Add tests and docs for publishing CloudEvent to domain topics (Azure#25511)

* Add tests and docs for publishing CloudEvent to domain topics.

* PR fb

* Fix snippets

Author: JoshLove-msft

sdk/eventgrid/Azure.Messaging.EventGrid/README.md

@@ -228,6 +228,27 @@ List<EventGridEvent> eventsList = new List<EventGridEvent>
 await client.SendEventsAsync(eventsList);
 ```
 
+For sending CloudEvents, the CloudEvent source is used as the domain topic:
+```C# Snippet:SendCloudEventsToDomain
+List<CloudEvent> eventsList = new List<CloudEvent>();
+
+for (int i = 0; i < 10; i++)
+{
+    CloudEvent cloudEvent = new CloudEvent(
+        // the source is mapped to the domain topic
+        $"Subject-{i}",
+        "Microsoft.MockPublisher.TestEvent",
+        "hello")
+    {
+        Id = $"event-{i}",
+        Time = DateTimeOffset.Now
+    };
+    eventsList.Add(cloudEvent);
+}
+
+await client.SendEventsAsync(eventsList);
+```
+
 ### Receiving and Deserializing Events
 There are several different Azure services that act as [event handlers](https://docs.microsoft.com/azure/event-grid/event-handlers).
 

sdk/eventgrid/Azure.Messaging.EventGrid/tests/EventGridClientLiveTests.cs

@@ -209,6 +209,42 @@ public async Task CanPublishEventToDomain()
             await client.SendEventsAsync(eventsList);
         }
 
+        [RecordedTest]
+        public async Task CanPublishCloudEventToDomain()
+        {
+            EventGridPublisherClientOptions options = InstrumentClientOptions(new EventGridPublisherClientOptions());
+            EventGridPublisherClient client = InstrumentClient(
+                new EventGridPublisherClient(
+                    new Uri(TestEnvironment.CloudEventDomainHost),
+                    new AzureKeyCredential(TestEnvironment.CloudEventDomainKey),
+                    options));
+
+            #region Snippet:SendCloudEventsToDomain
+            List<CloudEvent> eventsList = new List<CloudEvent>();
+
+            for (int i = 0; i < 10; i++)
+            {
+                CloudEvent cloudEvent = new CloudEvent(
+                    // the source is mapped to the domain topic
+                    $"Subject-{i}",
+                    "Microsoft.MockPublisher.TestEvent",
+                    "hello")
+                {
+#if SNIPPET
+                    Id = $"event-{i}",
+                    Time = DateTimeOffset.Now
+#else
+                    Id = Recording.Random.NewGuid().ToString(),
+                    Time = Recording.Now
+#endif
+                };
+                eventsList.Add(cloudEvent);
+            }
+
+            await client.SendEventsAsync(eventsList);
+            #endregion
+        }
+
         [RecordedTest]
         public async Task CanPublishEventToDomainAAD()
         {

sdk/eventgrid/Azure.Messaging.EventGrid/tests/Infrastructure/EventGridTestEnvironment.cs

@@ -14,6 +14,9 @@ public class EventGridTestEnvironment : TestEnvironment
         public const string DomainKeyEnvironmentVariableName = "EVENT_GRID_DOMAIN_KEY";
         public const string DomainEndpointEnvironmentVariableName = "EVENT_GRID_DOMAIN_ENDPOINT";
 
+        public const string CloudEventDomainKeyEnvironmentVariableName = "EVENT_GRID_CLOUD_EVENT_DOMAIN_KEY";
+        public const string CloudEventDomainEndpointEnvironmentVariableName = "EVENT_GRID_CLOUD_EVENT_DOMAIN_ENDPOINT";
+
         public const string CloudEventTopicKeyEnvironmentVariableName = "EVENT_GRID_CLOUD_EVENT_TOPIC_KEY";
         public const string CloudEventTopicEndpointEnvironmentVariableName = "EVENT_GRID_CLOUD_EVENT_TOPIC_ENDPOINT";
 
@@ -26,6 +29,9 @@ public class EventGridTestEnvironment : TestEnvironment
         public string DomainHost => GetRecordedVariable(DomainEndpointEnvironmentVariableName);
