Optional dependent null

test/EFCore.Relational.Specification.Tests/TableSplittingTestBase.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Linq;
 using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore.TestModels.QueryModel;
 using Microsoft.EntityFrameworkCore.TestModels.TransportationModel;
 using Microsoft.EntityFrameworkCore.TestUtilities;
 using Xunit;
@@ -548,6 +549,48 @@ public virtual async Task Optional_dependent_materialized_when_no_properties()
             }
         }
 
+        [ConditionalFact]
+        public virtual async Task Warn_When_Save_Optional_dependent_with_null_values()
+        {
+            await InitializeAsync(
+                modelBuilder =>
+                {
+                    modelBuilder.Entity<MeterReadingDetails>(
+                        dob =>
+                        {
+                            dob.ToTable("MeterReadings");
+                            dob.Property(o => o.ReadingStatus).HasColumnName("ReadingStatus");
+                        });
+
+                    modelBuilder.Entity<MeterReading>(
+                        ob =>
+                        {
+                            ob.ToTable("MeterReadings");
+                            ob.Property(o => o.ReadingStatus).HasColumnName("ReadingStatus");
+                            ob.HasOne(o => o.MeterReadingDetails).WithOne()
+                                .HasForeignKey<MeterReadingDetails>(o => o.Id);
+                        });
+                }
+                );
+
+            using (var context = CreateContext())
+            {
+                var scooterEntry = context.Add(
+                    new MeterReading
+                    {
+                        MeterReadingDetails = new MeterReadingDetails()
+                    });
+
+                context.SaveChanges();
+            }
+
+            using (var context = CreateContext())
+            {
+                var reading = context.Set<MeterReading>().Include(o => o.MeterReadingDetails).OrderBy(o => o.Id).First();
+                Assert.Null(reading.MeterReadingDetails);
+            }
+        }
+
         protected override string StoreName { get; } = "TableSplittingTest";
         protected TestSqlLoggerFactory TestSqlLoggerFactory
             => (TestSqlLoggerFactory)ListLoggerFactory;

test/EFCore.Specification.Tests/TestModels/QueryModel/MeterReading.cs

@@ -0,0 +1,12 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.EntityFrameworkCore.TestModels.QueryModel
+{
+    public class MeterReading
+    {
+        public int Id { get; set; }
+        public MeterReadingStatus? ReadingStatus { get; set; }
+        public MeterReadingDetails MeterReadingDetails { get; set; }
+    }
+}

test/EFCore.Specification.Tests/TestModels/QueryModel/MeterReadingDetails.cs

@@ -0,0 +1,13 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.EntityFrameworkCore.TestModels.QueryModel
+{
+    public class MeterReadingDetails
+    {
+        public int Id { get; set; }
+        public MeterReadingStatus? ReadingStatus { get; set; }
+        public string CurrentRead { get; set; }
+        public string PreviousRead { get; set; }
+    }
+}

test/EFCore.Specification.Tests/TestModels/QueryModel/MeterReadingStatus.cs

@@ -0,0 +1,11 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.EntityFrameworkCore.TestModels.QueryModel
+{
+    public enum MeterReadingStatus
+    {
+        Running=0,
+        NotAccesible=2
+    }
+}