public class User 
{
    public DateTime? Birthday { get; set; }
}

public class FakeUserForCreationDto : AutoFaker<UserForCreationDto>
{
}

    [Test]
    public async Task can_update_user()
    {
        // Arrange
        var fakeUserOne = User.Generate(new FakeUserForCreationDto()
            .Generate());
        var updatedUserDto = new FakeUserUpdateDto()
            .Generate();
        await InsertAsync(fakeUserOne);

        var user = await ExecuteDbContextAsync(db => db.Users.SingleOrDefaultAsync());
        var id = user.Id;

        // Act
        var command = new UpdateUser.UpdateUserCommand(id, updatedUserDto);
        await SendAsync(command);
        var updatedUser = await ExecuteDbContextAsync(db => db.Users.Where(d => d.Id == id).SingleOrDefaultAsync());

        // Assert
        updatedUser.Should().BeEquivalentTo(updatedUserDto, options =>
            options.ExcludingMissingMembers());
    }

public class FakeUserForCreationDto : AutoFaker<UserForCreationDto>
{
    public FakeUserForCreationDto(Guid? userId = null)
    {
        RuleFor(u => u.Birthday, f => f.Date.Past().ToUniversalTime());
    }
}

AutoFaker.Configure(builder =>
{
  builder
    .WithDateTimeKind(DateTimeKind.Utc)  // Configures dates to be generated with a given DateTimeKind. Defaults to `Local`

    .WithLocale()         	// Configures the locale to use
    .WithRepeatCount()    	// Configures the number of items in a collection
    .WithDataTableRowCount()	// Configures the number of data table rows to generate
    .WithRecursiveDepth() 	// Configures how deep nested types should recurse
    .WithTreeDepth()		// Configures the tree depth of an object graph
    .WithBinder()         	// Configures the binder to use
    .WithFakerHub()       	// Configures a Bogus.Faker instance to be used - instead of a default instance
    .WithSkip()           	// Configures members to be skipped for a type
    .WithOverride();      	// Configures the generator overrides to use - can be called multiple times
});