#include<bits/stdc++.h>
#define N 100005
#define LL long long
#define Ms(a,b) memset(a,b) memset(a,b,sizeof a)
#define db(x) cerr<<#x<<"="<<x<<endl;
#define db2(x,y) cerr<<#x<<"="<<x<<" "<<#y<<"="<<y<<endl;
#define db3(x,y,z) cerr<<#x<<"="<<x<<" "<<#y<<"="<<y<<" "<<#z<<"="<<z<<endl;
using namespace std;
int T,n,a[N];
int main(){
    scanf("%d",&T);
    while(T--){
        scanf("%d",&n);
        for(int i=1;i<=n;i++)scanf("%d",&a[i]);
        LL s=0,res=0;
        sort(a+1,a+1+n);
        for(int i=1;i<=n;i++)res+=1ll*a[i]*(i-1)-s,s+=a[i];
        printf("%lld\n",res);
    }
    return 0;
}