/*******************************************************************************
 * Copyright (c) 2000, 2016 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.tests.junit;

import static org.junit.Assert.assertArrayEquals;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.TreeColumn;
import org.eclipse.swt.widgets.TreeItem;
import org.junit.Before;
import org.junit.Test;

/**
 * Automated Test Suite for class org.eclipse.swt.widgets.Tree
 *
 * @see org.eclipse.swt.widgets.Tree
 */
public class Test_org_eclipse_swt_widgets_Tree extends Test_org_eclipse_swt_widgets_Composite {

@Override
@Before
public void setUp() {
	super.setUp();
	tree = new Tree(shell, SWT.MULTI);
	setWidget(tree);
}

@Override
@Test
public void test_ConstructorLorg_eclipse_swt_widgets_CompositeI() {
	try {
		tree = new Tree(null, 0);
		fail("No exception thrown for parent == null");
	}
	catch (IllegalArgumentException e) {
	}

	int[] cases = {0, SWT.BORDER};
	for (int i = 0; i < cases.length; i++)
		tree = new Tree(shell, cases[i]);

	cases = new int[]{0, 10, 100};
	for (int j = 0; j < cases.length; j++) {
		for (int i = 0; i < cases[j]; i++) {
			new TreeItem(tree, 0);
		}
		assertEquals(cases[j], tree.getItemCount());
		tree.removeAll();
	}
}

@Override
@Test
public void test_computeSizeIIZ() {
}

@Test
public void test_deselectAll() {
	int number = 15;
	TreeItem[] items = new TreeItem[number];
	for (int i = 0; i < number; i++)
		items[i] = new TreeItem(tree, 0);

	assertEquals(0, tree.getSelectionCount());
	tree.setSelection(new TreeItem[] {items[2], items[4], items[5], items[10]});

	assertEquals(4, tree.getSelectionCount());

	tree.deselectAll();
	assertEquals(0, tree.getSelectionCount());

	tree.selectAll();
	assertEquals(number, tree.getSelectionCount());

	tree.deselectAll();
	assertEquals(0, tree.getSelectionCount());
}

@Test
public void test_getColumnCount() {
	assertEquals(0, tree.getColumnCount());
	TreeColumn column0 = new TreeColumn(tree, SWT.NONE);
	assertEquals(1, tree.getColumnCount());
	TreeColumn column1 = new TreeColumn(tree, SWT.NONE);
	assertEquals(2, tree.getColumnCount());
	TreeColumn column2 = new TreeColumn(tree, SWT.NONE);
	assertEquals(3, tree.getColumnCount());
	column0.dispose();
	assertEquals(2, tree.getColumnCount());
	column1.dispose();
	assertEquals(1, tree.getColumnCount());
	column2.dispose();
	assertEquals(0, tree.getColumnCount());
}

@Test
public void test_getColumnI() {
	try {
		tree.getColumn(0);
		fail("No exception thrown for index out of range");
	}
	catch (IllegalArgumentException e) {
	}
	TreeColumn column0 = new TreeColumn(tree, SWT.LEFT);
	try {
		tree.getColumn(1);
		fail("No exception thrown for index out of range");
	}
	catch (IllegalArgumentException e) {
	}
	assertEquals(column0, tree.getColumn(0));
	TreeColumn column1 = new TreeColumn(tree, SWT.LEFT);
	assertEquals(column1, tree.getColumn(1));
	column1.dispose();
	try {
		tree.getColumn(1);
		fail("No exception thrown for index out of range");
	}
	catch (IllegalArgumentException e) {
	}
	column0.dispose();
	try {
		tree.getColumn(0);
		fail("No exception thrown for index out of range");
	}
	catch (IllegalArgumentException e) {
	}
}

@Test
public void test_getColumns() {
	assertEquals(0, tree.getColumns().length);
	TreeColumn column0 = new TreeColumn(tree, SWT.LEFT);
	TreeColumn[] columns = tree.getColumns();
	assertEquals(1, columns.length);
	assertEquals(column0, columns[0]);
	column0.dispose();
	assertEquals(0, tree.getColumns().length);
	column0 = new TreeColumn(tree, SWT.LEFT);
	TreeColumn column1 = new TreeColumn(tree, SWT.RIGHT, 1);
	columns = tree.getColumns();
	assertEquals(2, columns.length);
	assertEquals(column0, columns[0]);
	assertEquals(column1, columns[1]);
	column0.dispose();
	columns = tree.getColumns();
	assertEquals(1, columns.length);
	assertEquals(column1, columns[0]);
	column1.dispose();
	assertEquals(0, tree.getColumns().length);
}

