#include<bits/stdc++.h>
using namespace std;
inline int read()
{
    int x=0;char ch;
    while(!isdigit(ch=getchar()));x=ch-48;
    while(isdigit(ch=getchar()))x=x*10+ch-48;
    return x;
}
const int MAXN=1e5+5;
int T,n,a[MAXN];
long long ans,w[MAXN];
int main()
{
    T=read();
    while(T--)
    {
        n=read();
        for(int i=1;i<=n;i++)a[i]=read();
        sort(a+1,a+n+1);
        for(int i=n;i>=1;i--)w[i]=w[i+1]+a[i];
        for(int i=1;i<n;i++)
            ans+=w[i+1]-(long long)(n-i)*a[i];
        printf("%lld\n",ans);
        ans=0;
        for(int i=1;i<=n;i++)w[i]=0;
    }
    return 0;
}