Refactored and improved UOW. Added simple UOW middleware. Created a unit test for UOW.

src/Volo.Abp.AspNetCore.Mvc/Volo/Abp/AspNetCore/Mvc/Uow/AbpUnitOfWorkMiddleware.cs

@@ -0,0 +1,25 @@
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using Volo.Abp.Uow;
+
+namespace Volo.Abp.AspNetCore.Mvc.Uow
+{
+    class AbpUnitOfWorkMiddleware
+    {
+        private readonly RequestDelegate _next;
+
+        public AbpUnitOfWorkMiddleware(RequestDelegate next)
+        {
+            _next = next;
+        }
+
+        public async Task Invoke(HttpContext httpContext, IUnitOfWorkManager unitOfWorkManager)
+        {
+            using (var uow = unitOfWorkManager.Begin())
+            {
+                await _next(httpContext);
+                await uow.CompleteAsync();
+            }
+        }
+    }
+}

src/Volo.Abp/Volo/Abp/Uow/AmbientUnitOfWork.cs

@@ -6,18 +6,18 @@ namespace Volo.Abp.Uow
     [ExposeServices(typeof(IAmbientUnitOfWork), typeof(IUnitOfWorkAccessor))]
     public class AmbientUnitOfWork : IAmbientUnitOfWork, ISingletonDependency
     {
-        public IUnitOfWork UnitOfWork => _currentUowInfo.Value;
+        public IUnitOfWork UnitOfWork => _currentUow.Value;
 
-        private readonly AsyncLocal<IUnitOfWork> _currentUowInfo;
+        private readonly AsyncLocal<IUnitOfWork> _currentUow;
 
         public AmbientUnitOfWork()
         {
-            _currentUowInfo = new AsyncLocal<IUnitOfWork>();
+            _currentUow = new AsyncLocal<IUnitOfWork>();
         }
 
         public void SetUnitOfWork(IUnitOfWork unitOfWork)
         {
-            _currentUowInfo.Value = unitOfWork;
+            _currentUow.Value = unitOfWork;
         }
     }
 }

src/Volo.Abp/Volo/Abp/Uow/ChildUnitOfWork.cs

@@ -7,6 +7,8 @@ namespace Volo.Abp.Uow
 {
     internal class ChildUnitOfWork : IUnitOfWork
     {
+        public Guid Id => _parent.Id;
+
         public event EventHandler Completed;
         public event EventHandler<UnitOfWorkFailedEventArgs> Failed;
         public event EventHandler Disposed;
@@ -60,5 +62,10 @@ namespace Volo.Abp.Uow
         {
 
         }
+
+        public override string ToString()
+        {
+            return $"[UnitOfWork {Id}]";
+        }
     }
 }

src/Volo.Abp/Volo/Abp/Uow/IBasicUnitOfWork.cs

@@ -7,6 +7,8 @@ namespace Volo.Abp.Uow
     //TODO: Find a better naming :(
     public interface IBasicUnitOfWork : IDisposable
     {
+        Guid Id { get; }
+
         event EventHandler Completed;
 
         event EventHandler<UnitOfWorkFailedEventArgs> Failed;

src/Volo.Abp/Volo/Abp/Uow/IDatabaseApiContainer.cs

@@ -10,6 +10,6 @@ namespace Volo.Abp.Uow
         IDatabaseApi FindDatabaseApi([NotNull] string id);
 
         [NotNull]
-        IDatabaseApi GetOrAddDatabaseApi(string id, Func<IDatabaseApi> factory);
+        IDatabaseApi GetOrAddDatabaseApi([NotNull] string id, [NotNull] Func<IDatabaseApi> factory);
     }
 }

src/Volo.Abp/Volo/Abp/Uow/UnitOfWork.cs

@@ -8,6 +8,8 @@ namespace Volo.Abp.Uow
 {
     public class UnitOfWork : IUnitOfWork, ITransientDependency
     {
+        public Guid Id { get; } = Guid.NewGuid();
+
         public event EventHandler Completed;
         public event EventHandler<UnitOfWorkFailedEventArgs> Failed;
         public event EventHandler Disposed;
@@ -27,23 +29,6 @@ namespace Volo.Abp.Uow
             _databaseApis = new Dictionary<string, IDatabaseApi>();
         }
 
