#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
#define ll long long
#define ge getchar 
#define pun putchar('\n')
#define pu putchar
#define puk putchar(' ')
char c;
int tt,n,i;
ll a[100008],s,cx,g[50];
int sri(){c=ge();int x=0;while(c<'0')c=ge();while(c>='0')x=(x<<3)+(x<<1)+c-'0',c=ge();return x;}
void sc(ll x){int l=0;if(x==0)g[l=1]=0;while(x)g[++l]=x%10,x/=10;for(;l;l--)putchar(g[l]+'0');}
int main(){
    tt=sri();
    while(tt--){
        n=sri();
        for(i=1;i<=n;i++)a[i]=(ll)sri();
        sort(a+1,a+n+1);cx=0;s=a[1];
        for(i=1;i<n;i++){
            cx+=i*a[i+1]-s;s+=a[i+1];
        }sc(cx);pun;
    }
    return 0;
}