#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <queue>
using namespace std;

const double eps = 1e-8;

long long a[100005];

int main(){
    int t;
    int n;
    scanf("%d",&t);
    while(t--){
        scanf("%d",&n);
        for(int i = 1;i <= n; ++i){
            scanf("%lld",&a[i]);
        }
        sort(a + 1, a + n + 1);
        long long res = 0;
        for(int i = 2;i <= n; ++i){
            res += (a[i] - a[i - 1]) * (i - 1) * (n - i + 1);
        }
        printf("%lld\n",res);
    }
    
}