TestWeakListeners.java

/*
  GRANITE DATA SERVICES
  Copyright (C) 2012 GRANITE DATA SERVICES S.A.S.

  This file is part of Granite Data Services.

  Granite Data Services is free software; you can redistribute it and/or modify
  it under the terms of the GNU Library General Public License as published by
  the Free Software Foundation; either version 2 of the License, or (at your
  option) any later version.

  Granite Data Services is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License
  for more details.

  You should have received a copy of the GNU Library General Public License
  along with this library; if not, see <http://www.gnu.org/licenses/>.
*/

package org.granite.client.test.tide.javafx;

import java.util.List;

import javafx.collections.ListChangeListener;
import javafx.collections.ListChangeListener.Change;
import javafx.collections.WeakListChangeListener;

import org.granite.client.util.javafx.ListListenerHelper;
import org.junit.Assert;
import org.junit.Test;


public class TestWeakListeners {
    
    @Test
    public void testWeakListeners() throws Exception {
    	ListListenerHelper<Person> helper = new ListListenerHelper<Person>();
    	
    	@SuppressWarnings("unchecked")
		ListChangeListener<Person>[] references = new ListChangeListener[2];
    	references[0] = new TestListChangeListener();
    	references[1] = new TestListChangeListener();
    	
    	WeakListChangeListener<Person> weakListener1 = new WeakListChangeListener<Person>(references[0]);
    	WeakListChangeListener<Person> weakListener2 = new WeakListChangeListener<Person>(references[1]);
    	
    	helper.addListener(weakListener1);
    	helper.addListener(weakListener2);
    	
    	Assert.assertEquals("Listeners before gc", 2, helper.getListChangeListenersListenersSize());
    	
    	references[0] = null;
    	references[1] = null;
    	
    	System.gc();
    	
    	final Boolean[] changed = new Boolean[1];
    	
    	helper.addListener(new ListChangeListener<Person>() {
			@Override
			public void onChanged(ListChangeListener.Change<? extends Person> change) {
				changed[0] = true;
			}    		
    	});
    	
    	helper.fireValueChangedEvent(new MockChange());
    	
    	Assert.assertEquals("Listeners after gc", 1, helper.getListChangeListenersListenersSize());
    	Assert.assertTrue("Last one triggered", changed[0]);
    }
    
    @Test
    public void testWeakListeners2() throws Exception {
    	ListListenerHelper<Person> helper = new ListListenerHelper<Person>();
    	
    	@SuppressWarnings("unchecked")
		ListChangeListener<Person>[] references = new ListChangeListener[3];
    	references[0] = new TestListChangeListener();
    	references[1] = new TestListChangeListener();
    	references[2] = new TestListChangeListener();
    	
    	WeakListChangeListener<Person> weakListener1 = new WeakListChangeListener<Person>(references[0]);
    	WeakListChangeListener<Person> weakListener2 = new WeakListChangeListener<Person>(references[1]);
    	WeakListChangeListener<Person> weakListener3 = new WeakListChangeListener<Person>(references[2]);
    	
    	final Boolean[] changed = new Boolean[1];
    	
    	helper.addListener(weakListener1);
    	helper.addListener(weakListener2);    	
    	helper.addListener(new ListChangeListener<Person>() {
			@Override
			public void onChanged(ListChangeListener.Change<? extends Person> change) {
				changed[0] = true;
			}    		
    	});
    	helper.addListener(weakListener3);
    	
    	Assert.assertEquals("Listeners before gc", 4, helper.getListChangeListenersListenersSize());
    	
    	references[1] = null;
    	
    	System.gc();
    	
    	helper.removeListener(weakListener1);
    	
    	helper.fireValueChangedEvent(new MockChange());
    	
    	Assert.assertEquals("Listeners after gc", 2, helper.getListChangeListenersListenersSize());
    	Assert.assertTrue("Last one triggered", changed[0]);
    }
    
    @Test
    public void testWeakListeners3() throws Exception {
    	ListListenerHelper<Person> helper = new ListListenerHelper<Person>();
    	
    	@SuppressWarnings("unchecked")
		ListChangeListener<Person>[] references = new ListChangeListener[3];
    	references[0] = new TestListChangeListener();
    	references[1] = new TestListChangeListener();
    	references[2] = new TestListChangeListener();
    	
    	WeakListChangeListener<Person> weakListener1 = new WeakListChangeListener<Person>(references[0]);
    	WeakListChangeListener<Person> weakListener2 = new WeakListChangeListener<Person>(references[1]);
    	WeakListChangeListener<Person> weakListener3 = new WeakListChangeListener<Person>(references[2]);
    	
    	final Boolean[] changed = new Boolean[1];
    	
    	helper.addListener(weakListener1);
    	helper.addListener(new ListChangeListener<Person>() {
			@Override
			public void onChanged(ListChangeListener.Change<? extends Person> change) {
				changed[0] = true;
			}    		
    	});
    	helper.addListener(weakListener2);    	
    	helper.addListener(weakListener3);
    	
    	Assert.assertEquals("Listeners before gc", 4, helper.getListChangeListenersListenersSize());
    	
    	references[1] = null;
    	
    	System.gc();
    	
    	helper.removeListener(weakListener1);
    	
    	helper.fireValueChangedEvent(new MockChange());
    	
    	Assert.assertEquals("Listeners after gc", 2, helper.getListChangeListenersListenersSize());
    	Assert.assertTrue("Last one triggered", changed[0]);
    }
    
    public static class TestListChangeListener implements ListChangeListener<Person> {
		@Override
		public void onChanged(ListChangeListener.Change<? extends Person> change) {
		}    	
    }
    
    public static class MockChange extends Change<Person> {
    	public MockChange() {
    		super(null);
    	}
    	
		@Override
		public int getFrom() {
			return 0;
		}
	
		@Override
		protected int[] getPermutation() {
			return null;
		}
	
		@Override
		public List<Person> getRemoved() {
			return null;
		}
	
		@Override
		public int getTo() {
			return 0;
		}
	
		@Override
		public boolean next() {
			return false;
		}
	
		@Override
		public void reset() {
		}
    }
}