#include<bits/stdc++.h>
#define debug(x) cerr<<#x<<" = "<<x
#define sp <<"  "
#define el <<endl
#define fgx cerr<<"-----------------------------------"<<endl
#define LL long long
#define DB double
#define pb push_back
using namespace std;
inline LL read(){
    LL nm=0; bool fh=1; char cw=getchar();
    for(;!isdigit(cw);cw=getchar()) fh^=(cw=='-');
    for(;isdigit(cw);cw=getchar()) nm=nm*10+(cw-'0');
    return fh?nm:-nm;
}
#define mod 1000000007
namespace  CALC{
    inline int add(int x,int y){return (x+y>=mod)?(x+y-mod):(x+y);}
    inline int mns(int x,int y){return (x-y<0)?(x-y+mod):(x-y);}
    inline int mul(LL x,LL y){return x*y%mod;}
    inline void upd(int &x,int y){x=(x+y>=mod)?(x+y-mod):(x+y);}
    inline void dec(int &x,int y){x=(x-y<0)?(x-y+mod):(x-y);}
    inline int qpow(int x,LL sq){LL res=1;for(;sq;sq>>=1,x=mul(x,x))if(sq&1)res=mul(res,x);return res;}
}using namespace CALC;
#define M 500200
#define INF 2000000000000000000ll
#define ULL unsigned long long
int n,m;
ULL ans,a[M];
int main(){
    for(int Cas=read();Cas;--Cas){
        n=read();
        for(int i=1;i<=n;i++) a[i]=read();
        ans=0,sort(a+1,a+n+1);
        for(int i=1;i<n;i++)
            ans+=(ULL)i*(ULL)(n-i)*(a[i+1]-a[i]);
        printf("%llu\n",ans);
    }
    return 0;
}