ServiceCollectionExtensions.cs

using System;
using System.Linq;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyInjection.Extensions;

namespace Workbench.DependencyInjection.Extensions;

public static class ServiceCollectionExtensions
{
    public static IServiceCollection Decorate<TInterface, TDecorator>(this IServiceCollection services)
       where TInterface : class
       where TDecorator : class, TInterface
    {
        ServiceDescriptor innerDescriptor = services.FirstOrDefault(s => s.ServiceType == typeof(TInterface));

        if (innerDescriptor == null) { throw new InvalidOperationException($"{typeof(TInterface).Name} is not registered"); }

        var objectFactory = ActivatorUtilities.CreateFactory(
          typeof(TDecorator),
          new[] { typeof(TInterface) });

        services.Replace(ServiceDescriptor.Describe(
          typeof(TInterface),
          s => (TInterface)objectFactory(s, new[] { s.CreateInstance(innerDescriptor) }), innerDescriptor.Lifetime)
        );

        return services;
    }

    private static object CreateInstance(this IServiceProvider services, ServiceDescriptor descriptor)
    {
        if (descriptor.ImplementationInstance != null)
        {
            return descriptor.ImplementationInstance;
        }

        if (descriptor.ImplementationFactory != null)
        {
            return descriptor.ImplementationFactory(services);
        }

        return ActivatorUtilities.GetServiceOrCreateInstance(services, descriptor.ImplementationType);
    }

}