#include <bits/stdc++.h>
using namespace std;
#define int long long
#define si signed
#define sc(x) scanf("%lld",&(x));
#define fi first
#define se second
#define pb push_back
#define P pair<int,int>
#define endl '\n'
int a[100000];
si main() {
    int T;
    sc(T)
    int n,m,p;
    while(T--){
        sc(n)
        for(int i=0;i<n;i++){
            sc(a[i])
        }
       sort(a,a+n);
        int ans = 0;
        int p = a[0];
        for(int i=1;i < n;i++){
            ans = ans+(i)*a[i]-p;
            p+= a[i];
           // cout<<ans<<'\n';
        }
        cout<<ans<<'\n';
    }

    return 0;
}