Add strongly-typed SendEvent methods for DurableEventAttribute

- Added AddEventSendMethod to generate Send{EventName} extension methods
- Generated methods provide type-safe way to send events between orchestrations
- Updated all 3 event unit tests to verify SendEvent generation
- All 41 generator tests passing
- AzureFunctionsApp builds successfully with new methods

Co-authored-by: YunchuWang <[email protected]>

Author: Copilot

src/Generators/DurableTaskSourceGenerator.cs

@@ -344,6 +344,7 @@ public static class GeneratedDurableTaskExtensions
             foreach (DurableEventTypeInfo eventInfo in allEvents)
             {
                 AddEventWaitMethod(sourceBuilder, eventInfo);
+                AddEventSendMethod(sourceBuilder, eventInfo);
             }
 
             if (isDurableFunctions)
@@ -452,6 +453,19 @@ static void AddEventWaitMethod(StringBuilder sourceBuilder, DurableEventTypeInfo
         }}");
         }
 
+        static void AddEventSendMethod(StringBuilder sourceBuilder, DurableEventTypeInfo eventInfo)
+        {
+            sourceBuilder.AppendLine($@"
+        /// <summary>
+        /// Sends an external event of type <see cref=""{eventInfo.TypeName}""/> to another orchestration instance.
+        /// </summary>
+        /// <inheritdoc cref=""TaskOrchestrationContext.SendEvent(string, string, object)""/>
+        public static void Send{eventInfo.EventName}(this TaskOrchestrationContext context, string instanceId, {eventInfo.TypeName} eventData)
+        {{
+            context.SendEvent(instanceId, ""{eventInfo.EventName}"", eventData);
+        }}");
+        }
+
         static void AddActivityFunctionDeclaration(StringBuilder sourceBuilder, DurableTaskTypeInfo activity)
         {
             // GeneratedActivityContext is a generated class that we use for each generated activity trigger definition.

test/Generators.Tests/ClassBasedSyntaxTests.cs

@@ -533,6 +533,15 @@ public sealed record ApprovalEvent(bool Approved, string? Approver);";
 public static Task<ApprovalEvent> WaitForApprovalEventAsync(this TaskOrchestrationContext context, CancellationToken cancellationToken = default)
 {
     return context.WaitForExternalEvent<ApprovalEvent>(""ApprovalEvent"", cancellationToken);
+}
+
+/// <summary>
+/// Sends an external event of type <see cref=""ApprovalEvent""/> to another orchestration instance.
+/// </summary>
+/// <inheritdoc cref=""TaskOrchestrationContext.SendEvent(string, string, object)""/>
+public static void SendApprovalEvent(this TaskOrchestrationContext context, string instanceId, ApprovalEvent eventData)
+{
+    context.SendEvent(instanceId, ""ApprovalEvent"", eventData);
 }");
 
         return TestHelpers.RunTestAsync<DurableTaskSourceGenerator>(
@@ -565,6 +574,15 @@ public class MyEventData
 public static Task<MyEventData> WaitForCustomEventNameAsync(this TaskOrchestrationContext context, CancellationToken cancellationToken = default)
 {
     return context.WaitForExternalEvent<MyEventData>(""CustomEventName"", cancellationToken);
+}
+
+/// <summary>
+/// Sends an external event of type <see cref=""MyEventData""/> to another orchestration instance.
+/// </summary>
+/// <inheritdoc cref=""TaskOrchestrationContext.SendEvent(string, string, object)""/>
+public static void SendCustomEventName(this TaskOrchestrationContext context, string instanceId, MyEventData eventData)
+{
+    context.SendEvent(instanceId, ""CustomEventName"", eventData);
 }");
 
         return TestHelpers.RunTestAsync<DurableTaskSourceGenerator>(
@@ -598,6 +616,15 @@ public record DataReceivedEvent(int Id, string Data);
 public static Task<MyNS.DataReceivedEvent> WaitForDataReceivedEventAsync(this TaskOrchestrationContext context, CancellationToken cancellationToken = default)
 {
     return context.WaitForExternalEvent<MyNS.DataReceivedEvent>(""DataReceivedEvent"", cancellationToken);
+}
+
+/// <summary>
+/// Sends an external event of type <see cref=""MyNS.DataReceivedEvent""/> to another orchestration instance.
+/// </summary>
+/// <inheritdoc cref=""TaskOrchestrationContext.SendEvent(string, string, object)""/>
+public static void SendDataReceivedEvent(this TaskOrchestrationContext context, string instanceId, MyNS.DataReceivedEvent eventData)
+{
+    context.SendEvent(instanceId, ""DataReceivedEvent"", eventData);
 }");
 
         return TestHelpers.RunTestAsync<DurableTaskSourceGenerator>(