test.go

package app

import (
	"fmt"
	"time"
)

type SessionClock interface {

	SessionDuration() time.Duration

}

type SessionRepository struct {
	clock SessionClock
}

type Session struct {
	Id             string
	ExpirationTime time.Time
}

func (s SessionRepository) UpdateSessionTime(sessionId string) Session {

	time := s.clock.SessionDuration()

	// load existing session from datastore (mongodb)
	session := Session{sessionId, time}

	// update time 
	session.UpdateExpirationTime(time)

	// store session in datastore

	return session
}

func (s Session) UpdateExpirationTime(time.Time time) bool{
	return s.ExpirationTime(time)
}

func (s SessionRepository) IsSessionExpired(sessionId string) bool {

}

type realClock struct{}

func (r realClock) Now() time.Time {
	return time.Now()
}

func DoSomething(clock Clock) {
	time := clock.Now()
	fmt.Printf("%s\n", time)
}