/* package codechef; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Codechef
{
    public static void main (String[] args) throws java.lang.Exception
    {
        // your code goes here
        Scanner sc = new Scanner(System.in);
        int t = sc.nextInt();
        while(t-- != 0){

            int N = sc.nextInt();
            int k = sc.nextInt();
            int[] a = new int[N];
            for(int i=0; i<N; i++){

                a[i] = sc.nextInt();
              //  System.out.print(a[i] + " ");
            }

            int c = cnt(a,N,k);
            System.out.println(c);
        }
    }
    static int cnt(int[] a, int n, int k){

        int i=0;
        int c = 0;
        while(i < n){

            int sum = a[i];
           // System.out.println("i inside while loop is " + i);
            if(sum > k) {
                return -1;
            }
            else{
                if(sum <= k){
                    c+=1;
                }
            }
            int f = i;
            for(int j = f+1; j<n; j++){
               // System.out.println(a[j] + " ");
                sum += a[j];
               // System.out.println("i is " + i);
                if(sum <= k){
                    i = j+1;
                }
                else{
                   if(j == n-1){
                            i = n;
                            if(a[j] <= k)  c+=1;
                            break;
                   }
                   else{
                        i = j;
                        break;
                    }
                }
               //  i = j;
            }

        }
        return(c);
    }
}