include<bits stdc++.h="">

using namespace std; int main() { int i,n,t; unsigned long int x,dif; vector<unsigned long="" int="">ch; cin>>t; while(t--) { cin>>n; for(i=0;i<n;i++) {="" cin="">>x; ch.push_back(x); } sort(ch.begin(),ch.end()); dif=ch[1]-ch[0]; for(i=1;i<n-1;i++) { if(ch[i+1]-ch[i]<dif) dif=ch[i+1]-ch[i]; } cout<<dif<<endl; } return 0; }