INCLUDE<IOSTREAM>
INCLUDE<CMATH>
using namespace std;
void f()
{
int n,a[53],min,t;
cin>>n;
for(int i=0;i<n;++i) cin>>a[i];
min=abs(a[0]-a[1]);
for(int i=0;i<n;++i){
for(int j=i+1;j<n;++j){
t=abs(a[i]-a[j]);
if(t<min) min=t;
}
}
cout<<min<<endl;
}
int main(){
int t;
cin>>t;
for(int i=0;i<t;++i) f();
return 0;
}
