Fixed end-user transactions and added unit tests

src/Venflow/Venflow.Tests/Models/Person.cs

@@ -15,6 +15,6 @@ public class Person
         [NotMapped]
         public string Stuff { get; set; }
 
-        public List<Email> Emails { get; set; }
+        public IList<Email> Emails { get; set; }
     }
 }

src/Venflow/Venflow.Tests/TransactionTests/TransactionTests.cs

@@ -0,0 +1,94 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Reflection;
+using System.Threading.Tasks;
+using Npgsql;
+using Venflow.Tests.Models;
+using Xunit;
+
+namespace Venflow.Tests.TransactionTests
+{
+    public class TransactionTests : TestBase
+    {
+        [Fact]
+        public async Task ReuseTransactionAsync()
+        {
+            await using var transaction = await Database.BeginTransactionAsync();
+
+            Assert.Equal(transaction, await Database.BeginTransactionAsync());
+        }
+
+        [Fact]
+        public async Task RollbackToTransactionSavepointAsync()
+        {
+            await using var transaction = await Database.BeginTransactionAsync();
+
+            await Assert.ThrowsAsync<NotImplementedException>(() => Database.People.InsertAsync(new Person { Emails = new ThrowingEmailList() }));
+
+            var transactionType = transaction.GetType();
+            var npgsqlTransactionType = typeof(NpgsqlTransaction);
+
+            Assert.False((bool)transactionType.GetProperty("IsDisposed", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(transaction));
+            Assert.False((bool)npgsqlTransactionType.GetProperty("IsCompleted", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(transaction.GetNpgsqlTransaction()));
+        }
+
+        private class ThrowingEmailList : IList<Email>
+        {
+            public Email this[int index] { get => throw new NotImplementedException(); set => throw new NotImplementedException(); }
+
+            public int Count => throw new NotImplementedException();
+            public bool IsReadOnly => throw new NotImplementedException();
+
+            public void Add(Email item)
+            {
+                throw new System.NotImplementedException();
+            }
+
+            public void Clear()
+            {
+                throw new System.NotImplementedException();
+            }
+
+            public bool Contains(Email item)
+            {
+                throw new System.NotImplementedException();
+            }
+
+            public void CopyTo(Email[] array, int arrayIndex)
+            {
+                throw new System.NotImplementedException();
+            }
+
+            public IEnumerator<Email> GetEnumerator()
+            {
+                throw new System.NotImplementedException();
+            }
+
+            public int IndexOf(Email item)
+            {
+                throw new System.NotImplementedException();
+            }
+
+            public void Insert(int index, Email item)
+            {
+                throw new System.NotImplementedException();
+            }
+
+            public bool Remove(Email item)
+            {
+                throw new System.NotImplementedException();
+            }
+
+            public void RemoveAt(int index)
+            {
+                throw new System.NotImplementedException();
+            }
+
+            IEnumerator IEnumerable.GetEnumerator()
+            {
+                throw new System.NotImplementedException();
+            }
+        }
+    }
+}

src/Venflow/Venflow/Database.cs

@@ -81,9 +81,9 @@ protected Database(DatabaseOptionsBuilder optionsBuilder)
             await ValidateConnectionAsync();
 
 #if NET48
-            return !HasActiveTransaction ? _activeTransaction : _activeTransaction = new DatabaseTransaction(GetConnection().BeginTransaction());
+            return HasActiveTransaction ? _activeTransaction! : _activeTransaction = new DatabaseTransaction(GetConnection().BeginTransaction());
 #else
-            return !HasActiveTransaction ? _activeTransaction : _activeTransaction = new DatabaseTransaction(await GetConnection().BeginTransactionAsync(cancellationToken));
+            return HasActiveTransaction ? _activeTransaction! : _activeTransaction = new DatabaseTransaction(await GetConnection().BeginTransactionAsync(cancellationToken));
 #endif
         }
 
@@ -103,9 +103,9 @@ protected Database(DatabaseOptionsBuilder optionsBuilder)
             await ValidateConnectionAsync();
 
 #if NET48
-            return !HasActiveTransaction ? _activeTransaction : _activeTransaction = new DatabaseTransaction(GetConnection().BeginTransaction());
+            return HasActiveTransaction ? _activeTransaction! : _activeTransaction = new DatabaseTransaction(GetConnection().BeginTransaction());
 #else
-            return !HasActiveTransaction ? _activeTransaction : _activeTransaction = new DatabaseTransaction(await GetConnection().BeginTransactionAsync(isolationLevel, cancellationToken));
+            return HasActiveTransaction ? _activeTransaction! : _activeTransaction = new DatabaseTransaction(await GetConnection().BeginTransactionAsync(isolationLevel, cancellationToken));
 #endif
         }
 
@@ -123,6 +123,7 @@ protected Database(DatabaseOptionsBuilder optionsBuilder)
 #if NET48
             return _activeTransaction = new DatabaseTransaction(GetConnection().BeginTransaction());
 #else
+
             return _activeTransaction = new DatabaseTransaction(await GetConnection().BeginTransactionAsync(cancellationToken));
 #endif
         }