//Δ_1002
#include<iostream>
#include<cstdio>
#include<fstream>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<bitset>
#include<cmath>
#include<cstring>
#include<cstdlib>
using namespace std;
typedef long long LL;
typedef double DB;
const int N = 111111;
int n,a[N];
LL s;
int main()
{
    int T,i;
    scanf("%d",&T);
    while(T--){
        scanf("%d",&n);
        for(i=1;i<=n;i=i+1)
            scanf("%d",a+i);
        sort(a+1,a+n+1);
        s=0;
        for(i=1;i<n;i=i+1)
            s+=(LL)(a[i+1]-a[i])*i*(n-i);
        cout<<s<<endl;
    }
    return 0;
}