Example of delegating service registration to a method in another assembly

ServiceConfiguration.cs

public static class ServiceConfiguration
{
	public static void ConfigureServices(IServiceCollection services, IMvcBuilder mvcBuilder)
	{
		services.AddTransient(provider => new ValidatorActionFilter());

		mvcBuilder.AddMvcOptions(o => o.Filters.AddService<ValidatorActionFilter>());
			

		mvcBuilder.AddFluentValidation(fvc => fvc.RegisterValidatorsFromAssemblyContaining<PersonValidation>());

		services.AddSingleton<IEnglishHello, EnglishHello>();
		services.AddSingleton<IFrenchHello, FrenchHello>();
		services.AddSingleton<IEnglishInformalHello, EnglishInformalHello>();
		services.AddSingleton<ISayHelloLanguage>(provider => provider.GetService<IEnglishHello>());
		services.AddSingleton<ISayHelloLanguage>(provider => provider.GetService<IFrenchHello>());
		services.AddSingleton<ISayHello>(provider => provider.GetService<IEnglishHello>());
		services.AddSingleton<ISayHello>(provider => provider.GetService<IFrenchHello>());
		services.AddSingleton<ISayHello>(provider => provider.GetService<IEnglishInformalHello>());
		services.AddSingleton<ISayHelloFactory>(provider =>
			new SayHelloFactory(provider.GetService<IEnumerable<ISayHello>>()));           
	}

	public static IServiceProvider BuildAlternativeServiceProvider(this IServiceCollection services)
	{
		var builder = new ContainerBuilder();
		builder.Populate(services);
		return new AutofacServiceProvider(builder.Build());
	}
}