#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
using namespace std;

const int MaxN = 100000;
int T, n, a[MaxN + 5];
long long suff[MaxN + 5];

int main()
{
    scanf("%d", &T);
    for (int cas = 1; cas <= T; cas++) {
        scanf("%d", &n);
        for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
        sort(a + 1, a + n + 1);
        suff[n + 1] = 0;
        for (int i = n; i >= 1; i--) {
            suff[i] = suff[i + 1] + a[i];
            //cout << suff[i] << endl;
        }
        long long ans = 0;
        for (int i = 1; i <= n - 1; i++) {
            ans = (ans + suff[i + 1] - (long long)a[i] * (n - i));
        }
        printf("%lld\n", ans);
    }
    return 0;
}