#include <vector>
#include <string>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <queue>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <fstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <cctype>
#include <ctime>

using namespace std;

long long int a[200000],dis[200000];

int main()
{
    long long test,i1,n,i;
    long long ans;
    cin>>test;
    for (i1=1;i1<=test;i1++)
    {
        cin>>n;
        for (i=1;i<=n;i++)
            scanf("%lld",&a[i]);
        sort(a,a+n+1);
        ans=0;
        for (i=2;i<=n;i++)
        {
            dis[i-1]=a[i]-a[i-1];
            ans=ans+(long long)dis[i-1]*(long long)(i-1)*(long long)(n-i+1);
        }
        cout<<ans<<endl;
    }
}