#include<bits/stdc++.h>
#define Max(a,b) ((a<b)&&(a=b))
#define Min(a,b) ((a>b)&&(a=b))
#define rep(i,a,b) for(ll i=a,i##end=b;i<=i##end;++i)
#define drep(i,a,b) for(ll i=a,i##end=b;i>=i##end;--i)
#define erep(i,a) for(ll i=hd[a],y;(y=to[i]);i=nxt[i])
using namespace std;
typedef long long ll;
char C;
inline ll rd() {
    ll res=0,f=1;
    while(C=getchar(),C<48||C>57)if(C=='-')f=0;
    do res=(res<<3)+(res<<1)+(C^48);
    while(C=getchar(),C>=48&&C<=57);
    if(f)return res;
    return -res;
}
const int M=1e5+10;
ll a[M];
int main(){
    ll T=rd();
    while(T--){
        ll n=rd(),ans=0,s=0;
        rep(i,1,n)a[i]=rd();
        sort(a+1,a+n+1);
        rep(i,1,n){
            ans+=(i-1)*a[i]-s;
            s+=a[i];
        }
        printf("%lld\n",ans);
    }
}