@Test
public void test_getGridLineWidth() {
	tree.getGridLineWidth();
}

@Test
public void test_getHeaderHeight() {
	if (SwtTestUtil.isGTK) {
		//TODO Fix GTK failure.
		if (SwtTestUtil.verbose) {
			System.out.println("Excluded test_getHeaderHeight(org.eclipse.swt.tests.junit.Test_org_eclipse_swt_widgets_Tree)");
		}
		return;
	}
	assertEquals(0, tree.getHeaderHeight());
	tree.setHeaderVisible(true);
	assertTrue(tree.getHeaderHeight() > 0);
	tree.setHeaderVisible(false);
	assertEquals(0, tree.getHeaderHeight());
}

@Test
public void test_getItemHeight() {
	assertTrue(":a: Item height is 0", tree.getItemHeight() > 0);
	new TreeItem(tree, 0);
	assertTrue(":b: Item height is 0", tree.getItemHeight() > 0);
}

@Test
public void test_getItemI() {
	int number = 15;
	TreeItem[] items = new TreeItem[number];
	for (int i = 0; i < number; i++)
		items[i] = new TreeItem(tree, 0);

	for (int i = 0; i < number; i++)
		assertEquals("i=" + i, items[i], tree.getItem(i));
	try {
		tree.getItem(number);
		fail("No exception thrown for illegal index argument");
	}
	catch (IllegalArgumentException e) {
	}

	try {
		tree.getItem(number+1);
		fail("No exception thrown for illegal index argument");
	}
	catch (IllegalArgumentException e) {
	}

	try {
		tree.getItem(-1);
		fail("No exception thrown for illegal index argument");
	}
	catch (IllegalArgumentException e) {
	}
}

@Test
public void test_getItems() {
	int[] cases = {0, 10, 100};
	TreeItem [][] items = new TreeItem [cases.length][];
	for (int j = 0; j < cases.length; j++) {
		items [j] = new TreeItem [cases [j]];
	}
	for (int j = 0; j < cases.length; j++) {
		for (int i = 0; i < cases[j]; i++) {
			TreeItem ti = new TreeItem(tree, 0);
			items [j][i] = ti;
		}
		assertArrayEquals(items[j], tree.getItems());
		tree.removeAll();
		assertEquals(0, tree.getItemCount());
	}

	makeCleanEnvironment(false);

	for (int j = 0; j < cases.length; j++) {
		for (int i = 0; i < cases[j]; i++) {
			TreeItem ti = new TreeItem(tree, 0);
			ti.setText(String.valueOf(i));
		}
		TreeItem[] items2 = tree.getItems();
		for (int i = 0; i < items2.length; i++) {
			assertEquals(String.valueOf(i), items2[i].getText());
		}
		tree.removeAll();
		assertEquals(0, tree.getItemCount());
	}
}

@Test
public void test_getParentItem() {
	assertNull(tree.getParentItem());
}

@Test
public void test_getSelectionCount() {
	int number = 15;
	TreeItem[] items = new TreeItem[number];
	for (int i = 0; i < number; i++)
		items[i] = new TreeItem(tree, 0);

	assertEquals(0, tree.getSelectionCount());

	tree.setSelection(new TreeItem[]{items[2]});
	assertEquals(1, tree.getSelectionCount());

	tree.setSelection(new TreeItem[]{items[number-1]});
	assertEquals(1, tree.getSelectionCount());

	tree.setSelection(new TreeItem[]{items[10]});
	assertEquals(1, tree.getSelectionCount());

	tree.setSelection(new TreeItem[]{items[2], items[number-1], items[10]});
	assertEquals(3, tree.getSelectionCount());

	tree.setSelection(items);
	assertEquals(15, tree.getSelectionCount());

	tree.setSelection(new TreeItem[]{});
	assertEquals(0, tree.getSelectionCount());


	makeCleanEnvironment(true); // use single-selection tree.

