Core - Fix data model paths around saving, removed children and stored types

- The constructors saved the path before setting it up, while it was
  still invalid, so a new path stored nothing and didn't follow its data
  model leaving and returning to the store until it was saved.
- Removing the dynamic child a path points to left the path valid and
  reading a default value, it now becomes invalid like when the child
  was never there.
- The stored type of a path is now also looked up in all loaded
  assemblies, Type.GetType only found it in Artemis.Core and the .NET
  libraries, not in plugins or SkiaSharp.

src/Artemis.Core.Tests/DataModels/DataModelPathTests.cs

@@ -340,7 +340,7 @@ public class DataModelPathTests : IDisposable
     }
 
     [Fact]
-    public void RemovingTheDynamicChild_LeavesThePathValid()
+    public void RemovingTheDynamicChild_MakesThePathInvalid()
     {
         DataModel.AddDynamicChild("Extra", 5);
         using DataModelPath path = new(DataModel, "Extra");
@@ -349,25 +349,34 @@ public class DataModelPathTests : IDisposable
 
         DataModel.RemoveDynamicChildByKey("Extra");
 
-        // Pinned as-is: the segment only invalidates the path when the value of the removed child is the data model the
-        // segment looks in, rather than when the child it points to is removed. So the path stays valid and reads the
-        // default value instead of becoming invalid.
-        path.IsValid.ShouldBeTrue();
-        path.GetValue().ShouldBe(0);
-        invalidated.ShouldBe(0);
+        path.IsValid.ShouldBeFalse();
+        path.GetValue().ShouldBeNull();
+        invalidated.ShouldBe(1);
     }
 
     [Fact]
-    public void RemovingADynamicDataModel_LeavesThePathThroughItValid()
+    public void RemovingTheDynamicChild_AndAddingItAgain_MakesThePathValidAgain()
+    {
+        DataModel.AddDynamicChild("Extra", 5);
+        using DataModelPath path = new(DataModel, "Extra");
+        DataModel.RemoveDynamicChildByKey("Extra");
+
+        DataModel.AddDynamicChild("Extra", 6);
+
+        path.IsValid.ShouldBeTrue();
+        path.GetValue().ShouldBe(6);
+    }
+
+    [Fact]
+    public void RemovingADynamicDataModel_MakesThePathThroughItInvalid()
     {
         DataModel.AddDynamicChild("Extra", new TestChildDataModel {Integer = 4}, "Extra data");
         using DataModelPath path = new(DataModel, "Extra.Integer");
 
         DataModel.RemoveDynamicChildByKey("Extra");
 
-        // Pinned as-is, see RemovingTheDynamicChild_LeavesThePathValid
-        path.IsValid.ShouldBeTrue();
-        path.GetValue().ShouldBe(0);
+        path.IsValid.ShouldBeFalse();
+        path.GetValue().ShouldBeNull();
     }
 
     [Fact]
@@ -450,20 +459,17 @@ public class DataModelPathTests : IDisposable
     }
 
     [Fact]
-    public void NewPath_DoesNotFollowTheStoreUntilItIsSaved()
+    public void NewPath_FollowsTheStoreWithoutBeingSaved()
     {
         using DataModelPath path = new(DataModel, "Integer");
 
-        // Pinned as-is: the constructors call Save before the path is set up, while it is still invalid, so nothing is
-        // saved and the entity has no data model ID. The path only reacts to its data model leaving and returning to the
-        // store once Save is called. Looks like Save should be called after Initialize.
-        path.Entity.DataModelId.ShouldBeNull();
-        path.Entity.Path.ShouldBe("");
+        path.Entity.DataModelId.ShouldBe(_module.Id);
+        path.Entity.Path.ShouldBe("Integer");
 
         RemoveFromStore();
 
-        path.IsValid.ShouldBeTrue();
-        path.Target.ShouldBeSameAs(DataModel);
+        path.IsValid.ShouldBeFalse();
+        path.Target.ShouldBeNull();
     }
 
