#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < n; ++i) {
      for (int j = 0; j < m; ++j) {
        if (i == 0 && j == 0) {
          cout << 'W';
        } else {
          cout << 'B';
        }
      }
      cout << "\n";
    }
  }
  return 0;
}
