#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>

//#include <cstdio>
//#include <iostream>
//#include <algorithm>
//#include <cmath>
//#include <string>
//#include <vector>
//#include <set>
//#include <queue>
//#include <cstring>
//#include <cassert>

#define X first
#define Y second
#define PB push_back
#define MP make_pair
#define EB emplace_back
#define mset(var,val) memset(var,val,sizeof(var))
#define IOS ios::sync_with_stdio(false);cin.tie(0),cout.tie(0)
#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
//using namespace __gnu_pbds;
//using namespace __gnu_cxx;
using namespace std;

namespace ___ {

#ifdef local
#define dbg(args...) do { cout << #args << " -> "; err(args); } while (0)
void err() {
    cout  << endl;
}
template<template<typename...> class T, typename t, typename... Args>
void err(T<t> a, Args... args) {
    for (auto x: a)
        cout << x << ' ';
    err(args...);
}
template<typename T, typename... Args>
void err(T a, Args... args) {
    cout << a << ' ';
    err(args...);
}
#else
#define dbg(...)
#endif

//#ifdef local
//typedef long long LL;
//#else
//typedef __int128 LL;
//#endif // local

int _ = 0;
void testcase() {
    cout << "Case " << (++_) << ": ";
}
}
template<class T>
inline bool scan(T&ret) {
    char c;
    int sgn;
    if(c=getchar(),c==EOF)
        return 0;
    while(c!='-' and (c<'0' or c>'9'))
        c=getchar();
    sgn=(c=='-')?-1:1;
    ret=(c=='-')?0:(c-'0');
    while(c=getchar(),c>='0' and c<='9')
        ret=ret*10+(c-'0');
    ret*=sgn;
    return 1;
}
template<class T>
inline void out(T x) {
    if(x>9)
        out(x/10);
    putchar(x%10+'0');
}
using namespace ___;
typedef long long ll;
typedef unsigned long long ull;
typedef unsigned int uint;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const int inf = 0x3f3f3f3f;
const ll  INF = 0x3f3f3f3f3f3f3f3fLL;
const double PI = acos(-1.0);
const double eps = 1e-6;
const int mod = 998244353;
const int lim = 1e3;
const int N = 2e6+10;
const int M = 1e6+10;

#define lson (rt<<1)
#define rson (rt<<1|1)


ll qpow(ll a, ll b) {
    ll ans = 1;
    for(;b;b>>=1){
        if(b&1) ans = ans*a%mod;
        a=a*a%mod;
    }
    return ans;
}

ll a[N];


void work(){
    int n;
    cin >> n;
    rep(i,n){
        cin >> a[i];
    }
    if (n == 1) {
        cout << 0 << "\n";
        return;
    }
    sort(a, a+n);
    ll pre = a[0];
    int cnt = 1;
    ll ans = 0;
    for (int i = 1; i < n; ++i) {
        ans += a[i]*cnt - pre;
        pre += a[i];
        cnt++;
    }
    cout << ans << "\n";


}

int main() {
#ifdef local
    freopen("in.txt","r",stdin);
//    freopen("out.txt","w",stdout);
#endif // local
    IOS;
//    init();
    int t;
    cin>>t;
//
    for(; t--;)
    work();
//    return 0;
}