         public string DomainKey => GetRecordedVariable(DomainKeyEnvironmentVariableName, options => options.IsSecret(SanitizedValue.Base64));
 
+        public string CloudEventDomainHost => GetRecordedVariable(CloudEventDomainEndpointEnvironmentVariableName);
+        public string CloudEventDomainKey => GetRecordedVariable(CloudEventDomainKeyEnvironmentVariableName, options => options.IsSecret(SanitizedValue.Base64));
+
         public string CloudEventTopicHost => GetRecordedVariable(CloudEventTopicEndpointEnvironmentVariableName);
         public string CloudEventTopicKey => GetRecordedVariable(CloudEventTopicKeyEnvironmentVariableName, options => options.IsSecret(SanitizedValue.Base64));
 

sdk/eventgrid/Azure.Messaging.EventGrid/tests/SessionRecords/EventGridClientLiveTests/CanPublishCloudEventToDomain.json

@@ -48,6 +48,7 @@ For detailed information about the Event Grid client library concepts: [Event Gr
 
 ## Examples
 
+### Publish to an Event Grid topic
 ```C# Snippet:CloudNativePublish
 EventGridPublisherClient client = new EventGridPublisherClient(
         new Uri(TestEnvironment.CloudEventTopicHost),
@@ -64,6 +65,23 @@ var cloudEvent =
 await client.SendCloudNativeCloudEventAsync(cloudEvent);
 ```
 
+### Publish to an Event Grid Domain
+When publishing to an Event Grid Domain with CloudEvents, the CloudEvent `source` is used as the domain topic. The Event Grid service doesn't support using an absolute URI for a domain topic, so you would need to do something like the following to integrate with the CloudNative CloudEvents:
+```C# Snippet:CloudNativePublishToDomain
+CloudEvent cloudEvent =
+    new CloudEvent
+    {
+        Type = "record",
+        // Event Grid does not allow absolute URIs as the domain topic
+        Source = new Uri("test", UriKind.Relative),
+        Id = "eventId",
+        Time = DateTimeOffset.Now,
+        Data = new TestPayload("name", 0)
+    };
+
+await client.SendCloudNativeCloudEventAsync(cloudEvent);
+```
+
 ## Troubleshooting
 
 For troubleshooting information, see the [Event Grid Client Library documentation](https://github.com/Azure/azure-sdk-for-net/tree/main/sdk/eventgrid/Azure.Messaging.EventGrid#troubleshooting).

sdk/eventgrid/Azure.Messaging.EventGrid/tests/SessionRecords/EventGridClientLiveTests/CanPublishCloudEventToDomainAsync.json

@@ -70,6 +70,37 @@ public async Task CanPublishSingleCloudEvent()
             await client.SendCloudNativeCloudEventAsync(cloudEvent);
         }
 
+        [RecordedTest]
+        public async Task CanPublishCloudEventToDomain()
+        {
+            EventGridPublisherClientOptions options = InstrumentClientOptions(new EventGridPublisherClientOptions());
+            EventGridPublisherClient client = InstrumentClient(
+                new EventGridPublisherClient(
+                    new Uri(TestEnvironment.CloudEventDomainHost),
+                    new AzureKeyCredential(TestEnvironment.CloudEventDomainKey),
+                    options));
+
+            #region Snippet:CloudNativePublishToDomain
+            CloudEvent cloudEvent =
+                new CloudEvent
+                {
+                    Type = "record",
+                    // Event Grid does not allow absolute URIs as the domain topic
+                    Source = new Uri("test", UriKind.Relative),
+#if SNIPPET
+                    Id = "eventId",
+                    Time = DateTimeOffset.Now,
+#else
+                    Id = Recording.Random.NewGuid().ToString(),
+                    Time = Recording.Now,
+#endif
+                    Data = new TestPayload("name", 0)
+                };
+
+            await client.SendCloudNativeCloudEventAsync(cloudEvent);
+            #endregion
+        }
+
         private class TestPayload
         {
             public TestPayload(string name, int age)