assertEquals(5, tw.addCategory(new CategoryPath("d","e")));
assertEquals(6, tw.getSize());
// Verify that the parents were added above in the order we expected
assertEquals(4, tw.addCategory(new CategoryPath("d")));
// Similar, but inside a category that already exists:
assertEquals(7, tw.addCategory(new CategoryPath("b", "d","e")));
assertEquals(8, tw.getSize());
// And now inside two levels of categories that already exist:
assertEquals(8, tw.addCategory(new CategoryPath("b", "d","f")));
assertEquals(9, tw.getSize());