Fix StopAsync to properly await async task completion in workflow steps

src/WorkflowCore/Services/BackgroundTasks/QueueConsumer.cs

@@ -24,6 +24,8 @@ internal abstract class QueueConsumer : IBackgroundTask
         protected Task DispatchTask;        
         private CancellationTokenSource _cancellationTokenSource;
         private Dictionary<string, EventWaitHandle> _activeTasks;
+        private List<Task> _runningTasks;
+        private readonly object _runningTasksLock = new object();
         private ConcurrentHashSet<string> _secondPasses;
 
         protected QueueConsumer(IQueueProvider queueProvider, ILoggerFactory loggerFactory, WorkflowOptions options)
@@ -33,6 +35,7 @@ protected QueueConsumer(IQueueProvider queueProvider, ILoggerFactory loggerFacto
             Logger = loggerFactory.CreateLogger(GetType());
 
             _activeTasks = new Dictionary<string, EventWaitHandle>();
+            _runningTasks = new List<Task>();
             _secondPasses = new ConcurrentHashSet<string>();
         }
 
@@ -115,6 +118,10 @@ private async Task Execute()
                         _activeTasks.Add(item, waitHandle);
                     }
                     var task = ExecuteItem(item, waitHandle, activity);
+                    lock (_runningTasksLock)
+                    {
+                        _runningTasks.Add(task);
+                    }
                 }
                 catch (OperationCanceledException)
                 {
@@ -138,6 +145,25 @@ private async Task Execute()
 
             foreach (var handle in toComplete)
                 handle.WaitOne();
+
+            // Also await all running tasks to ensure proper async completion
+            Task[] tasksToAwait;
+            lock (_runningTasksLock)
+            {
+                tasksToAwait = _runningTasks.ToArray();
+            }
+
+            if (tasksToAwait.Length > 0)
+            {
+                try
+                {
+                    await Task.WhenAll(tasksToAwait);
+                }
+                catch
+                {
+                    // Individual task exceptions are already logged in ExecuteItem
+                }
+            }
         }
 
         private async Task ExecuteItem(string itemId, EventWaitHandle waitHandle, Activity activity)

test/WorkflowCore.IntegrationTests/Scenarios/StopAsyncScenario.cs

@@ -0,0 +1,97 @@
+using System;
+using System.Diagnostics;
+using System.Threading.Tasks;
+using WorkflowCore.Interface;
+using WorkflowCore.Models;
+using Xunit;
+using FluentAssertions;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace WorkflowCore.IntegrationTests.Scenarios
+{
+    public class StopAsyncWorkflow : IWorkflow
+    {
+        internal static DateTime? StepStartTime = null;
+        internal static DateTime? StepEndTime = null;
+
+        public string Id => "StopAsyncWorkflow";
+        public int Version => 1;
+        public void Build(IWorkflowBuilder<Object> builder)
+        {
+            builder
+                .StartWith<LongRunningStep>();
+        }
+    }
+
+    internal class LongRunningStep : StepBodyAsync
+    {
+        public override async Task<ExecutionResult> RunAsync(IStepExecutionContext context)
+        {
+            StopAsyncWorkflow.StepStartTime = DateTime.Now;
+            await Task.Delay(5000); // 5 second delay
+            StopAsyncWorkflow.StepEndTime = DateTime.Now;
+            return ExecutionResult.Next();
+        }
+    }
+
+    public class StopAsyncScenario : IDisposable
+    {   
+        protected IWorkflowHost Host;
+        protected IPersistenceProvider PersistenceProvider;
+
+        public StopAsyncScenario()
+        {
+            //setup dependency injection
+            IServiceCollection services = new ServiceCollection();
+            services.AddLogging();
+            services.AddWorkflow(options => options.UsePollInterval(TimeSpan.FromSeconds(3)));
+
+            var serviceProvider = services.BuildServiceProvider();
+
+            PersistenceProvider = serviceProvider.GetService<IPersistenceProvider>();
+            Host = serviceProvider.GetService<IWorkflowHost>();
+            Host.RegisterWorkflow<StopAsyncWorkflow, Object>();
+            Host.Start();
+        }
+
+        [Fact]
+        public async Task StopAsync_should_wait_for_running_steps_to_complete()
+        {
+            // Arrange
+            StopAsyncWorkflow.StepStartTime = null;
+            StopAsyncWorkflow.StepEndTime = null;
+
+            // Start a workflow with a long-running step
+            var workflowId = await Host.StartWorkflow<Object>("StopAsyncWorkflow", null);
+
+            // Wait for the step to start executing
+            var waitCount = 0;
+            while (StopAsyncWorkflow.StepStartTime == null && waitCount < 50)
+            {
+                await Task.Delay(100);
+                waitCount++;
+            }
+
+            StopAsyncWorkflow.StepStartTime.Should().NotBeNull("the step should have started before stopping");
+            StopAsyncWorkflow.StepEndTime.Should().BeNull("the step should still be running");
+
+            // Act - Call StopAsync which should wait for the step to complete
+            var stopwatch = Stopwatch.StartNew();
+            await Host.StopAsync(default);
+            stopwatch.Stop();
+
+            // Assert
+            // The step should have completed
+            StopAsyncWorkflow.StepEndTime.Should().NotBeNull("the step should have completed before StopAsync returned");
+
+            // StopAsync should have taken at least 3 seconds (the remaining delay time)
+            stopwatch.ElapsedMilliseconds.Should().BeGreaterOrEqualTo(3000, 
+                "StopAsync should wait for the running step to complete");
+        }
+
+        public void Dispose()
+        {
+            // Dispose is intentionally empty to avoid double-stop
+        }
+    }
+}