#include <bits/stdc++.h>
#define all(n) (n).begin(), (n).end()
#define se second
#define fi first
#define pb push_back
#define mp make_pair
#define sqr(n) (n)*(n)
#define rep(i,a,b) for(int i=(a);i<=(b);++i)
#define per(i,a,b) for(int i=(a);i>=(b);--i)
#define IO ios::sync_with_stdio(0); cin.tie(0);
using namespace std;
typedef long long ll;
typedef pair<int, int> PII;
typedef pair<ll, ll> PLL;
typedef vector<int> VI;
typedef double db;

const int N = 1e5 + 5;

int n, m, _, k;
int a[N];

int main() {
    IO;
    for (cin >> _; _; --_) {
        cin >> n;

        rep (i, 1, n) cin >> a[i];
        sort(a + 1, a + 1 + n);

        ll ans = 0;
        rep (i, 2, n) {
            ans += (ll)(a[i] - a[i - 1]) * (n - i + 1) * (i - 1);
        }

        cout << ans << '\n';
    }
    return 0;
}