public void CanExecuteChanged_UnsubscribeNonexistentEvent_DoesNothing()
{
var sender = new object();
object weakObservedSender = null;
object strongObservedSender = null;
object unsubscribedObservedSender = null;
var command = new WeakCanExecuteChanged(sender);
EventHandler weakSubscription = (s, _) =>
{
weakObservedSender = s;
};
EventHandler strongSubscription = (s, _) =>
{
strongObservedSender = s;
};
EventHandler unsubscribedSubscription = (s, _) =>
{
unsubscribedObservedSender = s;
};
command.CanExecuteChanged += strongSubscription;
command.CanExecuteChanged += weakSubscription;
weakSubscription = null;
GC.Collect();
command.CanExecuteChanged -= unsubscribedSubscription;
command.OnCanExecuteChanged();
Assert.Null(weakObservedSender);
Assert.Same(sender, strongObservedSender);
Assert.Null(unsubscribedObservedSender);
GC.KeepAlive(strongSubscription);
GC.KeepAlive(unsubscribedSubscription);
}
public void CanExecuteChanged_IsWeakEvent()
{
var sender = new object();
object weakObservedSender = null;
object strongObservedSender = null;
var command = new WeakCanExecuteChanged(sender);
EventHandler weakSubscription = (s, _) =>
{
weakObservedSender = s;
};
EventHandler strongSubscription = (s, _) =>
{
strongObservedSender = s;
};
command.CanExecuteChanged += weakSubscription;
command.CanExecuteChanged += strongSubscription;
weakSubscription = null;
GC.Collect();
command.OnCanExecuteChanged();
Assert.Null(weakObservedSender);
Assert.Same(sender, strongObservedSender);
GC.KeepAlive(strongSubscription);
}
public void CanExecuteChanged_Unsubscribed_IsNotNotified()
{
var sender = new object();
object observedSender = null;
var command = new WeakCanExecuteChanged(sender);
EventHandler subscription = (s, _) =>
{
observedSender = s;
};
command.CanExecuteChanged += subscription;
command.CanExecuteChanged -= subscription;
command.OnCanExecuteChanged();
Assert.Null(observedSender);
GC.KeepAlive(subscription);
}