#include <bits/stdc++.h>
// {{{ Definitions
#define reg register
#define pr std::pair<int, int>
#define fi first
#define se second
#define FIN(s) freopen(s, "r", stdin)
#define FOUT(s) freopen(s, "w", stdout)
#define FERR(s) freopen(s, "w", stderr)
#define debug(...) fprintf(stderr, __VA_ARGS__)
#define dputs(s) fprintf(stderr, s"\n")
#define rep(i, l, r) for (int i = l; i <= r; ++i)
#define lep(i, l, r) for (int i = l; i < r; ++i)
#define irep(i, r, l) for (int i = r; i >= l; --i)
#define ilep(i, r, l) for (int i = r; i > l; --i)
#define Rep(i, n) rep(i, 1, n)
#define Lep(i, n) lep(i, 1, n)
#define IRep(i, n) irep(i, n, 1)
#define ILep(i, n) ilep(i, n, 1)
typedef unsigned long long ll;
typedef long double ld;
// }}}
// {{{ Modular
namespace modular {
    const int MOD = 1000000007;
    inline int add(int x, int y) { return (x += y) >= MOD ? x -= MOD : x; }
    inline void inc(int &x, int y) { (x += y) >= MOD ? x -= MOD : 0; }
    inline int mul(int x, int y) { return 1LL * x * y % MOD; }
    inline int qpow(int x, int y) {
        int ans = 1;
        for (; y; y >>= 1, x = mul(x, x))
            if (y & 1)
                ans = mul(ans, x);
        return ans;
    }
}; // namespace modular
// }}}
// {{{ Base
namespace Base {
    template <typename Tp> inline Tp input() {
        Tp x = 0, y = 1;
        char c = getchar();
        while ((c < '0' || '9' < c) && c != EOF) {
            if (c == '-')
                y = -1;
            c = getchar();
        }
        if (c == EOF)
            return 0;
        while ('0' <= c && c <= '9')
            x = x * 10 + c - '0', c = getchar();
        return x *= y;
    }
    template <typename Tp> inline void read(Tp &x) { x = input<Tp>(); }
    template <typename Tp> inline void chmax(Tp &x, Tp y) { x < y ? x = y : 0; }
    template <typename Tp> inline void chmin(Tp &x, Tp y) { x > y ? x = y : 0; }
}; // namespace Base
// }}}
using namespace Base;

#define MAX_N 200007

int N;
ll a[MAX_N];

void solve() {
    read(N);
    Rep(i, N) read(a[i]);
    std::sort(a + 1, a + N + 1);
    ll ans = 0, sum = 0;
    Rep(i, N) {
        ans += (ll)1 * (i - 1) * a[i] - sum;
        sum += a[i];
    }
    printf("%lld\n", ans);
}

int main() {
#ifndef ONLINE_JUDGE
    FIN("a.in");
    // FOUT("a.out");
    // FERR("a.log");
#endif
    int T = input<int>();
    while (T--) solve();
    return 0;
}