#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <cmath>
#include <set>
#include <vector>
#include <utility>
#include <stack>
#include <deque>
#include <queue>
#include <string>
#include <cctype>
#include <ctime>
#include <sstream>
#include <map>
//#define LOCAL
#define ll long long
#define maxn 100010
#define maxw 1000005
#define INF 1000000000000000000
using namespace std;

int n;
ll a[maxn];

int main()
{
#ifdef LOCAL
    freopen("data.in.txt", "r", stdin);
    freopen("data.out.txt", "w", stdout);
#endif
    int t; cin >> t;
    while(t--)
    {
        cin >> n;
        for(int i = 0; i < n; i++)
            scanf("%lld", &a[i]);
        sort(a, a+n);
        ll ans = 0;
        for(ll i = 1; i <= n-1; i++)
            ans += i * (n-i) * (a[i] - a[i-1]);
        printf("%lld\n", ans);
    }
    return 0;
}