#include<iostream>
#include<sstream>
#include<cstdio>
#include<cstdlib>
#include<string>
#include<cstring>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<numeric>
#include<cmath>
#include<queue>
#include<vector>
#include<set>
#include<cctype>
#include<stack>
#include<map>
typedef long long ll;
const double PI = acos(-1.0);
const int INF = 0x3f3f3f3f;
const int NINF = -INF - 1;
const int maxn = 1e5 + 10;
const double eps = 1e-9;
const int mod = 1e9 + 9;
using namespace std;
ll a[maxn], sum[maxn];
int main()
{
    int T;
    cin >> T;
    while(T--){
        int n;
        scanf("%d", &n);
        for(int i = 0; i < n; ++i) scanf("%lld", &a[i]);
        sort(a, a + n);
        sum[n - 1] = a[n - 1];
        for(int i = n - 2; i >= 0; --i) sum[i] = sum[i + 1] + a[i];
//        for(int i = 0; i < n; ++i) cout << sum[i] << ' ';
//        cout << endl;
        ll ans = 0;
        for(int i = 0; i < n - 1; ++i){
            ans += sum[i + 1] - (n - 1 - i) * a[i];
        }
        printf("%lld\n", ans);
    }
    return 0;
}