#include<iostream>
#include<stdio.h>
#include<math.h>
#include<string>
#include<string.h>
#include<algorithm>
#include<vector>
using namespace std;
#define ll long long 
const int maxn = 1e5+10;
ll ans;
int n;
ll a[maxn];
int main()
{
    int t; scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        for(int i=1;i<=n;i++) scanf("%lld",&a[i]);
        sort(a+1,a+1+n);
        ans=0;
        for(int i=2;i<=n;i++)
        {
            ans+=(ll)(i-1)*a[i]-a[i-1];
            a[i]+=a[i-1];
        }
        printf("%lld\n",ans);
    }
    return 0;
}