#include <cstdio>
#include <algorithm>
#define RI register int
#define int long long

int const MAXN = 1e5 + 5;
int a[MAXN];

signed main() {
    int T; scanf("%lld", &T);
    while (T--) {
        int n; scanf("%lld", &n);
        for (RI i = 1; i <= n; ++i)
            scanf("%lld", &a[i]);
        std :: sort(a + 1, a + 1 + n);
        int ans = 0;
        for (RI i = 1; i <= n; ++i) { 
            ans += a[i] * (i - 1); 
            ans -= a[i] * (n - i);
        } 
        printf("%lld\n", ans);
    }
    return 0;
}