c# check if type implements interface

typeof(IMyInterface).IsAssignableFrom(typeof(MyType))
  // or
typeof(MyType).GetInterfaces().Contains(typeof(IMyInterface))
  // or for a generic interface, it’s a bit different:
typeof(MyType).GetInterfaces().Any(i => i.IsGenericType && i.GetGenericTypeDefinition() == typeof(IMyInterface<>)