fifo.enqueue("E");
assertEquals("A,B,C,D,E", fifo.dump());
fifo.enqueue("F");
assertEquals("F,B,C,D,E", fifo.dump());
fifo.enqueue("G");
assertEquals("C", fifo.dequeue());
assertEquals("D", fifo.dequeue());
assertEquals("E", fifo.dequeue());
assertEquals("F", fifo.dequeue());
assertEquals("G", fifo.dequeue());
assertNull(fifo.dequeue());