#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<int, ll> pil;
typedef pair<ll, int> pli;
typedef pair<ll, ll>pll;

const ll MOD = 1e9 + 7;
const int MAXN = 1e5;

ll gcd(ll a, ll b)
{
    return b == 0 ? a : gcd(b, a % b);
}
ll lcm(ll a, ll b)
{
    return a / gcd(a, b) * b;
}
ll pow(ll a, ll b)
{
    ll res = 1;
    while (b)
    {
        if (b & 1) res = res * a % MOD;
        a = a * a % MOD;
        b >>= 1;
    }
    return res;
}

struct unionset
{
    int size;
    vector<int> fa;
    unionset(int _size = 0)
    {
        size = _size;
        fa.clear();
        for (int i = 0; i < size; i++)fa.push_back(i);
    }
    int getfa(int x)
    {
        return fa[x] == x ? x : fa[x] = getfa(fa[x]);
    }
    bool merge(int a, int b)
    {
        int faa = getfa(a);
        int fbb = getfa(b);
        if (faa > fbb)swap(faa, fbb);
        if (faa != fbb)
        {
            fa[fbb] = faa;
        }
    }
};
struct graph
{
    struct edge
    {
        int v, nxt;
        int d;
        edge(int vv = 0, int dd = 0, int nn = 0)
        {
            v = vv;
            d = dd;
            nxt = nn;
        }
    };
    static const int MAXN = 1e5;
    static const int MAXM = 1e6;
    vector<int>h;
    vector<edge>e;

    graph()
    {
        h.clear();
        e.clear();
        for (int i = 0; i < MAXN; i++)
        {
            h.push_back(-1);
        }
    }
    void addedge(int u, int v, int d = 0)
    {
        e.push_back(edge());
        e[e.size() - 1].v = v;
        e[e.size() - 1].d = d;
        e[e.size() - 1].nxt = h[u];
        h[u] = e.size() - 1;
    }
};

int judge(ll a, ll b, ll c)
{
    int ans = 0;
    while (a >= b)
    {
        a = a - b + ll(b * (1.0 - 1.0 * c / 100));
        ans++;
    }
    return ans;
}


int main()
{
    int T;
    cin >> T;
    while (T--)
    {
        int n;
        scanf("%d", &n);
        vector<ll>a;
        for (int i = 0; i < n; i++)
        {
            ll x;
            scanf("%lld", &x);
            a.push_back(x);
        }
        sort(a.begin(), a.end());
        ll pre = a[0];
        ll ans = 0;
        for (int i = 1; i < n; i++)
        {
            ans += a[i] * i  - pre;
            pre += a[i];
        }
        printf("%lld\n", ans);
    }
}