#include <bits/stdc++.h>

using namespace std;
ifstream fin("zvon.in");
ofstream fout("zvon.out");
const int NMAX = 100005;
vector < int> G[NMAX];
bitset < NMAX > B;

int dfs(int nod){
    int mx = 0;
    vector < int > A;
    B[nod] = 1;
    for(int i = 0; i < G[nod].size(); i++){
        if( B[G[nod][i]] == 0){
            A.push_back(dfs(G[nod][i]));
        }
    }
    sort(A.begin(),A.end());
    int k = A.size();
    for(int i = 0; i < A.size(); i++){
        mx = max(mx,A[i] + k);
        k--;
    }
    return mx;
}
int main()
{
    int n,t,x,y;
    fin >> t;
    for(int i = 1; i <= t; i++){
        fin >> n;
        for(int j  = 1; j <= n - 1; j++){
            fin >> x >> y;
            G[x].push_back(y);
            G[y].push_back(x);
        }
        for(int j  = 1; j <= n; j++)
            sort(G[j].begin(),G[j].end());
        fout << dfs(1) << "\n";
        for(int j  = 1; j <= n; j++){
            G[j].clear();
            B[j] = 0;
        }

    }
    return 0;
}