InvoiceAfter.ts

// After changing the code, Invoice should look like:

export class Invoice {
    private readonly shippingPricer: ShippingPricer;
    // ...

    constructor(
        billingDate: OurDate,
        openingDate: OurDate,
        originator: Originator,
        // ...
    ) {
        // ...
        this.shippingPricer = new ShippingPricer(billingDate, openingDate, originator);
    }

    // ...

    public getValue(): Money {
        const total = this.itemsSum();
        total.add(this.shippingPricer.getPrice());
        total.add(this.getTax());
        return total;
    }

    private itemsSum(): Money {
        throw new Error("Not implemented");
    }

    // ...
}