Wrap Method V1 example

Employee.ts

//////////////////////////////////////////////////
// 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: Extract a method with the body of the current method

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

    public pay(): void {
        this.dispatchPayment();
        // <-- this is the change point
    }

    private dispatchPayment(): 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);
    }
}


//////////////////////////////////////////////////
// Step 3: Develop a method for the new behaviour with tests

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

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

////////////////////////////////////////////////////
// Step 4: Call it from the current method

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

    public pay(): void {
        this.dispatchPayment();
        this.logPayment(new AcmeLogger()); // <-- call to the new method
    }

    private dispatchPayment(): void {
        // rest of the code omitted for brevity...
    }

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