gistfile1.cs

using System;
using System.Reflection;
using PostSharp.Aspects;
using PostSharp.Extensibility;
using NUnit.Framework;

namespace Examples
{
    public interface IServiceWithDependency
    {
        int SomeValue { get; set; }
    }

    [Serializable]
    public class InjectedAspectAttribute : MethodInterceptionAspect
    {
        public override bool CompileTimeValidate(MethodBase method)
        {
            var result = true;
            var methodInfo = method as MethodInfo;

            if (!typeof(IServiceWithDependency).IsAssignableFrom(method.DeclaringType))
            {
                Message.Write(methodInfo, SeverityType.Error, "999", string.Format("Only class derived from IServiceWithDependency allowed, {0} not implements IServiceWithDependency", method.DeclaringType));

                result = false;
            }

            return result;
        }

        public override void OnInvoke(MethodInterceptionArgs args)
        {
            if (args.Instance is IServiceWithDependency)
            {
                (args.Instance as IServiceWithDependency).SomeValue = 123;
            }

            args.Proceed();
        }
    }
    
    [TestFixture]
    public class InjectedAspectTests
    {    
        [Test]
        public void InjectedAspect_Dependency_Should456123()
        {
            // Arrange
            var sut = new MyClass();

            // Act
            var result = sut.DoSomething();

            // Assert
            Assert.That(result, Is.EqualTo("456123"));
        }

        public class MyClass : IServiceWithDependency
        {
            public int SomeValue { get; set; }

            [InjectedAspect]
            public string DoSomething()
            {
                string otherValue = "456" + SomeValue;

                return otherValue;
            }
        }

    }
}