There are a few things you might be missing:
You are using NSUserNotification which is deprecated in macOS 10.14 and later. You should use NSUserNotificationCenter instead.

You are trying to use NSUserNotificationCenter with NSUserNotification which is not correct.

NSUserNotificationCenter is used to display notifications, and NSUserNotification is used to create the content of the notification.

Here is the correct way to do it:

let notification = NSUserNotification()
notification.title = "test"
notification.subtitle = "Test notification"
notification.informativeText = "this the test notification"
NSUserNotificationCenter.default.deliver(notification)

This will not work because NSUserNotificationCenter does not support delivering notifications directly. You need to schedule the notification to be delivered at a later time.

Here is how you can do it:

let notification = NSUserNotification()
notification.title = "test"
notification.subtitle = "Test notification"
notification.informativeText = "this the test notification"

let notificationCenter = NSUserNotificationCenter.default
notificationCenter.deliveryAlert = true
notificationCenter.schedule(notification)

This will schedule the notification to be delivered. However, this will not work if the user has not granted permission to your app to display notifications. You need to request permission first:

let center = UNUserNotificationCenter.current()
center.requestAuthorization(options: [.alert, .sound, .badge]) { allowed, error in
    if allowed {
        print("Notifications allowed")
    } else {
        print("Notifications denied")
    }
}

This will request permission to display notifications. If the user grants permission, you can schedule the notification to be delivered.

Remember to handle the case where the user denies permission. In this case, you should not schedule the notification.

Also, remember to handle the case where the user has granted permission but has not allowed notifications to be displayed in the notification center. In this case, you should not schedule the notification.

For macOS version 10.14 and above please use UNUserNotificationCenter instead of NSUserNotification

For delegate on macOS 10.14 and above

@available(macOS 10.14, *)
public func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
    completionHandler([.sound, .alert])
}

For delegate on macOS lower than 10.14

public func userNotificationCenter(_ center: NSUserNotificationCenter, shouldPresent notification: NSUserNotification) -> Bool {
    return true
}

For triggering the notification on macOS 10.14 and above

let content: UNMutableNotificationContent = UNMutableNotificationContent()
content.title = "test"
content.body = "Test notification"
let request = UNNotificationRequest(identifier: "Test Identifier", content: content, trigger: nil)
UNUserNotificationCenter.current().delegate = self
UNUserNotificationCenter.current().add(request, withCompletionHandler: nil)

For triggering the notification on macOS lower than 10.14

let notification = NSUserNotification()
notification.title = "test"
notification.informativeText = "Test notification"
notification.soundName = NSUserNotificationDefaultSoundName
delegate = self
deliver(notification)

Your permission code is correct.