class-interface-implements.ts

interface SizesInterface {
  availableSizes: string[];
}

abstract class Sizes implements SizesInterface {
  constructor(protected sizes: string[]) {}

  set availableSizes(sizes: string[]) {
    this.sizes = sizes;
  }

  get availableSizes() {
    return this.sizes;
  }
}

interface PizzaInterface extends SizesInterface {   
  readonly name: string;
  toppings: string[];
  updateSizes(sizes: string[]): void;
  addTopping(topping: string): void;
}

class Pizza extends Sizes implements PizzaInterface {
  public toppings: string[] = [];

  constructor(readonly name: string, sizes: string[]) {
    super(sizes);
  }

  public updateSizes(sizes: string[]) {
    this.sizes = sizes;
  }

  public addTopping(topping: string) {
    this.toppings.push(topping);
  }
}

const pizza = new Pizza("Puuporrroni", ["small", "medium"]);

console.log(pizza.availableSizes);

pizza.updateSizes(["large", "ultimate"]);

console.log(pizza.availableSizes);