#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

typedef long long ll;

ll A[100010];

void Solve() {
    int n;
    scanf("%d", &n);
    for(int i = 1; i <= n; i++) scanf("%lld", &A[i]);
    sort(A + 1, A + n + 1);
    ll ans = 0;
    for(int i = 1; i < n; i++) {
        ll delta = A[i + 1] - A[i], l = i, r = n - i;
        ans += l * r * delta;
    }
    printf("%lld\n", ans);
}
int main() {
    int test;
    scanf("%d", &test);
    while(test--) {
        Solve();
    }
}