n = int(input()) for case_idx in range(n): a, b = map(int, input().split()) pattern = [] for i in range(a): left = min(i, a - 1 - i) right = max(i, a - 1 - i) row = [' '] * a row[left] = 'X' if left != right: row[right] = 'X' pattern.append(''.join(row)) for _ in range(b): for row in pattern: print(row) if case_idx < n - 1: print()