#include <cstdio>
#include <cstring>
#include <cmath>
#include <iostream>
#include <algorithm>
#include <vector>
#include <stack>
#include <sstream>
#include <map>
#include <set>
#include <string>
using namespace std;
typedef long long  ll;

ll s[100007],a[100007];
ll t,n,m,ans,num,sum,p;
int main()
{
    cin>>t;
    while(t--)
    {
        memset(s,0,sizeof(s));
        cin>>n;
        ans=0;
        for(int i=1;i<=n;i++)
        {
            scanf("%lld",&a[i]);
            
        }
        sort(a+1,a+1+n);
        for(int i=1;i<n;i++)
        {
            s[i]=a[i+1]-a[i];
            ans+=s[i]*(n-i)*i;
        }
        cout<<ans<<endl;
    }
}