#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define Rep(i,a,b) for(register int i=(a);i<=(b);++i)
#define rep(i,a,b) for(register int i=(a);i<(b);++i)
#define Dep(i,a,b) for(register int i=(a);i>=(b);--i)
#define mem(x,v) memset(x,v,sizeof(x))
#define gc getchar
#define pc putchar
inline ll read(){
    ll x = 0,f = 0;char c = gc();
    for(;!isdigit(c);c=gc()) f|=(c=='-');
    for(;isdigit(c);c=gc()) x = x * 10 + (c - '0');
    return f ? -x : x;
}
inline void write(ll x){if(x < 0) pc('-'),x=-x;if(x>=10) write(x / 10);pc(x%10+'0');}
inline void writeln(ll x){write(x),pc('\n');}
inline void wri(ll x){write(x),pc(' ');}
const int maxn = 1e6+233;
int a[maxn],n;
void solve(){
    n = read();
    Rep(i,1,n) a[i] = read();
    sort(a+1,a+1+n);
    ll ans = 0;
    Rep(i,1,n){
        ans += 1ll*a[i] * (i-1);
        ans -= 1ll*a[i] * (n-i);
    }writeln(ans);
}
int main(){
    int T = read();
    while(T--) solve();
    return 0;
}