def it_fails_on_blank_string(self):
     assert not is_board_string("")
     assert not is_board_string("    ")
     assert not is_board_string("   \r\n ")
 def it_fails_on_illegal_characters(self):
     assert not is_board_string(self.input + "z")
 def it_fails_on_numeric_string(self):
     assert not is_board_string("42")
 def it_recognizes_board_string(self):
     assert is_board_string(self.input)