[Unit Testing] Jasmine Spies

it ('should add two numbers', () => {
    
    const logger = jasmine.createSpyObj('LoggerService', ['log'])
    // logger.log.and.returnValue();
　　 const calculator = new CalculatorService(logger)
    const result = calculator.add(2,2)
    expect(result).toBe(4)
    expect(logger).toHaveBeenCalledTimes(1)

})