#include <bits/stdc++.h>
using namespace std;
const int inf = 2000000000;
const long long infLL = 9000000000000000000;
template <typename first, typename second>
ostream& operator<<(ostream& os, const pair<first, second>& p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
template <typename T>
ostream& operator<<(ostream& os, const vector<T>& v) {
  os << "{";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin()) os << ", ";
    os << *it;
  }
  return os << "}";
}
template <typename T>
ostream& operator<<(ostream& os, const set<T>& v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin()) os << ",";
    os << *it;
  }
  return os << "]";
}
template <typename T>
ostream& operator<<(ostream& os, const multiset<T>& v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin()) os << ", ";
    os << *it;
  }
  return os << "]";
}
template <typename first, typename second>
ostream& operator<<(ostream& os, const map<first, second>& v) {
  os << "[";
  for (auto it = v.begin(); it != v.end(); ++it) {
    if (it != v.begin()) os << ", ";
    os << it->first << " = " << it->second;
  }
  return os << "]";
}
void faltu() { cerr << '\n'; }
template <typename T>
void faltu(T a[], int n) {
  for (int i = 0; i < n; ++i) cerr << a[i] << ' ';
  cerr << '\n';
}
template <typename T, typename... hello>
void faltu(T arg, const hello&... rest) {
  cerr << arg << ' ';
  faltu(rest...);
}
const int mx = 3e5 + 5;
vector<int> adjlist[mx];
int dp[mx];
int n;
int ans;
void dfs(int u, int par) {
  vector<int> store;
  for (auto v : adjlist[u]) {
    if (v == par) continue;
    dfs(v, u);
    store.push_back(dp[v]);
  }
  sort(store.begin(), store.end(), greater<int>());
  int temp = 0;
  for (int i = 0; i < (int)store.size() && i < 2; ++i) {
    temp += 1 + store[i];
  }
  if (par)
    temp += 2;
  else
    ++temp;
  temp += (int)adjlist[u].size();
  if (par) {
    --temp;
    if ((int)adjlist[u].size() == 2)
      --temp;
    else if ((int)adjlist[u].size() == 3)
      temp -= 2;
    else if ((int)adjlist[u].size() > 3)
      temp -= 2;
  } else {
    if ((int)adjlist[u].size() == 1)
      --temp;
    else if ((int)adjlist[u].size() == 2)
      temp -= 2;
    else if ((int)adjlist[u].size() > 2)
      temp -= 2;
  }
  ans = max(ans, temp);
  if (!store.empty()) dp[u] = store[0] + 1;
  if (par) {
    dp[u] += (int)adjlist[u].size();
    --dp[u];
    if ((int)adjlist[u].size() == 2)
      --dp[u];
    else if ((int)adjlist[u].size() > 2)
      --dp[u];
  } else {
    dp[u] += (int)adjlist[u].size();
    if ((int)adjlist[u].size() == 1)
      --dp[u];
    else if ((int)adjlist[u].size() > 1)
      --dp[u];
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int q;
  cin >> q;
  while (q--) {
    cin >> n;
    for (int i = 1; i <= n; ++i) {
      dp[i] = 0;
      adjlist[i].clear();
    }
    for (int i = 0; i < n - 1; ++i) {
      int u, v;
      cin >> u >> v;
      adjlist[u].push_back(v);
      adjlist[v].push_back(u);
    }
    ans = 0;
    dfs(1, 0);
    cout << ans << '\n';
  }
}
