/*
 * Author: Kewth

 * Date:
  echo -n '  ' && date +%Y.%m.%d # Type "!!sh" in Vim.

 * Solution:
  To be updated after "Accept".

 * Digression:

 * CopyRight:
          %%%%%%%%%%%
        %%%%    %%%%
       %%   %%━━■%%
      %%   %%     %%
     %%%   %%   %  %%
    %% %   %%%%■%  %%
  %%%   %%       %%%
  %%%%%%%%%%%%%%■%%
        %%%%%%
 */

#include <cstdio>
#include <algorithm>
#define debug(...) fprintf(stderr, __VA_ARGS__)

typedef long long ll;

static struct {
    inline operator int () { int x; return scanf("%d", &x), x; }
    inline operator ll () { ll x; return scanf("%lld", &x), x; }
    template<class T> inline void operator () (T &x) { x = *this; }
    template<class T, class ...A> inline void operator () (T &x, A &...a)
    { x = *this; this -> operator () (a...); }
} read;

const int maxn = 100005;
ll a[maxn];

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