Tests pass

Nexus-Mods · Dec 19, 2023 · de00849 · de00849
1 parent 8ef2e14
commit de00849
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Showing 6 changed files with 40 additions and 12 deletions.
diff --git a/src/NexusMods.EventSourcing.Abstractions/IEntityContext.cs b/src/NexusMods.EventSourcing.Abstractions/IEntityContext.cs
@@ -39,17 +39,19 @@ public interface IEntityContext
     public ITransaction Begin();
 
     /// <summary>
-    /// Gets the value of the attribute for the given entity.
+    /// Gets the value of the attribute for the given entity. If createIfMissing is true, then the attribute will be
+    /// created if it does not exist, this is useful for attributes that have a default "empty" value.
     /// </summary>
     /// <param name="ownerId"></param>
     /// <param name="attributeDefinition"></param>
     /// <param name="accumulator"></param>
+    /// <param name="createIfMissing"></param>
     /// <typeparam name="TType"></typeparam>
     /// <typeparam name="TOwner"></typeparam>
     /// <typeparam name="TAttribute"></typeparam>
     /// <typeparam name="TAccumulator"></typeparam>
     /// <returns></returns>
-    bool GetReadOnlyAccumulator<TOwner, TAttribute, TAccumulator>(EntityId<TOwner> ownerId, TAttribute attributeDefinition, out TAccumulator accumulator)
+    bool GetReadOnlyAccumulator<TOwner, TAttribute, TAccumulator>(EntityId<TOwner> ownerId, TAttribute attributeDefinition, out TAccumulator accumulator, bool createIfMissing = false)
         where TOwner : IEntity
         where TAttribute : IAttribute<TAccumulator>
         where TAccumulator : IAccumulator;

diff --git a/src/NexusMods.EventSourcing.Abstractions/MultiEntityAttributeDefinition.cs b/src/NexusMods.EventSourcing.Abstractions/MultiEntityAttributeDefinition.cs
@@ -74,7 +74,7 @@ public ReadOnlyObservableCollection<TOther> Get(TOwner entity)
     {
         if (!entity.Context
                 .GetReadOnlyAccumulator<TOwner, MultiEntityAttributeDefinition<TOwner, TOther>,
-                    MultiEntityAccumulator<TOther>>(entity.Id, this, out var accumulator))
+                    MultiEntityAccumulator<TOther>>(entity.Id, this, out var accumulator, true))
             throw new InvalidOperationException("No accumulator found for entity");
 
         accumulator.Init(entity.Context);

diff --git a/src/NexusMods.EventSourcing/EntityContext.cs b/src/NexusMods.EventSourcing/EntityContext.cs
@@ -105,7 +105,7 @@ public TransactionId Add<TEvent>(TEvent newEvent) where TEvent : IEvent
 
     /// <inheritdoc />
     public bool GetReadOnlyAccumulator<TOwner, TAttribute, TAccumulator>(EntityId<TOwner> ownerId, TAttribute attributeDefinition,
-        out TAccumulator accumulator)
+        out TAccumulator accumulator, bool createIfMissing = false)
         where TOwner : IEntity
         where TAttribute : IAttribute<TAccumulator>
         where TAccumulator : IAccumulator
@@ -116,6 +116,19 @@ public bool GetReadOnlyAccumulator<TOwner, TAttribute, TAccumulator>(EntityId<TO
             accumulator = (TAccumulator) value;
             return true;
         }
+
+        if (createIfMissing)
+        {
+            var newAccumulator = attributeDefinition.CreateAccumulator();
+            if (values.TryAdd(attributeDefinition, newAccumulator))
+            {
+                accumulator = newAccumulator;
+                return true;
+            }
+            accumulator = (TAccumulator) values[attributeDefinition];
+            return true;
+        }
+
         accumulator = default!;
         return false;
     }

diff --git a/src/NexusMods.EventSourcing/Transaction.cs b/src/NexusMods.EventSourcing/Transaction.cs
@@ -17,7 +17,9 @@ public TransactionId Commit()
     {
         if (events.Count == 1)
             return context.Add(events[0]);
-        return context.Add(new TransactionEvent(events.ToArray()));
+        var id = context.Add(new TransactionEvent(events.ToArray()));
+        events.Clear();
+        return id;
     }
 
     public void Dispose()

diff --git a/tests/NexusMods.EventSourcing.TestModel/Events/RenameLoadout.cs b/tests/NexusMods.EventSourcing.TestModel/Events/RenameLoadout.cs
@@ -12,4 +12,9 @@ public void Apply<T>(T context) where T : IEventContext
     {
         Loadout._name.Set(context, Id, Name);
     }
+
+    public static void Create(ITransaction tx, EntityId<Loadout> id, string name)
+    {
+        tx.Add(new RenameLoadout(id, name));
+    }
 }
diff --git a/tests/NexusMods.EventSourcing.Tests/BasicFunctionalityTests.cs b/tests/NexusMods.EventSourcing.Tests/BasicFunctionalityTests.cs
@@ -99,22 +99,28 @@ public void CanGetSingletonEntities()
     [Fact]
     public void UpdatingAValueCallesNotifyPropertyChanged()
     {
-        var loadout = _ctx.Get<LoadoutRegistry>();
-        loadout.Loadouts.Should().BeEmpty();
+        var loadouts = _ctx.Get<LoadoutRegistry>();
+        loadouts.Loadouts.Should().BeEmpty();
+
+        using var tx = _ctx.Begin();
+        var loadoutId = CreateLoadout.Create(tx, "Test");
+        tx.Commit();
+
+        var loadout = _ctx.Get(loadoutId);
 
         var called = false;
         loadout.PropertyChanged += (sender, args) =>
         {
             called = true;
-            args.PropertyName.Should().Be(nameof(LoadoutRegistry.Loadouts));
+            args.PropertyName.Should().Be(nameof(Loadout.Name));
         };
 
-        using var tx = _ctx.Begin();
-        var loadoutId = CreateLoadout.Create(tx, "Test");
-        tx.Commit();
+        using var tx2 = _ctx.Begin();
+        RenameLoadout.Create(tx2, loadoutId, "New Name");
+        tx2.Commit();
 
         called.Should().BeTrue();
-        loadout.Loadouts.Should().NotBeEmpty();
+        loadout.Name.Should().Be("New Name");
     }
 
     [Fact]