.NET: Make sure Workflow activities are as expected (#1903)

* Make sure Workflow activities are as expected

* misc

* Copliot comments

* Fix unit tests

* Improve test stability

* Fix unit tests

* Fix formatting

dotnet/src/Microsoft.Agents.AI.Workflows/Execution/StreamingRunEventStream.cs

@@ -2,10 +2,12 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using System.Threading;
 using System.Threading.Channels;
 using System.Threading.Tasks;
+using Microsoft.Agents.AI.Workflows.Observability;
 
 namespace Microsoft.Agents.AI.Workflows.Execution;
 
@@ -15,6 +17,9 @@ namespace Microsoft.Agents.AI.Workflows.Execution;
 /// </summary>
 internal sealed class StreamingRunEventStream : IRunEventStream
 {
+    private static readonly string s_namespace = typeof(StreamingRunEventStream).Namespace!;
+    private static readonly ActivitySource s_activitySource = new(s_namespace);
+
     private readonly Channel<WorkflowEvent> _eventChannel;
     private readonly ISuperStepRunner _stepRunner;
     private readonly InputWaiter _inputWaiter;
@@ -58,6 +63,9 @@ internal sealed class StreamingRunEventStream : IRunEventStream
         // Subscribe to events - they will flow directly to the channel as they're raised
         this._stepRunner.OutgoingEvents.EventRaised += OnEventRaisedAsync;
 
+        using Activity? activity = s_activitySource.StartActivity(ActivityNames.WorkflowRun);
+        activity?.SetTag(Tags.WorkflowId, this._stepRunner.StartExecutorId).SetTag(Tags.RunId, this._stepRunner.RunId);
+
         try
         {
             // Wait for the first input before starting
@@ -65,6 +73,7 @@ internal sealed class StreamingRunEventStream : IRunEventStream
             await this._inputWaiter.WaitForInputAsync(cancellationToken: linkedSource.Token).ConfigureAwait(false);
 
             this._runStatus = RunStatus.Running;
+            activity?.AddEvent(new ActivityEvent(EventNames.WorkflowStarted));
 
             while (!linkedSource.Token.IsCancellationRequested)
             {
@@ -99,9 +108,17 @@ internal sealed class StreamingRunEventStream : IRunEventStream
         {
             // Expected during shutdown
         }
-        catch (Exception e)
+        catch (Exception ex)
         {
-            await this._eventChannel.Writer.WriteAsync(new WorkflowErrorEvent(e), linkedSource.Token).ConfigureAwait(false);
+            if (activity != null)
+            {
+                activity.AddEvent(new ActivityEvent(EventNames.WorkflowError, tags: new() {
+                             { Tags.ErrorType, ex.GetType().FullName },
+                             { Tags.BuildErrorMessage, ex.Message },
+                        }));
+                activity.CaptureException(ex);
+            }
+            await this._eventChannel.Writer.WriteAsync(new WorkflowErrorEvent(ex), linkedSource.Token).ConfigureAwait(false);
         }
         finally
         {
@@ -110,6 +127,7 @@ internal sealed class StreamingRunEventStream : IRunEventStream
 
             // Mark as ended when run loop exits
             this._runStatus = RunStatus.Ended;
+            activity?.AddEvent(new ActivityEvent(EventNames.WorkflowCompleted));
         }
 
         async ValueTask OnEventRaisedAsync(object? sender, WorkflowEvent e)

