#include<bits/stdc++.h>
#define ls ch[x][0]
#define rs ch[x][1]
#define ll long long
using namespace std;

inline ll read(){
    ll num=0,neg=1;char c=getchar();
    while(!isdigit(c)){if(c=='-')neg=-1;c=getchar();}
    while(isdigit(c)){num=(num<<3)+(num<<1)+c-'0';c=getchar();}
    return num*neg;
}

ll T,n,a[100010],ans,sum,cnt;



int main(){
    T=read();
    while(T--)
    {
        n=read(),ans=0,sum=0,cnt=0;
        for(int i=1;i<=n;i++) a[i]=read();
        sort(a+1,a+n+1);
        for(int i=1;i<=n;i++)
        {
            ans+=a[i]*cnt-sum;
            sum+=a[i],cnt++;
        }cout<<ans<<endl;
    }return 0;
}