#include<bits/stdc++.h>

using namespace std;
#define ll long long

const int N = 100005;
int T, n, a[N];
int main() {
    scanf("%d", &T);
    while(T--){
        scanf("%d", &n);
        for(int i=1; i<=n; ++i) scanf("%d", a+i);
        sort(a+1, a+n+1);
        ll x=0, y=0, ans=0;
        for(int i=1; i<=n; ++i) ans+=a[i]*y-x, x+=a[i], ++y;
        printf("%lld\n", ans);
    }
    return 0;
}