	items = new TreeItem[number];
	for (int i = 0; i < number; i++)
		items[i] = new TreeItem(tree, 0);

	assertEquals(0, tree.getSelectionCount());

	tree.setSelection(new TreeItem[]{items[2]});
	assertEquals(1, tree.getSelectionCount());

	tree.setSelection(new TreeItem[]{items[number-1]});
	assertEquals(1, tree.getSelectionCount());

	tree.setSelection(new TreeItem[]{items[10]});
	assertEquals(1, tree.getSelectionCount());

	tree.setSelection(new TreeItem[]{items[2], items[number-1], items[10]});
	assertEquals(0, tree.getSelectionCount());

	tree.setSelection(items);
	assertEquals(0, tree.getSelectionCount());

	tree.setSelection(new TreeItem[]{});
	assertEquals(0, tree.getSelectionCount());
}

@Test
public void test_removeAll() {
	tree.removeAll();
	assertEquals(0, tree.getItemCount());

	int number = 20;
	TreeItem[] items = new TreeItem[number];
	for (int i = 0; i < number; i++) {
		items[i] = new TreeItem(tree, 0);
	}
	assertEquals(number, tree.getItemCount());

	tree.removeAll();
	assertEquals(0, tree.getItemCount());
}

@Test
public void test_selectAll() {
	int number = 5;
	TreeItem[] items = new TreeItem[number];
	for (int i = 0; i < number; i++)
		items[i] = new TreeItem(tree, 0);

	assertEquals(0, tree.getSelectionCount());
	tree.selectAll();
	assertEquals(number, tree.getSelectionCount());

	makeCleanEnvironment(true); // single-selection tree

	items = new TreeItem[number];
	for (int i = 0; i < number; i++)
		items[i] = new TreeItem(tree, 0);

	assertEquals(0, tree.getSelectionCount());
	tree.selectAll();
	assertEquals(0, tree.getSelectionCount());
}

@Test
public void test_setHeaderVisibleZ() {
	assertFalse(tree.getHeaderVisible());
	tree.setHeaderVisible(true);
	assertTrue(tree.getHeaderVisible());
	tree.setHeaderVisible(false);
	assertFalse(tree.getHeaderVisible());
}

@Test
public void test_setItemCountI() {
	tree.removeAll();
	assertEquals(0, tree.getItemCount());
	for (int i=0; i<8; i++) {
		new TreeItem(tree, SWT.NULL);
		assertEquals(i+1, tree.getItemCount());
	}
	assertEquals(8, tree.getItemCount());
	assertEquals(4, tree.indexOf(tree.getItems()[4]));
	tree.getItem(1).dispose();
	assertEquals(7, tree.getItemCount());
	new TreeItem (tree, SWT.NULL, 0);
	assertEquals(1, tree.indexOf(tree.getItems()[1]));
	assertEquals(8, tree.getItemCount());
	tree.removeAll();
	assertEquals(0, tree.getItemCount());
	tree.setItemCount(0);
	assertEquals(0, tree.getItemCount());
	tree.setItemCount(-1);
	assertEquals(0, tree.getItemCount());
	tree.setItemCount(10);
	assertEquals(10, tree.getItemCount());
	tree.getItem(1).dispose();
	assertEquals(9, tree.getItemCount());
	assertEquals(4, tree.indexOf(tree.getItems()[4]));
	tree.setItemCount(3);
	assertEquals(3, tree.getItemCount());
	try {
		tree.getItem(4);
		fail("No exception thrown for illegal index argument");
	}
	catch (IllegalArgumentException e) {
	}
	tree.setItemCount(40);
	assertEquals(40, tree.getItemCount());
	tree.getItem(39);
}

@Test
public void test_setLinesVisibleZ() {
	assertFalse(tree.getLinesVisible());
	tree.setLinesVisible(true);
	assertTrue(tree.getLinesVisible());
	tree.setLinesVisible(false);
	assertFalse(tree.getLinesVisible());
}

