How to mock a CentralManager class

[gtatgh]

Is your feature request related to a problem? Please describe. I have a wrapper class BluetoothHandler around of CentralManager which configure the use of CentralManager, like in your example. So, how can I mock CentralManager in unit tests e.g. for scanning?

Describe the solution you'd like I would like to test the logic of BluetoothHandler.

class BluetoothHandlerTest: XCTestCase {
    func testStartScan() {
        let cm = CentralManager()
        let bh = BluetoothHandler(centralManager: cm)
        bh.startScan()
        // Here I want to inject mocked data
        cm.delegateWrapper.didDiscoverPeripheral(CBPeripheralMock(), nil, nil)
        XCTAssertEqual(1, bh.scannedPeripherals.count)
    }
}

Additional context

class BluetoothHandler {
    /**
     A list of scanned peripherals.
     */
    public let scannedPeripherals = [ScannedPeripheral]()

    ...

    init(centralManager: CentralManager) {
        self.centralManager = centralManager
    }

    func startScan() {
        scanningDisposable = centralManager
            .observeState()
            .startWith(centralManager.state)
            .filter {
                $0 == .poweredOn
            }
            .flatMap { _ -> Observable<ScannedPeripheral> in
                self.centralManager.scanForPeripherals(
                    withServices: nil,
                    options: nil)
            }.subscribe(
                onNext: { scannedPeripheral in
                    debugPrint("found a  new peripheral with name \(String(describing: scannedPeripheral.peripheral.name))")

                    scannedPeripherals.append(scannedPeripheral)
            })
    }
...
}

[minixT]

Hi @gtatgh Do you want to add tests to RxBluetoothKit library or to your project? If you want to use CentralManager mock in RxBluetoothKit tests you should use _CentralManager instead. This is autogenerated mock of CentalManager class. Example how it is used can be found in tests in the Tests folder. If you want to mock CentralManager in your own project you can create a protocol with methods which you want to use in your tests and use it instead CentralManager in your code. CentralManager should implement this protocol and you can also create a mock which also implements this protocol and use it in your tests.. If you are interested in more details please ask.

[gtatgh]

Hello @minixT, yes I want to mock CentralManager in my own project, specially in BluetoothHandler. I can create a protocol and extend it in BluetoothHandler. What I want is to receive e.g. ScannedPeripheral from CentralManager.

[JamesRoome]

@minixT I am about to do some testing and was looking into this... My question to you is: If it is the case that you recommend using a protocol for mocking, why does the main codebase not use that exact same approach? Peripheral could have been a protocol, but it isn't. Why?