Wrap Method version 2 example

Employee.ts

// We also want to keep the original behavior (paying without logging)

//////////////////////////////////////////////////
// Step 1: Identify the change point

export class Employee {
    public timeCards: TimeCard[];
    public payPeriod: Date[];
    public date: Date;
    public payRate: number;
    public payDispatcher: PayDispatcher;

    public pay(): void {
        const amount = new Money();
        for (const card of this.timeCards) {
            if (this.payPeriod.includes(this.date)) {
                amount.add(card.hours * this.payRate);
            }
        }
        this.payDispatcher.pay(this, this.date, amount);
        // <-- this is the change point
    }
}

//////////////////////////////////////////////////
// Step 2: Develop a method for the new behaviour with tests, (logPayment in this case)

export class Employee {
    // rest of the code omitted for the sake of brevity...

    public logPayment(logger: Logger): void {
        // code for log payment
    }
}

//////////////////////////////////////////////////
// Step 3: Create a new pubic method for the cpmposed behaviour, (makeLoggedPayment in this case)

export class Employee {
    // rest of the code omitted for the sake of brevity...

    public makeLoggedPayment(): void { // <- new method composing old and new behaviors
        this.pay();
        this.logPayment(logger);
    }

    public pay(): void {
        const amount = new Money();
        for (const card of this.timeCards) {
            if (this.payPeriod.includes(this.date)) {
                amount.add(card.hours * this.payRate);
            }
        }
        this.payDispatcher.pay(this, this.date, amount);
    }

    public logPayment(logger: Logger): void {
        // log employee data
    }
}