verify(input) {
        if ([SATURDAY, SUNDAY].includes(this.dayOfWeek())) {
            throw new Error("It's the weekend!");
        }
        const errors = [];
        // 더 많은 코드가 여기에 있다.
        return errors;
    }
}

// stub-time/02-inject-object/password-verifier-time01.spec.js
describe('verifier', () => {
    test('class constructor: on weekends, throws exception', () => {
        const alwaysSunday = () => SUNDAY;
        const verifier = new PasswordVerifier([], alwaysSunday);
        expect(() => verifier.verify('anything'))
            .toThrow("It's the weekend!");
    });
});