From 699470d640ebbd58cb2173f2c6d38667f473414a Mon Sep 17 00:00:00 2001
From: William Chong <william-chong@outlook.com>
Date: Fri, 1 Nov 2024 20:52:15 +0400
Subject: [PATCH] Account for nullable events (#324)

* Account for nullable events

* Fix json vulnerability

* Upgrade deprecated gh actions

* Fix tests

* Remove susbcribe_to_stream test
---
 .../Diagnostics/ActivitySourceExtensions.cs   |  4 +-
 .../StreamsTracingInstrumentationTests.cs     | 47 +++++++++++++++++++
 .../Fixtures/DiagnosticsFixture.cs            |  2 +-
 3 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/src/EventStore.Client/Common/Diagnostics/ActivitySourceExtensions.cs b/src/EventStore.Client/Common/Diagnostics/ActivitySourceExtensions.cs
index 26bd00b44..28d336a85 100644
--- a/src/EventStore.Client/Common/Diagnostics/ActivitySourceExtensions.cs
+++ b/src/EventStore.Client/Common/Diagnostics/ActivitySourceExtensions.cs
@@ -1,3 +1,5 @@
+// ReSharper disable ConditionIsAlwaysTrueOrFalseAccordingToNullableAPIContract
+
 using System.Diagnostics;
 using EventStore.Diagnostics;
 using EventStore.Diagnostics.Telemetry;
@@ -32,7 +34,7 @@ public static void TraceSubscriptionEvent(
 		EventStoreClientSettings settings,
 		UserCredentials? userCredentials
 	) {
-		if (source.HasNoActiveListeners())
+		if (source.HasNoActiveListeners() || resolvedEvent.Event is null)
 			return;
 
 		var parentContext = resolvedEvent.Event.Metadata.ExtractPropagationContext();
diff --git a/test/EventStore.Client.Streams.Tests/Diagnostics/StreamsTracingInstrumentationTests.cs b/test/EventStore.Client.Streams.Tests/Diagnostics/StreamsTracingInstrumentationTests.cs
index 4c23bfffa..5a19c6b0d 100644
--- a/test/EventStore.Client.Streams.Tests/Diagnostics/StreamsTracingInstrumentationTests.cs
+++ b/test/EventStore.Client.Streams.Tests/Diagnostics/StreamsTracingInstrumentationTests.cs
@@ -1,3 +1,5 @@
+// ReSharper disable ConditionalAccessQualifierIsNonNullableAccordingToAPIContract
+
 using EventStore.Client.Diagnostics;
 using EventStore.Diagnostics.Tracing;
 
@@ -171,4 +173,49 @@ async Task Subscribe(IAsyncEnumerator<StreamMessage> internalEnumerator) {
 			}
 		}
 	}
+
+	[Fact]
+	[Trait("Category", "Special cases")]
+	public async Task should_not_trace_when_event_is_null() {
+		var category   = Guid.NewGuid().ToString("N");
+		var streamName = category + "-123";
+
+		var seedEvents = Fixture.CreateTestEvents(type: $"{category}-{Fixture.GetStreamName()}").ToArray();
+		await Fixture.Streams.AppendToStreamAsync(streamName, StreamState.NoStream, seedEvents);
+
+		await Fixture.Streams.DeleteAsync(streamName, StreamState.StreamExists);
+
+		await using var subscription = Fixture.Streams.SubscribeToStream("$ce-" + category, FromStream.Start, resolveLinkTos: true);
+
+		await using var enumerator = subscription.Messages.GetAsyncEnumerator();
+
+		Assert.True(await enumerator.MoveNextAsync());
+
+		Assert.IsType<StreamMessage.SubscriptionConfirmation>(enumerator.Current);
+
+		await Subscribe().WithTimeout();
+
+		var appendActivities = Fixture
+			.GetActivitiesForOperation(TracingConstants.Operations.Append, streamName)
+			.ShouldNotBeNull();
+
+		var subscribeActivities = Fixture
+			.GetActivitiesForOperation(TracingConstants.Operations.Subscribe, "$ce-" + category)
+			.ToArray();
+
+		appendActivities.ShouldHaveSingleItem();
+		subscribeActivities.ShouldBeEmpty();
+
+		return;
+
+		async Task Subscribe() {
+			while (await enumerator.MoveNextAsync()) {
+				if (enumerator.Current is not StreamMessage.Event(var resolvedEvent))
+					continue;
+
+				if (resolvedEvent.Event?.EventType is "$metadata")
+					return;
+			}
+		}
+	}
 }
diff --git a/test/EventStore.Client.Tests.Common/Fixtures/DiagnosticsFixture.cs b/test/EventStore.Client.Tests.Common/Fixtures/DiagnosticsFixture.cs
index f8cd5913b..549093654 100644
--- a/test/EventStore.Client.Tests.Common/Fixtures/DiagnosticsFixture.cs
+++ b/test/EventStore.Client.Tests.Common/Fixtures/DiagnosticsFixture.cs
@@ -11,7 +11,7 @@ namespace EventStore.Client.Tests;
 public class DiagnosticsFixture : EventStoreFixture {
 	readonly ConcurrentDictionary<(string Operation, string Stream), List<Activity>> _activities = [];
 
-	public DiagnosticsFixture() {
+	public DiagnosticsFixture() : base(x => x.RunProjections()) {
 		var diagnosticActivityListener = new ActivityListener {
 			ShouldListenTo = source => source.Name == EventStoreClientDiagnostics.InstrumentationName,
 			Sample = (ref ActivityCreationOptions<ActivityContext> _) => ActivitySamplingResult.AllDataAndRecorded,