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

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+/*
+ * 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());
+    }
+}