beforeTimeVal := time.Now()
	beforeTimeMap := map[string]interface{}{"ts": beforeTimeVal}
	before, err := Marshal(beforeTimeMap)
	noerr(t, err)

	afterTimeMap := map[string]interface{}{}
	err = Unmarshal(before, &afterTimeMap)
	noerr(t, err)
	afterTime, ok := afterTimeMap["ts"].(time.Time)
	if !ok {
		t.Errorf("after time format error. after time info:%#v", afterTimeMap)
		return
	}
	if afterTime.UnixNano() != beforeTimeVal.UnixNano() {
		t.Errorf("after time not equal before time. befere:%#v, after:%#v", beforeTimeVal, afterTime)
		return
	}

/home/reage/go_src/src/mongodb/mongo-go-driver/bson/bson_test.go:67: after time format error. after time info:map[string]interface {}{"ts":1560433311128}
FAIL