Sample AM

AutoMapper.cs

using AutoMapper;

interface IDestination
{
    int SomeProp { get; }
}

class Destination : IDestination
{
    public int SomeProp { get; set; }
}

class Source 
{
    public int SomeOther { get; set; } = 42;
}

class Program
{
    static void Main()
    {
        var configurationNotMapped = new MapperConfiguration(cfg => 
        {
            cfg.CreateMap<Source, IDestination>()
                .ForMember(d => d.SomeProp, o => o.MapFrom(s => s.SomeOther));

            cfg.CreateMap<Source, Destination>()
                .IncludeBase<Source, IDestination>();
        });

        var configurationMapped = new MapperConfiguration(cfg => 
        {
            cfg.CreateMap<Source, IDestination>()
                .ForMember(d => d.SomeProp, o => o.MapFrom(s => s.SomeOther));

            cfg.CreateMap<Source, Destination>()
                // any mention of target property, 
                // for example .ForMember(d => d.SomeProp, o => o.ExplicitExpansion())
                .ForMember(d => d.SomeProp, o => {})
                .IncludeBase<Source, IDestination>();
        });

        configurationNotMapped.AssertConfigurationIsValid();
        configurationMapped.AssertConfigurationIsValid();

        var source = new Source();

        // will output 0
        Console.WriteLine(configurationNotMapped.CreateMapper()
            .Map<Destination>(source).SomeProp);
        
        // will output 42
        Console.WriteLine(configurationMapped.CreateMapper()
            .Map<Destination>(source).SomeProp);
    }
}