const (
	minUserID  = 0
	maxUserID  = math.MaxInt32
	minGroupID = 0
	maxGroupID = math.MaxInt32
)

// IsValidGroupID tests that the argument is a valid Unix GID.
func IsValidGroupID(gid int64) []string {
	if minGroupID <= gid && gid <= maxGroupID {
		return nil
	}
	return []string{InclusiveRangeError(minGroupID, maxGroupID)}
}

	goodValues := createGroupIDs(0, 1, 1000, 65535, 2147483647)
	for _, val := range goodValues {
		if msgs := IsValidGroupID(val); len(msgs) != 0 {
			t.Errorf("expected true for '%d': %v", val, msgs)
		}
	}

	badValues := createGroupIDs(-1, -1003, 2147483648, 4147483647)
	for _, val := range badValues {
		if msgs := IsValidGroupID(val); len(msgs) == 0 {
			t.Errorf("expected false for '%d'", val)
		}
	}
}