public void Test_MemoryLeak_WeakEvent()
{
// 1. Normal Event will hold the strong reference which prevent the GC collect.
var view = new TestView();
var viewModel = new TestViewModel();
var reference = new WeakReference(view);
viewModel.TestViewModelEvent += view.OnEventOccured;
viewModel.RaiseTestViewModelEvent();
Assert.AreEqual(1, view.EventCount);
Assert.AreEqual(1, viewModel.GetTestViewModelEventInvocationCount());
view = null;
GC.Collect();
Assert.IsTrue(reference.IsAlive); // Still live
viewModel.TestViewModelEvent -= reference.GetTarget<TestView>().OnEventOccured;
GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();
Assert.IsFalse(reference.IsAlive);
reference = null;
Assert.IsNull(reference.GetTarget<TestView>());
// 2. WeakEvent hold the weak reference which will not prevent GC collect.
var view2 = new TestView();
var viewModel2 = new TestViewModel();
var reference2 = new WeakReference(view2);
var weakEvent = new WeakEvent(view2);
weakEvent.AttachEvent(viewModel2, null, "TestViewModelEvent", "OnEventOccured");
viewModel2.RaiseTestViewModelEvent();
Assert.AreEqual(1, view2.EventCount);
view2 = null;
GC.Collect();
Assert.IsFalse(reference2.IsAlive);
viewModel2.RaiseTestViewModelEvent();
Assert.AreEqual(0, viewModel2.GetTestViewModelEventInvocationCount());
}
