test/org/apache/tomcat/util/collections/TestSynchronizedStack.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.tomcat.util.collections;

import org.junit.Assert;
import org.junit.Test;

public class TestSynchronizedStack {

    @Test
    public void testPopEmpty() {
        SynchronizedStack<Object> stack = new SynchronizedStack<>();
        Assert.assertNull(stack.pop());
    }

    @Test
    public void testPushPopOrder() {
        SynchronizedStack<Object> stack = new SynchronizedStack<>();

        Object o1 = new Object();
        Object o2 = new Object();
        Object o3 = new Object();
        Object o4 = new Object();

        stack.push(o1);
        stack.push(o2);
        stack.push(o3);
        stack.push(o4);

        Assert.assertSame(stack.pop(), o4);
        Assert.assertSame(stack.pop(), o3);
        Assert.assertSame(stack.pop(), o2);
        Assert.assertSame(stack.pop(), o1);

        Assert.assertNull(stack.pop());
    }

    @Test
    public void testExpandPushPopOrder() {
        SynchronizedStack<Object> stack = new SynchronizedStack<>();

        Object o1 = new Object();
        Object o2 = new Object();
        Object o3 = new Object();
        Object o4 = new Object();

        for (int i = 0; i < 300; i++) {
            stack.push(o1);
            stack.push(o2);
            stack.push(o3);
            stack.push(o4);
        }

        for (int i = 0; i < 300; i++) {
            Assert.assertSame(stack.pop(), o4);
            Assert.assertSame(stack.pop(), o3);
            Assert.assertSame(stack.pop(), o2);
            Assert.assertSame(stack.pop(), o1);
        }

        Assert.assertNull(stack.pop());
    }

    @Test
    public void testLimit() {
        SynchronizedStack<Object> stack = new SynchronizedStack<>(2,2);

        Object o1 = new Object();
        Object o2 = new Object();
        Object o3 = new Object();
        Object o4 = new Object();

        stack.push(o1);
        stack.push(o2);
        stack.push(o3);
        stack.push(o4);

        Assert.assertSame(stack.pop(), o2);
        Assert.assertSame(stack.pop(), o1);

        Assert.assertNull(stack.pop());
    }


    @Test
    public void testLimitExpand() {
        SynchronizedStack<Object> stack = new SynchronizedStack<>(1,3);

        Object o1 = new Object();
        Object o2 = new Object();
        Object o3 = new Object();
        Object o4 = new Object();

        stack.push(o1);
        stack.push(o2);
        stack.push(o3);
        stack.push(o4);

        Assert.assertSame(stack.pop(), o3);
        Assert.assertSame(stack.pop(), o2);
        Assert.assertSame(stack.pop(), o1);

        Assert.assertNull(stack.pop());
    }
}