dotnet/tests/Microsoft.Agents.AI.Workflows.UnitTests/ObservabilityTests.cs

@@ -0,0 +1,186 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Threading.Tasks;
+using FluentAssertions;
+using Microsoft.Agents.AI.Workflows.InProc;
+using Microsoft.Agents.AI.Workflows.Observability;
+
+namespace Microsoft.Agents.AI.Workflows.UnitTests;
+
+/// <summary>
+/// These tests ensure that OpenTelemetry Activity traces are properly created for workflow monitoring.
+/// Tests are run in a collection to avoid parallel execution since ActivityListener is global.
+/// Each test creates a new instance of ObservabilityTests and runs in serial within the collection.
+/// This prevents interference between tests due to the global nature of ActivityListener.
+/// </summary>
+[Collection("ObservabilityTests")]
+public sealed class ObservabilityTests : IDisposable
+{
+    private readonly ActivityListener _activityListener;
+    private readonly ConcurrentBag<Activity> _capturedActivities = [];
+
+    private bool _isDisposed;
+
+    public ObservabilityTests()
+    {
+        // Set up activity listener to capture activities from workflow
+        // This is global and captures ALL workflow activities from ANY test in the same process!
+        this._activityListener = new ActivityListener
+        {
+            ShouldListenTo = source => source.Name.Contains(typeof(Workflow).Namespace!),
+            Sample = (ref ActivityCreationOptions<ActivityContext> options) => ActivitySamplingResult.AllData,
+            ActivityStarted = activity => this._capturedActivities.Add(activity),
+        };
+        ActivitySource.AddActivityListener(this._activityListener);
+    }
+
+    /// <summary>
+    /// Create a sample workflow for testing.
+    /// </summary>
+    /// <remarks>
+    /// This workflow is expected to create 8 activities that will be captured by the tests
+    /// - ActivityNames.WorkflowBuild
+    /// - ActivityNames.WorkflowRun
+    /// -- ActivityNames.EdgeGroupProcess
+    /// -- ActivityNames.ExecutorProcess (UppercaseExecutor)
+    /// --- ActivityNames.MessageSend
+    /// ---- ActivityNames.EdgeGroupProcess
+    /// -- ActivityNames.ExecutorProcess (ReverseTextExecutor)
+    /// --- ActivityNames.MessageSend
+    /// </remarks>
+    /// <returns>The created workflow.</returns>
+    private static Workflow CreateWorkflow()
+    {
+        // Create the executors
+        Func<string, string> uppercaseFunc = s => s.ToUpperInvariant();
+        var uppercase = uppercaseFunc.BindAsExecutor("UppercaseExecutor");
+
+        Func<string, string> reverseFunc = s => new string(s.Reverse().ToArray());
+        var reverse = reverseFunc.BindAsExecutor("ReverseTextExecutor");
+
+        // Build the workflow by connecting executors sequentially
+        WorkflowBuilder builder = new(uppercase);
+        builder.AddEdge(uppercase, reverse).WithOutputFrom(reverse);
+
+        return builder.Build();
+    }
+
+    private static Dictionary<string, int> GetExpectedActivityNameCounts() =>
+        new()
+        {
+            { ActivityNames.WorkflowBuild, 1 },
+            { ActivityNames.WorkflowRun, 1 },
+            { ActivityNames.EdgeGroupProcess, 2 },
+            { ActivityNames.ExecutorProcess, 2 },
+            { ActivityNames.MessageSend, 2 }
+        };
+
+    private static InProcessExecutionEnvironment GetExecutionEnvironment(string name) =>
+        name switch
+        {
+            "Default" => InProcessExecution.Default,
+            "Lockstep" => InProcessExecution.Lockstep,
+            "OffThread" => InProcessExecution.OffThread,
+            "Concurrent" => InProcessExecution.Concurrent,
+            _ => throw new ArgumentException($"Unknown execution environment name: {name}")
+        };
+
+    public void Dispose()
+    {
+        if (!this._isDisposed)
+        {
+            this._activityListener?.Dispose();
+            this._isDisposed = true;
+        }
+    }
+
+    private async Task TestWorkflowEndToEndActivitiesAsync(string executionEnvironmentName)
+    {
+        // Arrange
+        // Create a test activity to correlate captured activities
+        using var testActivity = new Activity("ObservabilityTest").Start();
+
+        // Act
+        var workflow = CreateWorkflow();
+        var executionEnvironment = GetExecutionEnvironment(executionEnvironmentName);
+        Run run = await executionEnvironment.RunAsync(workflow, "Hello, World!");
+        await run.DisposeAsync();
+
+        await Task.Delay(100); // Allow time for activities to be captured
+
+        // Assert
+        var capturedActivities = this._capturedActivities.Where(a => a.RootId == testActivity.RootId).ToList();
+        capturedActivities.Should().HaveCount(8, "Exactly 8 activities should be created.");
+
+        // Make sure all expected activities exist and have the correct count
+        foreach (var kvp in GetExpectedActivityNameCounts())
+        {
+            var activityName = kvp.Key;
+            var expectedCount = kvp.Value;
+            var actualCount = capturedActivities.Count(a => a.OperationName == activityName);
+            actualCount.Should().Be(expectedCount, $"Activity '{activityName}' should occur {expectedCount} times.");
+        }
+
+        // Verify WorkflowRun activity events include workflow lifecycle events
+        var workflowRunActivity = capturedActivities.First(a => a.OperationName == ActivityNames.WorkflowRun);
+        var activityEvents = workflowRunActivity.Events.ToList();
+        activityEvents.Should().Contain(e => e.Name == EventNames.WorkflowStarted, "activity should have workflow started event");
+        activityEvents.Should().Contain(e => e.Name == EventNames.WorkflowCompleted, "activity should have workflow completed event");
+    }
+
+    [Fact]
+    public async Task CreatesWorkflowEndToEndActivities_WithCorrectName_DefaultAsync()
+    {
+        await this.TestWorkflowEndToEndActivitiesAsync("Default");
+    }
+
+    [Fact]
+    public async Task CreatesWorkflowEndToEndActivities_WithCorrectName_OffThreadAsync()
+    {
+        await this.TestWorkflowEndToEndActivitiesAsync("OffThread");
+    }
+
+    [Fact]
+    public async Task CreatesWorkflowEndToEndActivities_WithCorrectName_ConcurrentAsync()
+    {
+        await this.TestWorkflowEndToEndActivitiesAsync("Concurrent");
+    }
+
+    [Fact]
+    public async Task CreatesWorkflowEndToEndActivities_WithCorrectName_LockstepAsync()
+    {
+        await this.TestWorkflowEndToEndActivitiesAsync("Lockstep");
+    }
+
+    [Fact]
+    public async Task CreatesWorkflowActivities_WithCorrectNameAsync()
+    {
+        // Arrange
+        // Create a test activity to correlate captured activities
+        using var testActivity = new Activity("ObservabilityTest").Start();
+
+        // Act
+        CreateWorkflow();
+        await Task.Delay(100); // Allow time for activities to be captured
+
+        // Assert
+        var capturedActivities = this._capturedActivities.Where(a => a.RootId == testActivity.RootId).ToList();
+        capturedActivities.Should().HaveCount(1, "Exactly 1 activity should be created.");
+        capturedActivities[0].OperationName.Should().Be(ActivityNames.WorkflowBuild,
+            "The activity should have the correct operation name for workflow build.");
+
+        var events = capturedActivities[0].Events.ToList();
+        events.Should().Contain(e => e.Name == EventNames.BuildStarted, "activity should have build started event");
+        events.Should().Contain(e => e.Name == EventNames.BuildValidationCompleted, "activity should have build validation completed event");
+        events.Should().Contain(e => e.Name == EventNames.BuildCompleted, "activity should have build completed event");
+
+        var tags = capturedActivities[0].Tags.ToDictionary(t => t.Key, t => t.Value);
+        tags.Should().ContainKey(Tags.WorkflowId);
+        tags.Should().ContainKey(Tags.WorkflowDefinition);
+    }
+}