CodeChef::HORSES

 

#include <bits/stdc++.h>
using namespace std ;

int main (){
    int t ;
    cin >> t ;
    while (t--){
        int n ;
        cin >> n ;
        int s[n];
        for (int i = 0; i < n; ++i) {
            cin >> s[i];
        }
        sort(s,s+n);
        long long int smallest{INT64_MAX};
        for (int i = 0; i < n - 1; ++i) {
            if (s[i+1] - s[i] < smallest){
                smallest = s[i+1] - s[i];
            }
        }
        cout << smallest << '\n';

    }
    return 0;
}