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

typedef long long ll;
typedef long double ld;
typedef pair<int, int> p32;
typedef pair<ll, ll> p64;
typedef pair<double, double> pdd;
typedef vector<ll> v64;
typedef vector<int> v32;
typedef vector<vector<int>> vv32;
typedef vector<vector<ll>> vv64;
typedef vector<vector<p64>> vvp64;
typedef vector<p64> vp64;
typedef vector<p32> vp32;
ll MOD = 1000000007;
double eps = 1e-12;
#define forn(i, e) for (ll i = 0; i < e; i++)
#define forsn(i, s, e) for (ll i = s; i < e; i++)
#define rforn(i, s) for (ll i = s; i >= 0; i--)
#define rforsn(i, s, e) for (ll i = s; i >= e; i--)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define INF 2e18
#define fast_cin()                    \
    ios_base::sync_with_stdio(false); \
    cin.tie(NULL);                    \
    cout.tie(NULL)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((ll)(x).size())

void solve()
{
    int n;
    cin >> n;
    ll arr[n];
    for (int i = 0; i < n; i++)
        cin >> arr[i];

    sort(arr, arr + n);
    ll ans = 0, sum = 0;
    for (int i = 2; i < n; i++)
    {
        sum += arr[i - 2];
        ans -= (arr[i] * (i - 1));
        ans += sum;
    }
    cout << ans << endl;
}
int main()
{
    fast_cin();
    int t = 1;
    cin >> t;
    while (t--)
    {
        solve();
    }
    return 0;
}