Automatically register all Profiles's that can be located by using the ApplicationPartManager

AutoMapperExtensions.cs

using System;
using System.Collections.Generic;
using System.Linq;
using AutoMapper;
using Microsoft.AspNetCore.Mvc.ApplicationParts;

// ReSharper disable once CheckNamespace
namespace Microsoft.Extensions.DependencyInjection
{
    /// <summary>
    /// The auto mapper extensions.
    /// </summary>
    public static class AutoMapperExtensions
    {
        // https://github.com/aspnet/Mvc/pull/4391/commits/f638c051fa79c293ea7a0a859ed9700db9a18d71

        /// <summary>
        /// Automatically register all <see cref="Profile"/>'s that can be located by using the <see cref="ApplicationPartManager"/>
        /// </summary>
        /// <param name="services"></param>
        public static void UseAutoMapper(this IServiceCollection services)
        {
            services.AddSingleton(p => new MapperConfiguration(cfg => cfg.RegisterConfigurations(p.GetService<ApplicationPartManager>().ApplicationParts)));
            services.AddSingleton(p => p.GetService<MapperConfiguration>().CreateMapper());
        }

        private static void RegisterConfigurations(this IMapperConfigurationExpression config, IEnumerable<ApplicationPart> applicationParts)
        {
            if (applicationParts == null)
                throw new ArgumentNullException(nameof(applicationParts));

            applicationParts.OfType<AssemblyPart>()
                .SelectMany(p => p.Types)
                .Where(x => x.IsSubclassOf(typeof(Profile)))
                .Where(x => x.GetConstructor(Type.EmptyTypes) != null) // Make sure it has a default parameterless constructor
                .Select(Activator.CreateInstance)
                .OfType<Profile>()
                .ForEach(config.AddProfile);
        }
    }
}