Easy mocking with Mock Generic function (Typescipt)

mock.ts

class Person{	
	private Name: string;
	constructor(public Age: number, name: string){
		this.Name = name;
	}
	Older(){
		this.Age ++;
	}
}

class Student extends Person{	
	constructor(public Age: number,public StudentNumber: number, name: string){
		super(Age,name);
	}
	Older(){
		this.Age ++;
	}	
	Younger(){
		this.Age --;
	}
}

class PersonSpec implements Mocker.ITestable<PersonSpec,Person>{
	Mock = new Mocker.Mock<Person>(Person);
	P: Person;
	S: Student;
	constructor() {			
		this.P = this.Mock
			.With(x => x.Age = 4)
			.Private(x => x.Name = "s")
			.Create();
		
		//Tests
		console.log(P.Age); //4
		P.Older();
		console.log(P.Age); //5
	}
}

module Mocker {
	export interface ITestable<SpecClass,Subject>{
		Mock: Mocker.Mock<Subject>;
	}
	export class Mock<T>{	
		//pass in the 'type' 
		//'type' is actually a function
		private CreatedType: T;
		constructor(private Type: any){}
		
		public With(mutator: (obj:T)=>void): Mock<T>{
			//avoid compile time error as type is any. 
			//any can have 0 param constructor
			var t = new this.Type();
			//set reference to newly created type
			this.CreatedType = t;
			//pass it into the passed in function
			mutator(t);
			return this;
		}
		
		//lose type safety because of private members
		public Private(mutator: (obj: any)=>void): Mock<T>{
			if(!this.CreatedType){
				var t = new this.Type();
				this.CreatedType = t;
			}
			mutator(t);
			return this;
		}
		
		public Create(): T{
			return this.CreatedType
		}
	}	
}