#include<bits/stdc++.h>
using namespace std;
#define reg register
typedef long long ll;
#define rep(i,a,b) for(reg int i=a,i##end=b;i<=i##end;++i)
#define drep(i,a,b) for(reg int i=a,i##end=b;i>=i##end;--i)
typedef pair <int,int> Pii;
typedef unsigned long long ull;
typedef double db;
#define mp make_pair
#define pb push_back
#define Mod1(x) ((x>=P)&&(x-=P))
#define Mod2(x) ((x<0)&&(x+=P))
template <class T> inline void cmin(T &a,T b){ ((a>b)&&(a=b)); }
template <class T> inline void cmax(T &a,T b){ ((a<b)&&(a=b)); }

char IO;
template <class T=int> T rd(){
    T s=0; int f=0;
    while(!isdigit(IO=getchar())) if(IO=='-') f=1;
    do s=(s<<1)+(s<<3)+(IO^'0');
    while(isdigit(IO=getchar()));
    return f?-s:s;
}
const int N=1e5+10;


int a[N];

int main(){
    rep(kase,1,rd()) {
        int n=rd();
        rep(i,1,n) a[i]=rd();
        sort(a+1,a+n+1);
        ull s=0,ans=0;
        rep(i,1,n) {
            ull x=a[i];
            ans+=x*(i-1)-s;
            s+=x;
        }
        cout<<ans<<endl;
    }
}