@Test
	public void testZeroTree() {
	
	Field field; 
		
		try {
			field = collector.getClass().getDeclaredField("observedTrees");
			field.setAccessible(true);
			ArrayList<Tree> treeList = (ArrayList<Tree>) field.get(collector);	
			assertEquals(treeList.size(), 0);
		} catch (NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException e) {} 	
	}