Test if object implements interface

if (object is IBlah)

IBlah myTest = originalObject as IBlah

if (myTest != null)

if( typeof(IMyInterface).IsAssignableFrom(someOtherType) )
{
}

if (obj is IMyInterface) {}

public static void BubbleSort<T>(ref IList<T> unsorted_list) where T : IComparable
{
     //Some bubbly sorting
}

MyInstace.GetType().GetInterfaces();

if (obj is IMyInterface)

if (obj.GetType() == typeof(IMyInterface))