#include<bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> PII;

const int MAXN = 1e6 + 10;
const int MM = 1e9 + 7;

int n;
ll a[MAXN];

void solve(int casi){
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) {
        scanf("%lld", &a[i]);
    }
    sort(a + 1, a + n + 1);
    ll sm = a[1];
    ll ans = 0;
    for (int i = 2; i <= n; i++) {
        ans += (i - 1) * a[i] - sm;
        sm += a[i];
    }
    printf("%lld\n", ans);
}

int main(){
    int T = 1;
    scanf("%d", &T);
    for (int i = 1; i <= T; i++)
        solve(i);
    return 0;
}