@Override
@Test
public void test_setRedrawZ() {
}

@Test
public void test_setSelection$Lorg_eclipse_swt_widgets_TreeItem() {
	int number = 20;
	TreeItem[] items = new TreeItem[number];
	for (int i = 0; i < number; i++) {
		items[i] = new TreeItem(tree, 0);
	}

	assertArrayEquals(new TreeItem[] {}, tree.getSelection());

	tree.setSelection(new TreeItem[] {items[5], items[16], items[19]});
	assertArrayEquals(new TreeItem[] {items[5], items[16], items[19]}, tree.getSelection());

	tree.setSelection(items);
	assertArrayEquals(items, tree.getSelection());

	tree.setSelection(tree.getItems());
	assertArrayEquals(tree.getItems(), tree.getSelection());

	tree.setSelection(new TreeItem[] {});
	assertArrayEquals(new TreeItem[] {}, tree.getSelection());
	assertEquals(0, tree.getSelectionCount());

	try {
		tree.setSelection((TreeItem[]) null);
		fail("No exception thrown for items == null");
	}
	catch (IllegalArgumentException e) {
	}

	tree.setSelection(new TreeItem[]{null});
	assertEquals(0, tree.getSelectionCount());

	tree.setSelection(new TreeItem[]{items[10]});
	assertArrayEquals(new TreeItem[] {items[10]}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[number-1]});
	assertArrayEquals(new TreeItem[] {items[number-1]}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[2]});
	assertArrayEquals(new TreeItem[] {items[2]}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[10], items[number-1], items[2]});
	assertArrayEquals(new TreeItem[] {items[2], items[10], items[number - 1]}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[0], items[3], items[2]});
	assertArrayEquals(new TreeItem[]{items[0], items[2], items[3]}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[3], items[2], items[1]});
	assertArrayEquals(new TreeItem[]{items[1], items[2], items[3]}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[1], items[4], items[0]});
	assertArrayEquals(new TreeItem[]{items[0], items[1], items[4]}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[0], items[4], items[0]});
	assertArrayEquals(new TreeItem[]{items[0], items[4]}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[2], items[3], items[4]});
	assertArrayEquals(new TreeItem[]{items[2], items[3], items[4]}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[4], items[4], items[4], items[4], items[4], items[4]});
	assertArrayEquals(new TreeItem[]{items[4]}, tree.getSelection());

	tree.setSelection(new TreeItem[] {items[0]});
	assertArrayEquals(new TreeItem[] {items[0]}, tree.getSelection());

	tree.setSelection(new TreeItem[] {items[3]});
	assertArrayEquals(new TreeItem[] {items[3]}, tree.getSelection());

	tree.setSelection(new TreeItem[] {items[4]});
	assertArrayEquals(new TreeItem[] {items[4]}, tree.getSelection());

	tree.setSelection(new TreeItem[] {items[2]});
	assertArrayEquals(new TreeItem[] {items[2]}, tree.getSelection());

	tree.setSelection(new TreeItem[] {items[1]});
	assertArrayEquals(new TreeItem[] {items[1]}, tree.getSelection());

	tree.removeAll();
	tree.setSelection(new TreeItem[] {});
	assertArrayEquals(new TreeItem[] {}, tree.getSelection());


	makeCleanEnvironment(true); // single-selection tree

	items = new TreeItem[number];
	for (int i = 0; i < number; i++)
		items[i] = new TreeItem(tree, 0);

	assertArrayEquals(new TreeItem[] {}, tree.getSelection());

	tree.setSelection(new TreeItem[] {items[5], items[16], items[19]});
	assertArrayEquals(new TreeItem[] {}, tree.getSelection());

	tree.setSelection(items);
	assertArrayEquals(new TreeItem[] {}, tree.getSelection());

	tree.setSelection(tree.getItems());
	assertArrayEquals(new TreeItem[] {}, tree.getSelection());

	tree.setSelection(new TreeItem[] {});
	assertArrayEquals(new TreeItem[] {}, tree.getSelection());
	assertEquals(0, tree.getSelectionCount());

	try {
		tree.setSelection((TreeItem[]) null);
		fail("No exception thrown for items == null");
	}
	catch (IllegalArgumentException e) {
	}

