluetooth from UITests??
This is the test class code:
import CoreBluetooth
import XCTest
let peripheralName = "MY-BLE-DEVICE-NAME"
let service_First = CBUUID(string: "0000ffe0-0000-1000-8000-00805f9b34fb")
let readCharacteristic = CBUUID(string: "0000ffe1-0000-1000-8000-00805f9b34fb")
let writeCharacteristic = CBUUID(string: "0000ffe1-0000-1000-8000-00805f9b34fb")
var ble_characteristic: CBCharacteristic?
var ble_perip: CBPeripheral?
class myBLERemoteUITests : XCTestCase {
var cbCentralManager : CBCentralManager!
func wait(timeout: TimeInterval){
let exp = expectation(description: "Wait for X seconds")
let result = XCTWaiter.wait(for: [exp], timeout: timeout)
print("LOG - Timer started for " + String(timeout) + " seconds...")
if result == XCTWaiter.Result.timedOut {
print("LOG - Timer stopped after " + String(timeout) + " seconds...")
}else {
XCTFail("Delay interrupted")
}
}
func test_someBLEtest() throws {
let app = XCUIApplication()
app.launch()
// MARK: Some UI automation steps
app.buttons["Get Started"].tap()
let tablesQuery2 = app.tables
let shoeImage = tablesQuery2.cells["ItemA"].images["item"]
shoeImage.tap()
let shoe2 = tablesQuery2.cells["ItemB"].images["item"]
shoe2.tap()
wait(timeout: 10)
app.buttons["Finish"].tap()
// MARK: Part where I need to communicate with BLE device
// Initialize CBCentralManager
cbCentralManager = CBCentralManager.init(delegate: self, queue: nil) // --> getting API MISUSE mentioned above
wait(timeout: 10)
cbCentralManager = CBCentralManager.init(delegate: self, queue: nil) // --> getting API MISUSE mentioned above
wait(timeout: 10)
cbCentralManager = CBCentralManager.init() // --> getting [CoreBluetooth] XPC connection invalid
// MARK: I check CBCentral Manager Authorization state
if (cbCentralManager.authorization == .allowedAlways){
print("allowed")
}else if (cbCentralManager.authorization == .notDetermined){
print("not determined") // --> I get that authorization is not determined
}
}
}
// MARK: Over here I have all needed CoreBluetooth callback functions:
extension myBLERemoteUITests : CBPeripheralDelegate {
func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) {
if let services = peripheral.services {
//discover characteristics of services
for service in services {
peripheral.discoverCharacteristics(nil, for: service)
}
}
}
func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
if let charac = service.characteristics {
for characteristic in charac {
peripheral.setNotifyValue(true, for: characteristic)
if characteristic.uuid == writeCharacteristic {
ble_characteristic = characteristic
}
for newChar: CBCharacteristic in service.characteristics!{
peripheral.readValue(for: newChar)
}
}
}
}
func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
if characteristic.uuid == readCharacteristic {
print("Read Value : \(characteristic)")
}
}
func peripheral(_ peripheral: CBPeripheral, didWriteValueFor characteristic: CBCharacteristic, error: Error?) {
if characteristic.uuid == writeCharacteristic {
print("WRITE VALUE : \(characteristic)")
}
}
}
extension myBLERemoteUITests : CBCentralManagerDelegate {
func centralManagerDidUpdateState(_ central: CBCentralManager) {
if central.state == .poweredOn {
central.scanForPeripherals(withServices: nil, options: nil)
print("Scanning...")
}
}
func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
guard peripheral.name != nil else {return}
if peripheral.name! == peripheralName {
print("BLE Device Found!")
//stopScan
cbCentralManager.stopScan()
//connect
cbCentralManager.connect(peripheral, options: nil)
ble_perip = peripheral
}
}
func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) {
print("Connected : \(peripheral.name ?? "No Name")")
peripheral.discoverServices([service_First])
//discover all service
//peripheral.discoverServices(nil)
peripheral.delegate = self
}
func centralManager(_ central: CBCentralManager, didDisconnectPeripheral peripheral: CBPeripheral, error: Error?) {
print("Disconnected : \(peripheral.name ?? "No Name")")
cbCentralManager.scanForPeripherals(withServices: nil, options: nil)
}
}