-        public void Dispose()
-        {
-            if (_isDisposed)
-            {
-                return;
-            }
-
-            _isDisposed = true;
-
-            if (!_isCompleted || _exception != null)
-            {
-                OnFailed(_exception);
-            }
-
-            OnDisposed();
-        }
-
         public void SaveChanges()
         {
             foreach (var databaseApi in _databaseApis.Values)
@@ -122,6 +107,23 @@ namespace Volo.Abp.Uow
             Disposed.InvokeSafely(this);
         }
 
+        public void Dispose()
+        {
+            if (_isDisposed)
+            {
+                return;
+            }
+
+            _isDisposed = true;
+
+            if (!_isCompleted || _exception != null)
+            {
+                OnFailed(_exception);
+            }
+
+            OnDisposed();
+        }
+
         private void PreventMultipleComplete()
         {
             if (_isCompleted)
@@ -131,5 +133,10 @@ namespace Volo.Abp.Uow
 
             _isCompleted = true;
         }
+
+        public override string ToString()
+        {
+            return $"[UnitOfWork {Id}]";
+        }
     }
 }

src/Volo.Abp/Volo/Abp/Uow/UnitOfWorkManager.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Diagnostics;
 using Microsoft.Extensions.DependencyInjection;
 using Volo.Abp.DependencyInjection;
 
@@ -41,27 +40,13 @@ namespace Volo.Abp.Uow
 
             _ambientUnitOfWork.SetUnitOfWork(unitOfWork);
 
-            Debug.Assert(
-                _ambientUnitOfWork.UnitOfWork != null,
-                "_ambientUnitOfWork.UnitOfWork can not be null since it's set by _ambientUnitOfWork.SetUnitOfWork method!"
-            );
-
-            unitOfWork.Completed += (sender, args) =>
-            {
-                _ambientUnitOfWork.SetUnitOfWork(parentUow);
-            };
-
-            unitOfWork.Failed += (sender, args) =>
-            {
-                _ambientUnitOfWork.SetUnitOfWork(parentUow);
-            };
-
             unitOfWork.Disposed += (sender, args) =>
             {
+                _ambientUnitOfWork.SetUnitOfWork(parentUow);
                 scope.Dispose();
             };
 
-            return _ambientUnitOfWork.UnitOfWork;
+            return unitOfWork;
         }
     }
 }

test/Volo.Abp.Tests/Volo/Abp/Uow/UnitOfWork_Ambient_Scope_Tests.cs

@@ -0,0 +1,43 @@
+using System.Threading.Tasks;
+using Microsoft.Extensions.DependencyInjection;
+using Shouldly;
+using Volo.Abp.Modularity;
+using Volo.Abp.TestBase;
+using Xunit;
+
+namespace Volo.Abp.Uow
+{
+    public class UnitOfWork_Ambient_Scope_Tests : AbpIntegratedTest<IndependentEmptyModule>
+    {
+        private readonly IUnitOfWorkManager _unitOfWorkManager;
+
+        public UnitOfWork_Ambient_Scope_Tests()
+        {
+            _unitOfWorkManager = ServiceProvider.GetRequiredService<IUnitOfWorkManager>();
+        }
+
+        [Fact]
+        public async Task UnitOfWorkManager_Current_Should_Set_Correctly()
+        {
+            _unitOfWorkManager.Current.ShouldBeNull();
+
+            using (var uow1 = _unitOfWorkManager.Begin())
+            {
+                _unitOfWorkManager.Current.ShouldNotBeNull();
+                _unitOfWorkManager.Current.ShouldBe(uow1);
+
+                using (var uow2 = _unitOfWorkManager.Begin())
+                {
+                    _unitOfWorkManager.Current.ShouldNotBeNull();
+                    _unitOfWorkManager.Current.Id.ShouldBe(uow1.Id);
+
+                    await uow2.CompleteAsync();
+                }
+
+                await uow1.CompleteAsync();
+            }
+
+            _unitOfWorkManager.Current.ShouldBeNull();
+        }
+    }
+}