fix: preserve original source for cloud event messages (#108)

--------- Co-authored-by: Gérald Barré <[email protected]> Co-authored-by: Dzhem Aptula <[email protected]> Co-authored-by: Dzhem Aptula <[email protected]>
workleap · Jan 28, 2025 · c62d954 · c62d954
1 parent 94b1bee
commit c62d954
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Showing 2 changed files with 44 additions and 8 deletions.
diff --git a/src/EventGridEmulator.Tests/EmulatorValidationTests.cs b/src/EventGridEmulator.Tests/EmulatorValidationTests.cs
@@ -15,7 +15,7 @@ public async Task ValidatePublishAndSubscribeRoundTripForEventGridEvent()
     {
         // Define the handler to intercept the message
         var message = string.Empty;
-        HttpMessageHandler handler = new TestHandler(requestAction => message = requestAction);
+        using HttpMessageHandler handler = new TestHandler(requestAction => message = requestAction);
 
         // Create the EventGrid subscriber
         using var subscriber = new FactoryClientBuilder(handler)
@@ -47,11 +47,11 @@ public async Task ValidatePublishAndSubscribeRoundTripForEventGridEvent()
     }
 
     [Fact]
-    public async Task ValidatePublishAndSubscribeRoundTripForCloudEvent()
+    public async Task ValidatePublishAndSubscribeRoundTripForCloudEventWithEmptySource()
     {
         // Define the handler to intercept the message
         var message = string.Empty;
-        HttpMessageHandler handler = new TestHandler(requestAction => message = requestAction);
+        using HttpMessageHandler handler = new TestHandler(requestAction => message = requestAction);
 
         // Create the EventGrid subscriber
         using var subscriber = new FactoryClientBuilder(handler)
@@ -63,8 +63,8 @@ public async Task ValidatePublishAndSubscribeRoundTripForCloudEvent()
             .WithEndpoint(new Uri("https://localhost/orders/api/events"))
             .Build();
 
-        // Create and send an event to EventGrid
-        var cloudEvent = new CloudEvent("foo", "bar", new DataModel(some: "data"));
+        // Create and send an event to EventGrid with an empty source
+        var cloudEvent = new CloudEvent("", "bar", new DataModel(some: "data"));
         var response = await publisher.SendEventAsync(cloudEvent);
 
         // Assert that the message was successfully sent
@@ -73,9 +73,42 @@ public async Task ValidatePublishAndSubscribeRoundTripForCloudEvent()
         // Assert that the message was successfully received
         var @event = JsonSerializer.Deserialize<JsonObject[]>(message) ?? throw new NullReferenceException("Message cannot be deserialized");
         var result = @event.Single()["data"].Deserialize<DataModel>();
-        var receivedTopic = @event.Single()["source"].Deserialize<string>();
+        var receivedSource = @event.Single()["source"].Deserialize<string>();
         Assert.Equal("data", result?.Some);
-        Assert.Equal($"{SubscriberConstants.DefaultTopicValue}{ExpectedTopic}", receivedTopic);
+        Assert.Equal($"{SubscriberConstants.DefaultTopicValue}{ExpectedTopic}", receivedSource);
+    }
+
+    [Fact]
+    public async Task ValidatePublishAndSubscribeRoundTripForCloudEventPreserveOriginalSource()
+    {
+        // Define the handler to intercept the message
+        var message = string.Empty;
+        var originalSource = "SOME_SOURCE_VALUE";
+        using HttpMessageHandler handler = new TestHandler(requestAction => message = requestAction);
+
+        // Create the EventGrid subscriber
+        using var subscriber = new FactoryClientBuilder(handler)
+            .WithTopic(ExpectedTopic, "https://localhost/orders-webhook")
+            .Build();
+
+        // Create the EventGrid publisher
+        var publisher = new PublisherBuilder(subscriber)
+            .WithEndpoint(new Uri("https://localhost/orders/api/events"))
+            .Build();
+
+        // Create and send an event to EventGrid with a source
+        var cloudEvent = new CloudEvent(originalSource, "bar", new DataModel(some: "data"));
+        var response = await publisher.SendEventAsync(cloudEvent);
+
+        // Assert that the message was successfully sent
+        Assert.Equal(200, response.Status);
+
+        // Assert that the message was successfully received
+        var @event = JsonSerializer.Deserialize<JsonObject[]>(message) ?? throw new NullReferenceException("Message cannot be deserialized");
+        var result = @event.Single()["data"].Deserialize<DataModel>();
+        var receivedSource = @event.Single()["source"].Deserialize<string>();
+        Assert.Equal("data", result?.Some);
+        Assert.Equal(originalSource, receivedSource);
     }
 
     private sealed class DataModel

diff --git a/src/EventGridEmulator/EventHandling/CloudEventHttpContextHandler.cs b/src/EventGridEmulator/EventHandling/CloudEventHttpContextHandler.cs
@@ -21,7 +21,10 @@ protected override void EnhanceEventData(IEnumerable<CloudEvent> cloudEvents, st
     {
         foreach (var @event in cloudEvents)
         {
-            @event.Source = $"{SubscriberConstants.DefaultTopicValue}{topicName}";
+            if (string.IsNullOrEmpty(@event.Source))
+            {
+                @event.Source = $"{SubscriberConstants.DefaultTopicValue}{topicName}";
+            }
         }
     }
 }