#include<bits/stdc++.h>
#define mp make_pair
#define fi first
#define se second
#define debug(x) cerr<<#x<<" = "<<(x)<<endl
#define eps 1e-9
#define pi acos(-1.0)
using namespace std;
void test(){cerr<<"\n";}
template<typename T,typename... Args>void test(T x,Args... args){cerr<<x<<" ";test(args...);}
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const int MAXN=(int)1e5+10;
const int MOD=(int)1e9+7;
void Main(){
    int n;
    cin>>n;
    vector<int>a(n);
    for(int i=0;i<n;i++)cin>>a[i];
    sort(a.begin(),a.end());
    ll cnt=0;
    ll sum=0;
    ll ans=0;
    for(auto x:a){
        ans+=x*cnt-sum;
        sum+=x;
        cnt++;
    }
    cout<<ans<<"\n";
}
int main()
{
    #ifdef BanFcc
        freopen("in.txt","r",stdin);
    #else
        ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    #endif
    int T=1;
    cin>>T;
    for(int ca=1;ca<=T;ca++){
        Main();
    }
    return 0;
}