/*
python3 ../../CompetitionHelpers/run_codeforces.py --problem A --test 0
g++ -ggdb -fsanitize=address -std=c++17 A.cpp && ./a.out <<< "1
4
0 3 5 6"
*/

#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for (int i = a; i < (b); i++)
#define trav(a, x) for (auto& a : x)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

string to_string(pii p) { return '(' + to_string(p.first) + ',' + to_string(p.second) + ')'; }
template <typename A>
string to_string(A v) { int cnt = 0; string res; for (const auto &x : v) { if (cnt++) res += " "; res += to_string(x); } return "[" + res + "]"; }
string to_string(const string& s) { return '"' + s + '"'; }
string to_string(const char* s) { return to_string((string) s); }

void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) { cerr << " " << to_string(H); debug_out(T...); }
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)

template<typename T>
void output_vector(const vector<T> &v, int start = 0, int end = -1) {
    if (end < 0) end = int(v.size());
    for (int i = start; i < end; i++)
        cout << v[i] << (i < end - 1 ? ' ' : '\n');
}

int main() {
    cin.sync_with_stdio(0); cin.tie(0);
    cin.exceptions(cin.failbit);

    int T; cin >> T; while (T--) {
        ll n; cin >> n;
        vector<ll> Arr(n); rep(i, 0, n) cin >> Arr[i];

        sort(all(Arr));

        ll ans = Arr.back();
        for (ll i = 1; i < n; i++) {
            ans -= (Arr[i] - Arr[i - 1]) * i * (n - i);
        }

        cout << ans << "\n";
    }
}