public async Task Principal_nav_set_unidirectional_AddAsync()
        {
            using (var context = new FixupContext())
            {
                var principal = new ParentPN {
                    Id = 77
                };
                var dependent = new ChildPN {
                    Name = "1"
                };
                principal.Child1 = dependent;

                await context.AddAsync(principal);

                var entityState = EntityState.Added;

                Assert.Equal(2, context.ChangeTracker.Entries().Count());

                AssertFixup(
                    context,
                    () =>
                {
                    Assert.Equal(principal.Id, context.Entry(dependent).Property("ParentId").CurrentValue);
                    Assert.Same(dependent, principal.Child1);
                    Assert.Equal(entityState, context.Entry(principal).State);
                    Assert.Equal(entityState, context.Entry(dependent).State);
                });
            }
        }