	tree.setSelection(new TreeItem[]{items[10]});
	assertArrayEquals(new TreeItem[] {items[10]}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[number-1]});
	assertArrayEquals(new TreeItem[] {items[number-1]}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[2]});
	assertArrayEquals(new TreeItem[] {items[2]}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[10], items[number-1], items[2]});
	assertArrayEquals(new TreeItem[] {}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[0], items[3], items[2]});
	assertArrayEquals(new TreeItem[]{}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[3], items[2], items[1]});
	assertArrayEquals(new TreeItem[]{}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[1], items[4], items[0]});
	assertArrayEquals(new TreeItem[]{}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[0], items[4], items[0]});
	assertArrayEquals(new TreeItem[]{}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[2], items[3], items[4]});
	assertArrayEquals(new TreeItem[]{}, tree.getSelection());

	tree.setSelection(new TreeItem[]{items[4], items[4], items[4], items[4], items[4], items[4]});
	assertArrayEquals(new TreeItem[]{}, tree.getSelection());

	tree.setSelection(new TreeItem[] {items[0]});
	assertArrayEquals(new TreeItem[] {items[0]}, tree.getSelection());

	tree.setSelection(new TreeItem[] {items[3]});
	assertArrayEquals(new TreeItem[] {items[3]}, tree.getSelection());

	tree.setSelection(new TreeItem[] {items[4]});
	assertArrayEquals(new TreeItem[] {items[4]}, tree.getSelection());

	tree.setSelection(new TreeItem[] {items[2]});
	assertArrayEquals(new TreeItem[] {items[2]}, tree.getSelection());

	tree.setSelection(new TreeItem[] {items[1]});
	assertArrayEquals(new TreeItem[] {items[1]}, tree.getSelection());

	tree.removeAll();
	tree.setSelection(new TreeItem[] {});
	assertArrayEquals(new TreeItem[] {}, tree.getSelection());
}

@Test
public void test_setTopItemLorg_eclipse_swt_widgets_TreeItem() {
	tree.removeAll();
	for (int i = 0; i < 10; i++) {
		new TreeItem(tree, 0);
	}
	TreeItem top = new TreeItem(tree, 0);
	for (int i = 0; i < 10; i++) {
		new TreeItem(tree, 0);
	}
	tree.setSize(50,50);
	shell.open();
	tree.setTopItem(top);
	for (int i = 0; i < 10; i++) {
		new TreeItem(tree, 0);
	}
	TreeItem top2 = tree.getTopItem();
	shell.setVisible(false);
	assertEquals(top, top2);
	try {
		shell.setVisible(true);
		tree.setTopItem(null);
		fail("No exception thrown for item == null");
	} catch (IllegalArgumentException e) {
	} finally {
		shell.setVisible (false);
	}
}

@Test
public void test_showItemLorg_eclipse_swt_widgets_TreeItem() {
	try {
		tree.showItem(null);
		fail("No exception thrown for item == null");
	}
	catch (IllegalArgumentException e) {
	}

	int number = 20;
	TreeItem[] items = new TreeItem[number];
	for (int i = 0; i < number; i++) {
		items[i] = new TreeItem(tree, 0);
	}
	for(int i=0; i<number; i++)
		tree.showItem(items[i]);

	tree.removeAll();

	makeCleanEnvironment(false);
	//showing somebody else's items

	items = new TreeItem[number];
	for (int i = 0; i < number; i++) {
		items[i] = new TreeItem(tree, 0);
	}

	Tree tree2 = new Tree(shell, 0);
	TreeItem[] items2 = new TreeItem[number];
	for (int i = 0; i < number; i++) {
		items2[i] = new TreeItem(tree2, 0);
	}

	for(int i=0; i<number; i++)
		tree.showItem(items2[i]);

	tree.removeAll();
}

@Test
public void test_showSelection() {
	TreeItem item;

	tree.showSelection();
	item = new TreeItem(tree, 0);
	tree.setSelection(new TreeItem[]{item});
	tree.showSelection();
}

/* custom */
public Tree tree;

