/**********************************************
 *Author*        :jxf378440404
 *Created Time*  : 2020/7/25 14:39:23

*********************************************/

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <map>
#include <queue>
#include <set>
#define fi first
#define se second
#define ls now << 1
#define rs now << 1 | 1
using namespace std;
typedef long long LL;
typedef pair<int, int> PII;
const int MaxN = 1e5;
const int Inf = 1 << 30;
const LL mod = 998244353;
inline int lowbit(int x) { return x & -x; }

LL a[MaxN + 5];

int main()
{
    int T; scanf("%d", &T);
    while(T--) {
        int n; LL ans = 0, sum = 0;
        scanf("%d", &n);
        for(int i = 0; i < n; ++i) scanf("%lld", &a[i]);
        sort(a, a + n);
        for(int i = 0; i < n; ++i) {
            ans += a[i] * i - sum;
            sum += a[i];
        }
        printf("%lld\n", ans);
    }
    return 0;
}