#include <bits/stdc++.h>
#include <string>
#include <algorithm>
#include <vector>
#include <string.h>
#include <stdlib.h>
#include <chrono>
#include <ctime>
using namespace std;
using namespace std::chrono;
typedef long long ll;
#define fast ios_base::sync_with_stdio(false); cin.tie(nullptr)
#define all(v) v.begin(), v.end()
#define vi vector<int>
const int N = 2e6;

void solve() {
        int a[N];
		long long n;
		cin >> n;
		for (int i = 0; i < n ; i ++) cin >> a[i];
		sort(a, a + n);
		long long rlt = a[n - 1];
		for (long long i = 1; i < n; i ++) {
			long long v = a[i] - a[i - 1];
			rlt -= v * i * (n - i);
		}
		cout << rlt << endl;
}

int main() {
	fast;
   int t; cin >> t;
   while (t--)solve();
}
