#include <iostream>
#include <cstring>
#include <algorithm>
#include <cstdio>
#define int unsigned long long
using namespace std;
int a[1000005];
signed main(){
    int T; cin >> T;
    while (T --){
        int n; scanf("%lld", &n);
        for(int i = 1; i <= n; ++i) scanf("%lld", a + i);
        sort(a + 1, a + n + 1);
        int res = 0;
        for(int i = 1; i <= n; ++i){
            res += ((i << 1) - n - 1) * a[i];
        }
        printf("%lld\n", res);
    }
    return 0;
}