#include <cstdio>
#include <iostream>
#include <algorithm>
using namespace std;

const int N = 100005;

int n, a[N];

typedef long long LL;

LL ans, sum[N];

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