#include <bits/stdc++.h>

using namespace std;

int T, n, a[100000];
unsigned long long ans, sum;

int main() {
  scanf("%d", &T);
  while (T--) {
    scanf("%d", &n);
    for (int i = 0; i < n; ++i) scanf("%d", &a[i]);
    sort(a, a + n);
    ans = sum = 0;
    for (int i = 0; i < n; ++i) {
      ans += (unsigned long long)a[i] * i - sum;
      sum += a[i];
    }
    printf("%llu\n", ans);
  }
  return 0;
}