### Question:
BlockUnblockFilter extends
		StateBasedBlockerFilter<BlockedUnblockedState> { public void unblock() { state(BlockedUnblockedState.UNBLOCK); } BlockUnblockFilter(BlockedUnblockedState initial); void block(); void unblock();  }### Answer:
@Test public void can_unblock_unblocked() throws Exception { assertEquals(BlockedUnblockedState.UNBLOCK, m_buf.state()); m_buf.unblock(); assertEquals(BlockedUnblockedState.UNBLOCK, m_buf.state()); }