#include <bits/stdc++.h>
using namespace std;

int t, n, a[100005];
int main() {
    cin >> t;
    while(t--) {
        cin >> n;
        long long l = 0, r = 0, ans = 0;
        for(int i = 0; i < n; i++) scanf("%d", a + i), r += a[i];
        sort(a, a + n);
        for(long long i = 0; i < n; i++) {
            r -= a[i];
            if(i) l += a[i - 1];
            ans += r - (n - 1 - i) * a[i] + i * a[i] - l;
        }
        cout << ans / 2 << endl;
    }
}