#include<bits/stdc++.h>

using namespace std;
const int M=100005;
int n,a[M];
long long ans;
void solve(){
    scanf("%d",&n);
    for(int i=1;i<=n;++i)scanf("%d",&a[i]);
    sort(a+1,a+n+1);ans=0;
    for(int i=1;i<n;++i){
        int d=a[i+1]-a[i];
        ans+=1ll*d*i*(n-i);
    }
    printf("%lld\n",ans);
}
int main(){
    int t;scanf("%d",&t);
    for(;t;--t)solve();
    return 0;
}