#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long LL;
const int N = 1E5 + 5;;
int n;
LL a[N];
void solve() {
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) scanf("%llu", &a[i]);
    sort(a + 1, a + n + 1);
    LL sum = 0, ans = 0;
    for (int i = 1; i <= n; i++) {
        ans += a[i] * (i - 1) - sum;
        sum += a[i];
    }
    cout << ans << endl;
}
int main() {
    int T;
    cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}