Fix overriding Id for automapping (#671)

Fixes #431

+semver:fix

src/FluentNHibernate.Specs/Automapping/Fixtures/EntityWithDifferentId.cs

@@ -0,0 +1,9 @@
+using System;
+
+namespace FluentNHibernate.Specs.Automapping.Fixtures;
+
+public class EntityWithDifferentId
+{
+    public virtual int DestinationId { get; set; }
+    public virtual Guid Id { get; set; }
+}

src/FluentNHibernate.Specs/Automapping/OverrideSpecs.cs

@@ -8,6 +8,7 @@
 using FluentNHibernate.Specs.ExternalFixtures.Overrides;
 using Machine.Specifications;
 using FluentAssertions;
+using FluentNHibernate.MappingModel.Identity;
 
 namespace FluentNHibernate.Specs.Automapping;
 
@@ -81,6 +82,29 @@ public class when_using_an_automapping_override_to_specify_a_discriminator
     static ClassMapping mapping;
 }
 
+public class when_using_an_automapping_override_to_specify_a_different_id
+{
+    Establish context = () =>
+        model = AutoMap.Source(new StubTypeSource(typeof(EntityWithDifferentId)))
+            .Override<EntityWithDifferentId>(map =>
+                map.Id(x => x.DestinationId));
+
+    Because of = () =>
+        mapping = model.BuildMappingFor<EntityWithDifferentId>();
+
+    It should_map_the_id = () =>
+        mapping.Id.Should().NotBeNull();
+
+    It should_map_id_as_id_mapping = () =>
+        mapping.Id.Should().BeOfType<IdMapping>();
+
+    It should_map_id_as_different_id = () =>
+        ((IdMapping)mapping.Id).Name.Should().Be("DestinationId");
+
+    static AutoPersistenceModel model;
+    static ClassMapping mapping;
+}
+
 [Subject(typeof(IAutoMappingOverride<>))]
 public class when_using_multiple_overrides_from_different_assemblies
 {

src/FluentNHibernate/Automapping/AutoMapping.cs

@@ -42,24 +42,24 @@ void IAutoClasslike.AlterModel(ClassMappingBase mapping)
         if (mapping is ClassMapping classMapping)
         {
             if (providers.Id is not null)
-                classMapping.Set(x => x.Id, Layer.Defaults, providers.Id.GetIdentityMapping());
+                classMapping.Set(x => x.Id, Layer.UserSupplied, providers.Id.GetIdentityMapping());
 
             if (providers.NaturalId is not null)
-                classMapping.Set(x => x.NaturalId, Layer.Defaults, providers.NaturalId.GetNaturalIdMapping());
+                classMapping.Set(x => x.NaturalId, Layer.UserSupplied, providers.NaturalId.GetNaturalIdMapping());
 
             if (providers.CompositeId is not null)
-                classMapping.Set(x => x.Id, Layer.Defaults, providers.CompositeId.GetCompositeIdMapping());
+                classMapping.Set(x => x.Id, Layer.UserSupplied, providers.CompositeId.GetCompositeIdMapping());
 
             if (providers.Version is not null)
-                classMapping.Set(x => x.Version, Layer.Defaults, providers.Version.GetVersionMapping());
+                classMapping.Set(x => x.Version, Layer.UserSupplied, providers.Version.GetVersionMapping());
 
             if (providers.Discriminator is not null)
-                classMapping.Set(x => x.Discriminator, Layer.Defaults, providers.Discriminator.GetDiscriminatorMapping());
+                classMapping.Set(x => x.Discriminator, Layer.UserSupplied, providers.Discriminator.GetDiscriminatorMapping());
 
             if (Cache.IsDirty)
-                classMapping.Set(x => x.Cache, Layer.Defaults, ((ICacheMappingProvider)Cache).GetCacheMapping());
+                classMapping.Set(x => x.Cache, Layer.UserSupplied, ((ICacheMappingProvider)Cache).GetCacheMapping());
 
-            classMapping.Set(x => x.Tuplizer, Layer.Defaults, providers.TuplizerMapping);
+            classMapping.Set(x => x.Tuplizer, Layer.UserSupplied, providers.TuplizerMapping);
         }
 
         foreach (var join in providers.Joins)