#include <bits/stdc++.h>
using namespace std;
class Solution {
 public:
  static bool check(const vector<int> &a) {
    for (int i = 1; i + 1 < a.size(); ++i) {
      if (std::abs(a[i] - a[i - 1]) > std::abs(a[i + 1] - a[i])) {
        return false;
      }
    }
    return true;
  }
  void arrange(vector<int> &a) const {
    sort(a.begin(), a.end());
    vector<int> ret;
    ret.reserve(a.size());
    int left = 0, right = a.size() - 1;
    while (left <= right) {
      ret.push_back(a[left++]);
      if (left <= right) {
        ret.push_back(a[right--]);
      }
    }
    reverse(ret.begin(), ret.end());
    a = ret;
  }
  void solve(int n) {
    vector<int> a(n);
    for (int i = 0; i < n; ++i) {
      scanf("%d", &a[i]);
    }
    arrange(a);
    for (int i = 0; i < n; ++i) {
      printf("%d ", a[i]);
    }
    cout << endl;
  }
  void gen() {
    for (int iter = 0; iter < 40; ++iter) {
      int n = rand() % 30;
      vector<int> a(n);
      for (int i = 0; i < n; ++i) {
        a[i] = rand() % 50;
      }
      arrange(a);
      cout << endl;
      if (!check(a)) {
        for (int i = 0; i < n; ++i) {
          cout << a[i] << " ";
        }
        exit(1);
      }
    }
  }
};
int main(int, char **) {
  int tests;
  cin >> tests;
  while (tests--) {
    int n;
    cin >> n;
    Solution solution;
    solution.solve(n);
  }
  return 0;
}
