mock AVCaptureDevice in Xcode 9

MockAVCaptureDevice.swift

extension AVCaptureDevice {
    class func swizzle() {
        [(#selector(AVCaptureDevice.defaultDevice(withMediaType:)), #selector(AVCaptureDevice.mockDefaultDevice(withMediaType:)))].forEach {
            let original = class_getClassMethod(self, $0)
            let mock = class_getClassMethod(self, $1)
            method_exchangeImplementations(original, mock)
        }
        [(#selector(AVCaptureDevice.hasMediaType(_:)), #selector(AVCaptureDevice.mockHasMediaType(_:))),
         (#selector(AVCaptureDevice.supportsAVCaptureSessionPreset(_:)), #selector(AVCaptureDevice.mockSupportsAVCaptureSessionPreset)),
         (#selector(AVCaptureDevice.isTorchModeSupported(_:)), #selector(AVCaptureDevice.mockIsTorchModeSupported)),
         (#selector(getter: AVCaptureDevice.torchMode), #selector(getter: AVCaptureDevice.mockTorchMode)),
         (#selector(setter: AVCaptureDevice.torchMode), #selector(setter: AVCaptureDevice.mockTorchMode))].forEach {
            let original = class_getInstanceMethod(self, $0)
            let mock = class_getInstanceMethod(self, $1)
            method_exchangeImplementations(original, mock)
        }
        [(#selector(AVCaptureDevice.init(mock:)), #selector(NSObject.init))].forEach {
            let original = class_getInstanceMethod(self, $0)
            let mock = class_getInstanceMethod(self, $1)
            method_setImplementation(original, method_getImplementation(mock))
        }
    }

    @objc convenience init(mock: String) {
        fatalError("should never be called because this is fake method replaced by original init")
    }

    class func mockDefaultDevice(withMediaType type: String) -> AVCaptureDevice? {
        return AVCaptureDevice(mock: "")
    }


    func mockHasMediaType(_ mediaType: String!) -> Bool {
        return true
    }

    func mockSupportsAVCaptureSessionPreset(_ preset: String!) -> Bool {
        return true
    }

    func mockIsTorchModeSupported(_ torchMode: AVCaptureTorchMode) -> Bool {
        return UI_USER_INTERFACE_IDIOM() != .pad
    }

    var mockTorchMode: AVCaptureTorchMode {
        get {return .off}
        set {}
    }
}