diff --git a/tests/Client/ZB.MOM.WW.OtOpcUa.Client.UI.Tests/Fakes/FakeOpcUaClientService.cs b/tests/Client/ZB.MOM.WW.OtOpcUa.Client.UI.Tests/Fakes/FakeOpcUaClientService.cs
index e8cbbdbb..d1fef1a9 100644
--- a/tests/Client/ZB.MOM.WW.OtOpcUa.Client.UI.Tests/Fakes/FakeOpcUaClientService.cs
+++ b/tests/Client/ZB.MOM.WW.OtOpcUa.Client.UI.Tests/Fakes/FakeOpcUaClientService.cs
@@ -265,21 +265,39 @@ public sealed class FakeOpcUaClientService : IOpcUaClientService
 
     /// <summary>Gets or sets the status code returned by confirmation operations in UI tests.</summary>
     public StatusCode ConfirmResult { get; set; } = StatusCodes.Good;
+    /// <summary>Gets or sets the exception thrown to simulate alarm confirmation failures in the UI.</summary>
+    public Exception? ConfirmException { get; set; }
+    /// <summary>Gets the number of times ConfirmAlarmAsync has been called.</summary>
+    public int ConfirmCallCount { get; private set; }
+    /// <summary>Gets the (conditionNodeId, eventId, comment) of the last ConfirmAlarmAsync call.</summary>
+    public (string ConditionNodeId, byte[] EventId, string Comment)? LastConfirmCall { get; private set; }
 
     /// <inheritdoc />
     public Task<StatusCode> ConfirmAlarmAsync(string conditionNodeId, byte[] eventId, string comment,
         CancellationToken ct = default)
     {
+        ConfirmCallCount++;
+        LastConfirmCall = (conditionNodeId, eventId, comment);
+        if (ConfirmException != null) throw ConfirmException;
         return Task.FromResult(ConfirmResult);
     }
 
     /// <summary>Gets or sets the status code returned by shelve operations in UI tests.</summary>
     public StatusCode ShelveResult { get; set; } = StatusCodes.Good;
+    /// <summary>Gets or sets the exception thrown to simulate alarm shelve failures in the UI.</summary>
+    public Exception? ShelveException { get; set; }
+    /// <summary>Gets the number of times ShelveAlarmAsync has been called.</summary>
+    public int ShelveCallCount { get; private set; }
+    /// <summary>Gets the (conditionNodeId, kind, shelvingTimeSeconds) of the last ShelveAlarmAsync call.</summary>
+    public (string ConditionNodeId, ShelveKind Kind, double ShelvingTimeSeconds)? LastShelveCall { get; private set; }
 
     /// <inheritdoc />
     public Task<StatusCode> ShelveAlarmAsync(string conditionNodeId, ShelveKind kind, double shelvingTimeSeconds = 0,
         CancellationToken ct = default)
     {
+        ShelveCallCount++;
+        LastShelveCall = (conditionNodeId, kind, shelvingTimeSeconds);
+        if (ShelveException != null) throw ShelveException;
         return Task.FromResult(ShelveResult);
     }