From 1030a20fac73e5e9f641ed81e016b80a1a9bd36d Mon Sep 17 00:00:00 2001
From: Stefan Steinhilber <stefan.steinhilber@bizerba.com>
Date: Mon, 21 Jun 2021 11:32:38 +0200
Subject: [PATCH] Fix register/unregister issues of WeakReferenceMessenger
---
.../Messaging/WeakReferenceMessenger.cs | 4 +++-
.../UnitTests.Shared/Mvvm/Test_Messenger.cs | 23 +++++++++++++++++++
2 files changed, 26 insertions(+), 1 deletion(-)
diff --git a/Microsoft.Toolkit.Mvvm/Messaging/WeakReferenceMessenger.cs b/Microsoft.Toolkit.Mvvm/Messaging/WeakReferenceMessenger.cs
index 3f79f23..19e1449 100644
--- a/Microsoft.Toolkit.Mvvm/Messaging/WeakReferenceMessenger.cs
+++ b/Microsoft.Toolkit.Mvvm/Messaging/WeakReferenceMessenger.cs
@@ -406,6 +406,8 @@ public bool MoveNext()
while (node is not null)
{
+ LinkedListNode<WeakReference<TKey>>? nextNode = node.Next;
+
// Get the key and value for the current node
if (node.Value.TryGetTarget(out TKey? target) &&
this.owner.table.TryGetValue(target!, out TValue? value))
@@ -421,7 +423,7 @@ public bool MoveNext()
this.owner.keys.Remove(node);
}
- node = node.Next;
+ node = nextNode;
}
return false;
diff --git a/UnitTests/UnitTests.Shared/Mvvm/Test_Messenger.cs b/UnitTests/UnitTests.Shared/Mvvm/Test_Messenger.cs
index e5b4fd0..6b9009e 100644
--- a/UnitTests/UnitTests.Shared/Mvvm/Test_Messenger.cs
+++ b/UnitTests/UnitTests.Shared/Mvvm/Test_Messenger.cs
@@ -511,6 +511,29 @@ void Test()
messenger.Cleanup();
}
+ [TestCategory("Mvvm")]
+ [TestMethod]
+ [DataRow(typeof(StrongReferenceMessenger))]
+ [DataRow(typeof(WeakReferenceMessenger))]
+ public void Test_Messenger_RegisterMultiple_UnregisterSingle(Type type)
+ {
+ var messenger = (IMessenger)Activator.CreateInstance(type);
+
+ var recipient1 = new object();
+ var recipient2 = new object();
+
+ int handlerCalledCount = 0;
+
+ messenger.Register<object, MessageA>(recipient1, (r, m) => { handlerCalledCount++; });
+ messenger.Register<object, MessageA>(recipient2, (r, m) => { handlerCalledCount++; });
+
+ messenger.UnregisterAll(recipient2);
+
+ messenger.Send(new MessageA());
+
+ Assert.AreEqual(1, handlerCalledCount);
+ }
+
public sealed class RecipientWithNoMessages
{
public int Number { get; set; }