An in-memory implementation of persistence mechanism

in-memory-product-repository.ts

interface ProductRepository {
  save(product: Product): Promise<void>;

  load(id: ProductId): Promise<Product | null>;
}

export default class InMemoryProductRepository implements ProductRepository {
  private products = new Map<string, Product>();

  async save(product: Product) {
    this.products.set(product.id.toString(), product);
  }

  async load(id: ProductId): Promise<Product | null> {
    return this.products.get(id.toString()) || null;
  }
}