#include <algorithm>
#include <cstdio>
#include <cstring>
#include <iostream>
#define ll long long
using namespace std;

const int N = 1e5 + 10;

int T;
int n;
ll a[N];

int main() {
    cin >> T;
    while (T--) {
        scanf("%d", &n);
        ll res = 0;
        for (int i = 0; i < n; i++) {
            scanf("%lld", &a[i]);
        }
        sort(a, a + n);
        for (int i = 1; i < n; i++) {
            res += (1ll * (n - i) * i * (a[i] - a[i - 1]));
        }
        printf("%lld\n", res);
    }

    return 0;
}