#include<bits/stdc++.h>
using namespace std;
int n,a[100100];
long long sum[100100],ans=0;
inline void solve()
{
    cin>>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++)
    {
        sum[i]=sum[i-1]+a[i];
        ans+=1ll*a[i]*i-sum[i];
    }
    cout<<ans<<endl;
}
int main()
{
    int T;cin>>T;
    while(T--) solve();
}