Merge pull request #2034 from thomaslevesque/fix-null-event-handler

Fix event subscription/unsubscription with null handler
FakeItEasy · Jun 19, 2024 · 94caef0 · 94caef0
2 parents 87511a7 + bc16732
commit 94caef0
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Showing 2 changed files with 34 additions and 2 deletions.
diff --git a/src/FakeItEasy/Core/EventCall.cs b/src/FakeItEasy/Core/EventCall.cs
@@ -34,7 +34,13 @@ public static bool TryGetEventCall(IFakeObjectCall fakeObjectCall, [NotNullWhen(
                 return false;
             }
 
-            eventCall = new EventCall(eventInfo, fakeObjectCall.Method, (Delegate)fakeObjectCall.Arguments[0]!);
+            var handler = fakeObjectCall.Arguments.Get<Delegate>(0);
+            if (handler is null)
+            {
+                return false;
+            }
+
+            eventCall = new EventCall(eventInfo, fakeObjectCall.Method, handler);
             return true;
         }
 

diff --git a/tests/FakeItEasy.Specs/EventRaisingSpecs.cs → tests/FakeItEasy.Specs/EventSpecs.cs b/tests/FakeItEasy.Specs/EventRaisingSpecs.cs → tests/FakeItEasy.Specs/EventSpecs.cs
@@ -27,7 +27,7 @@ public class DerivedReferenceType : ReferenceType
     {
     }
 
-    public class EventRaisingSpecs
+    public class EventSpecs
     {
         private readonly EventArgs eventArgs = new EventArgs();
 
@@ -526,5 +526,31 @@ public void RaisingInternalEvent(ClassWithInternalEventVisibleToDynamicProxy fak
             "Then the handler is called"
                 .x(() => A.CallTo(handler).MustHaveHappened());
         }
+
+        [Scenario]
+        public void SubscribeWithNullHandler(IEvents fake, Exception? exception)
+        {
+            "Given a fake with an event"
+                .x(() => fake = A.Fake<IEvents>());
+
+            "When subscribing to the event with a null handler"
+                .x(() => exception = Record.Exception(() => fake.UnsubscribedEvent += null));
+
+            "Then it should not throw"
+                .x(() => exception.Should().BeNull());
+        }
+
+        [Scenario]
+        public void UnsubscribeWithNullHandler(IEvents fake, Exception? exception)
+        {
+            "Given a fake with an event"
+                .x(() => fake = A.Fake<IEvents>());
+
+            "When unsubscribing from the event with a null handler"
+                .x(() => exception = Record.Exception(() => fake.UnsubscribedEvent -= null));
+
+            "Then it should not throw"
+                .x(() => exception.Should().BeNull());
+        }
     }
 }