### Question:
UnregisterCommand extends PlayerCommand { @Override public MessageKey getArgumentsMismatchMessage() { return MessageKey.USAGE_UNREGISTER; }  @Override void runCommand(Player player, List<String> arguments); @Override MessageKey getArgumentsMismatchMessage();  }### Answer:
@Test public void shouldDefineArgumentMismatchMessage() { assertThat(command.getArgumentsMismatchMessage(), equalTo(MessageKey.USAGE_UNREGISTER)); }