def main():
    lines: list[str] = []
    t = int(input())
    while (t != 0):
        lines.append(input())
        t -= 1

    for line in lines:
        h, w = [int(n) for n in line.split()]
        for y in range(h):
            print('*' * ((w * 3) + 1))
            row = '*..' * w + '*'

            print(row)
            print(row)

        print('*' * ((w * 3) + 1))
        print()

if __name__ == "__main__":
    main()