#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <set>
#include <string>

using namespace std;

int main() {
    int t;
    cin >> t;
    while (t--) {
        int n;
        cin >> n;
        long long d[100005];
        for (int i = 0; i < n; i++) {
            scanf("%lld", d + i);
        }
        sort(d, d + n);
        long long res = 0;
        long long s = d[0];
        for (long long i = 1; i < n; i++) {
            res += d[i] * i - s;
            s += d[i];
        }
        cout << res << endl;
    }
    return 0;
}