import java.io.*;
import java.math.BigDecimal;
import java.util.*;

public class Main {
    public static void main(String[] args) throws IOException {
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
        FastScanner in=new FastScanner();
        int T = in.nextInt();
        while (T-->0){
            int n=in.nextInt();
            long a[]=new long[n];
            for(int i=0;i<n;i++) a[i]=in.nextInt();
            Arrays.sort(a);
            long res=0;
            long sum=0;
            for(int i=1;i<n;i++){
                sum+=i*(a[i]-a[i-1]);
                res+=sum;
            }
            out.println(res);
        }
        out.flush();
    }static class FastScanner {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st=new StringTokenizer("");
        String next() {
            while (!st.hasMoreTokens())
                try {
                    st=new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }
        int[] readArray(int n) {
            int[] a=new int[n];
            for (int i=0; i<n; i++) a[i]=nextInt();
            return a;
        }
        long nextLong() {
            return Long.parseLong(next());
        }
    }
}