#include <bits/stdc++.h>
using namespace std;
int a[100005];
int main() {
  int T;
  scanf("%d", &T);
  for (int t = 1; t <= T; t++) {
    int N;
    scanf("%d", &N);
    int b[100005];
    for (int i = 1; i <= N; i++) {
      scanf("%d", &b[i]);
    }
    sort(b + 1, b + N + 1);
    int mid = N % 2 ? N / 2 + 1 : N / 2;
    int lo = mid, hi = mid;
    if (N % 2 == 0)
      hi++;
    else {
      printf("%d ", b[mid]);
      lo--;
      hi++;
    }
    if (N % 2 == 0) {
      while (lo > 0 && hi <= N) {
        printf("%d %d ", b[lo], b[hi]);
        lo--;
        hi++;
      }
    } else {
      if (b[mid] - b[lo] > b[hi] - b[mid]) {
        while (lo > 0 && hi <= N) {
          printf("%d %d ", b[hi], b[lo]);
          lo--;
          hi++;
        }
      } else {
        while (lo > 0 && hi <= N) {
          printf("%d %d ", b[lo], b[hi]);
          lo--;
          hi++;
        }
      }
    }
    printf("\n");
  }
  return 0;
}
