#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
using namespace std;
ifstream f("zvon.in");
ofstream g("zvon.out");
vector <int> a[100001];
bool v[100001];
int n,Q;
int dfscs(int x)
{
    v[x]=1;
    vector <int> q;
    for(int i=0;i<a[x].size();++i)if(!v[a[x][i]])
    {
        q.push_back(dfscs(a[x][i]));
    }
    int m=0;
    sort(q.begin(),q.end());
    for(int i=0,j=q.size();i<q.size();++i,--j)m=max(m,q[i]+j);
    return m;
}
int main()
{
    for(f>>Q;Q>0;--Q)
    {
        f>>n;
        for(int i=1;i<n;++i)
        {
            int x,y;
            f>>x>>y;
            a[x].push_back(y);
            a[y].push_back(x);
        }
        g<<dfscs(1)<<'\n';
        for(int i=1;i<=n;++i){v[i]=0;a[i].clear();}
    }
}