Revert 3.0 fix for consistent reload and replace with fix that doesn'…

…t dramatically change detach behavior

Fixes #17784

In 3.0 we made a [simple change](7e65b82#diff-7767de8ee880eb46efbfc9d2153dd33a) for #15645 that started clearing navigation properties when they referenced detached entities. In retrospect this was the wrong thing to do as people are relying on this to be able to detach all entities from the context.

The new fix restores the pre-3.0 detach behavior, and sends the reload of a deleted entity through a simulated to delete instead.

src/EFCore/ChangeTracking/EntityEntry.cs

@@ -388,6 +388,7 @@ private void Reload(PropertyValues storeValues)
             {
                 if (State != EntityState.Added)
                 {
+                    State = EntityState.Deleted;
                     State = EntityState.Detached;
                 }
             }

src/EFCore/ChangeTracking/Internal/NavigationFixer.cs

@@ -511,7 +511,8 @@ public virtual void StateChanged(
                 {
                     InitialFixup(entry, fromQuery: false);
                 }
-                else if (entry.EntityState == EntityState.Detached)
+                else if (oldState == EntityState.Deleted
+                    && entry.EntityState == EntityState.Detached)
                 {
                     DeleteFixup(entry);
                 }

test/EFCore.Specification.Tests/GraphUpdatesTestBase.cs

@@ -836,7 +836,7 @@ public virtual void Detaching_principal_entity_will_remove_references_to_it()
         }
 
         [ConditionalFact]
-        public virtual void Detaching_dependent_entity_will_remove_references_to_it()
+        public virtual void Detaching_dependent_entity_will_not_remove_references_to_it()
         {
             ExecuteWithStrategyInTransaction(
                 context =>
@@ -944,26 +944,26 @@ public virtual void Detaching_dependent_entity_will_remove_references_to_it()
                     Assert.True(requiredChildrenAk.All(e => e.Parent == root));
                     Assert.True(requiredCompositeChildren.All(e => e.Parent == root));
 
-                    Assert.Null(root.OptionalSingle);
-                    Assert.Null(root.RequiredSingle);
-                    Assert.Null(root.OptionalSingleAk);
-                    Assert.Null(root.OptionalSingleDerived);
-                    Assert.Null(root.RequiredSingleAk);
-                    Assert.Null(root.OptionalSingleAkDerived);
-                    Assert.Null(root.OptionalSingleMoreDerived);
-                    Assert.Null(root.RequiredNonPkSingle);
-                    Assert.Null(root.OptionalSingleAkMoreDerived);
-                    Assert.Null(root.RequiredNonPkSingleAk);
-                    Assert.Null(root.RequiredNonPkSingleDerived);
-                    Assert.Null(root.RequiredNonPkSingleAkDerived);
-                    Assert.Null(root.RequiredNonPkSingleMoreDerived);
-                    Assert.Null(root.RequiredNonPkSingleAkMoreDerived);
-
-                    Assert.DoesNotContain(optionalChild, root.OptionalChildren);
-                    Assert.DoesNotContain(requiredChild, root.RequiredChildren);
-                    Assert.DoesNotContain(optionalChildAk, root.OptionalChildrenAk);
-                    Assert.DoesNotContain(requieredChildAk, root.RequiredChildrenAk);
-                    Assert.DoesNotContain(requiredCompositeChild, root.RequiredCompositeChildren);
+                    Assert.NotNull(root.OptionalSingle);
+                    Assert.NotNull(root.RequiredSingle);
+                    Assert.NotNull(root.OptionalSingleAk);
+                    Assert.NotNull(root.OptionalSingleDerived);
+                    Assert.NotNull(root.RequiredSingleAk);
+                    Assert.NotNull(root.OptionalSingleAkDerived);
+                    Assert.NotNull(root.OptionalSingleMoreDerived);
+                    Assert.NotNull(root.RequiredNonPkSingle);
+                    Assert.NotNull(root.OptionalSingleAkMoreDerived);
+                    Assert.NotNull(root.RequiredNonPkSingleAk);
+                    Assert.NotNull(root.RequiredNonPkSingleDerived);
+                    Assert.NotNull(root.RequiredNonPkSingleAkDerived);
+                    Assert.NotNull(root.RequiredNonPkSingleMoreDerived);
+                    Assert.NotNull(root.RequiredNonPkSingleAkMoreDerived);
+
+                    Assert.Contains(optionalChild, root.OptionalChildren);
+                    Assert.Contains(requiredChild, root.RequiredChildren);
+                    Assert.Contains(optionalChildAk, root.OptionalChildrenAk);
+                    Assert.Contains(requieredChildAk, root.RequiredChildrenAk);
+                    Assert.Contains(requiredCompositeChild, root.RequiredCompositeChildren);
                 });
         }
 

test/EFCore.Specification.Tests/PropertyValuesTestBase.cs

@@ -1301,7 +1301,9 @@ public async Task Reload_when_entity_deleted_in_store_can_happen_for_any_state(E
                 {
                     Assert.Equal(EntityState.Detached, entry.State);
                     Assert.Null(mailRoom.Building);
-                    Assert.Same(state == EntityState.Deleted ? building : null, office.Building);
+
+                    Assert.Equal(EntityState.Detached, context.Entry(office.Building).State);
+                    Assert.Same(building, office.Building);
                 }
 
                 Assert.Same(mailRoom, building.PrincipalMailRoom);

test/EFCore.Specification.Tests/ProxyGraphUpdatesTestBase.cs

@@ -682,7 +682,7 @@ public virtual void Save_required_one_to_one_changed_by_reference(ChangeMechanis
                     Assert.Same(root, new1.Root);
                     Assert.Same(new1, new2.Back);
 
-                    Assert.Null(old1.Root);
+                    Assert.NotNull(old1.Root);
                     Assert.Null(old2.Back);
                     Assert.Equal(old1.Id, old2.Id);
                 });