#include<fstream>
#include<vector>
#define NMAX 100010

using namespace std;

ifstream f("zvon.in");
ofstream g("zvon.out");

vector<int> v[NMAX];
int i, n, T, x, y, vz[NMAX], nr[NMAX];

void DFS(int nod)
{
    int i;

    vz[nod]=1;

    for (i=1; i<v[nod].size(); ++i)
        if (!vz[v[nod][i]])
        {
            DFS(v[nod][i]);
            nr[nod]=max(nr[nod], nr[v[nod][i]]);
        }

    nr[nod]++;
}

int main()
{
    f>>T;

    while (T--)
    {
        f>>n;

        for (i=1; i<n; ++i)
        {
            f>>x>>y;
            v[x].push_back(y);
            v[y].push_back(x);
        }

        DFS(1);

        if (n==1) g<<"0\n";
        else g<<nr[1]<<"\n";

        for (i=1; i<=n; ++i)
        {
            v[i].clear();
            vz[i]=nr[i]=0;
        }
    }

    f.close();
    g.close();
    return 0;
}