     [Fact]
@@ -540,7 +546,7 @@ public class DataModelPathTests : IDisposable
     }
 
     [Fact]
-    public void InvalidPath_CannotFallBackToATypeOutsideTheCoreLibraries()
+    public void InvalidPath_FallsBackToATypeOutsideTheCoreLibraries()
     {
         using DataModelPath valid = new(DataModel, "Enum");
         valid.Save();
@@ -548,9 +554,15 @@ public class DataModelPathTests : IDisposable
 
         using DataModelPath path = new(new DataModelPathEntity {Path = "Enum", DataModelId = "Missing-12345678", Type = valid.Entity.Type});
 
-        // Pinned as-is: the type is saved by its full name without the assembly, which Type.GetType can only find in
-        // Artemis.Core and the .NET libraries, so types from plugins (and SkiaSharp, like SKColor) can't be found again.
-        path.GetPropertyType().ShouldBeNull();
+        path.GetPropertyType().ShouldBe(typeof(TestEnum));
+    }
+
+    [Fact]
+    public void InvalidPath_FallsBackToASkiaSharpType()
+    {
+        using DataModelPath path = new(new DataModelPathEntity {Path = "Color", DataModelId = "Missing-12345678", Type = typeof(SKColor).FullName});
+
+        path.GetPropertyType().ShouldBe(typeof(SKColor));
     }
 
     [Fact]

src/Artemis.Core/Models/Profile/DataModel/DataModelPath.cs

@@ -29,8 +29,8 @@ public class DataModelPath : IStorageModel, IDisposable, IPluginFeatureDependent
 
         _segments = [];
 
-        Save();
         Initialize();
+        Save();
         SubscribeToDataModelStore();
     }
 
@@ -47,8 +47,8 @@ public class DataModelPath : IStorageModel, IDisposable, IPluginFeatureDependent
 
         _segments = [];
 
-        Save();
         Initialize();
+        Save();
         SubscribeToDataModelStore();
     }
 
@@ -67,8 +67,8 @@ public class DataModelPath : IStorageModel, IDisposable, IPluginFeatureDependent
 
         _segments = [];
 
-        Save();
         Initialize();
+        Save();
         SubscribeToDataModelStore();
     }
 
@@ -165,11 +165,20 @@ public class DataModelPath : IStorageModel, IDisposable, IPluginFeatureDependent
         
         // Fall back to stored type
         if (!string.IsNullOrWhiteSpace(Entity.Type))
-            return Type.GetType(Entity.Type);
+            return FindType(Entity.Type);
 
         return null;
     }
 
+    private static Type? FindType(string fullName)
+    {
+        // The type is stored without its assembly, Type.GetType only finds it in Artemis.Core and the .NET libraries. Types
+        // of plugins and other libraries (like SKColor) are found by looking through the loaded assemblies
+        return Type.GetType(fullName) ?? AppDomain.CurrentDomain.GetAssemblies()
+            .Select(assembly => assembly.GetType(fullName))
+            .FirstOrDefault(type => type != null);
+    }
+
     /// <summary>
     ///     Gets the property description of the property this path points to
     /// </summary>

src/Artemis.Core/Models/Profile/DataModel/DataModelPathSegment.cs

@@ -286,8 +286,16 @@ public class DataModelPathSegment : IDisposable
 
     private void DynamicChildOnDynamicChildRemoved(object? sender, DynamicDataModelChildEventArgs e)
     {
-        if (e.DynamicChild.BaseValue == _dynamicDataModel)
+        // Like when a child is added, initialize the path again so it no longer points to the removed child
+        if (e.Key == Identifier)
+        {
             DataModelPath.Invalidate();
+            DataModelPath.Initialize();
+        }
+        else if (e.DynamicChild.BaseValue == _dynamicDataModel)
+        {
+            DataModelPath.Invalidate();
+        }
     }
 
     /// <inheritdoc />