public void testGetUnseenCount() {
   assertEquals(0, fd.getCount("a"));
   fd.inc("b", 2);
   assertEquals(0, fd.getCount("a"));
   fd.inc("b");
   assertEquals(0, fd.getCount("a"));
 }
 public void testIncAmount() {
   fd.inc("a", 2);
   assertEquals(2, fd.getCount("a"));
   fd.inc("a", 3);
   assertEquals(5, fd.getCount("a"));
 }
 public void testInc() {
   fd.inc("a");
   assertEquals(1, fd.getCount("a"));
   fd.inc("a");
   assertEquals(2, fd.getCount("a"));
 }