Simple C# program that uses Caste DynamicProxy intereception

Caste_DynamicProxy_interceptor.cs

// requires:
// dotnet add package Castle.Core --version 4.4.0
// output:
// IAdder::Sum invoked
// 3

using System.Runtime.CompilerServices;
using System;
using Castle.DynamicProxy;

[assembly: InternalsVisibleTo("DynamicProxyGenAssembly2")]

interface IAdder
{
    int Sum(int a, int b);
}

class Adder : IAdder
{
    public int Sum(int a, int b) { return a + b; }
}

public class Interceptor : IInterceptor
{
  public void Intercept(IInvocation invocation)
  {
      if (invocation.Method.Name.Equals("Sum")) {
          Console.WriteLine("IAdder::Sum invoked");
      }
      invocation.Proceed();
  }
}

class Program
{
    static void Main(string[] args)
    {
        IAdder adder = new Adder();
        var proxy = new ProxyGenerator().CreateInterfaceProxyWithTarget(adder, new Interceptor());

        var result = proxy.Sum(1, 2);

        Console.WriteLine($"{result}");
    }
}