/**
 * Clean up the environment for a new test.
 *
 * @param single true if the new tree should be a single-selection one,
 * otherwise use multi-selection.
 */
private void makeCleanEnvironment(boolean single) {
// this method must be private or protected so the auto-gen tool keeps it
	if (tree != null) tree.dispose();
	tree = new Tree(shell, single?SWT.SINGLE:SWT.MULTI);
	setWidget(tree);
}

private void createTree(List<String> events) {
    makeCleanEnvironment(true);
	for (int i = 0; i < 3; i++) {
		TreeItem item = new TreeItem(tree, SWT.NONE);
		item.setText("TreeItem" + i);
		for (int j = 0; j < 4; j++) {
			TreeItem ti = new TreeItem(item, SWT.NONE);
			ti.setText("TreeItem" + i + j);
			hookExpectedEvents(ti, getTestName(), events);
		}
		hookExpectedEvents(item, getTestName(), events);
	}
}

@Test
public void test_consistency_KeySelection() {
    List<String> events = new ArrayList<>();
    createTree(events);
    consistencyEvent(0, SWT.ARROW_DOWN, 0, 0, ConsistencyUtility.KEY_PRESS, events);
}

@Test
public void test_consistency_MouseSelection() {
    List<String> events = new ArrayList<>();
    createTree(events);
    consistencyEvent(30, 30, 1, 0, ConsistencyUtility.MOUSE_CLICK, events);
}

@Test
public void test_consistency_MouseExpand() {
    List<String> events = new ArrayList<>();
    createTree(events);
    consistencyEvent(11, 10, 1, 0, ConsistencyUtility.MOUSE_CLICK, events);
}

@Test
public void test_consistency_KeyExpand() {
    List<String> events = new ArrayList<>();
    createTree(events);
    int code=SWT.ARROW_RIGHT;
    if(SwtTestUtil.isGTK)
        code = SWT.KEYPAD_ADD;
    consistencyEvent(0, code, 0, 0, ConsistencyUtility.KEY_PRESS, events);
}

@Test
public void test_consistency_DoubleClick () {
    List<String> events = new ArrayList<>();
    createTree(events);
    consistencyPrePackShell();
    consistencyEvent(20, tree.getItemHeight()*2, 1, 0,
            	     ConsistencyUtility.MOUSE_DOUBLECLICK, events);
}

@Test
public void test_consistency_EnterSelection () {
    List<String> events = new ArrayList<>();
    createTree(events);
    consistencyEvent(13, 10, 0, 0, ConsistencyUtility.KEY_PRESS, events);
}

@Test
public void test_consistency_SpaceSelection () {
    List<String> events = new ArrayList<>();
    createTree(events);
    consistencyEvent(' ', 32, 0, 0, ConsistencyUtility.KEY_PRESS, events);
}

@Test
public void test_consistency_MenuDetect () {
    List<String> events = new ArrayList<>();
    createTree(events);
    consistencyEvent(50, 25, 3, 0, ConsistencyUtility.MOUSE_CLICK, events);
}

@Test
public void test_consistency_DragDetect () {
    List<String> events = new ArrayList<>();
    createTree(events);
    consistencyEvent(30, 20, 50, 30, ConsistencyUtility.MOUSE_DRAG, events);
}

@Test
public void test_Virtual() {
	tree.dispose();
	tree = new Tree(shell, SWT.VIRTUAL | SWT.BORDER);
	setWidget(tree);

	int count = 10000;
	int visibleCount = 10;

	shell.setLayout(new FillLayout());
	final TreeItem[] top = { null };
	final int[] dataCounter = { 0 };
	tree.addListener(SWT.SetData, event -> {
		TreeItem item = (TreeItem) event.item;
		if (item.getParentItem() == null) {
			top[0] = item;
			item.setText("top");
		} else {
			int index = top[0].indexOf(item);
			item.setText("Item " + index);
		}
		dataCounter[0]++;
	});

	tree.setItemCount(1);
	shell.setSize (200, tree.getItemHeight() * visibleCount);
	shell.open ();
	TreeItem item0 = tree.getItem(0);
	item0.setItemCount(count);
	item0.setExpanded(true);
	long end = System.currentTimeMillis() + 3000;
	while (!shell.isDisposed() && System.currentTimeMillis() < end) {
		if (!shell.getDisplay().readAndDispatch ()) {
			try {
				Thread.sleep(10);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}
	// the "* 2" allows some surplus for platforms that pre-fetch items to improve scrolling performance:
	assertTrue("SetData callback count not in range: " + dataCounter[0],
			dataCounter[0] > visibleCount / 2 && dataCounter[0] <= visibleCount * 2);
}
}