[COLLECTIONS-758] Add test cases for AbstractQueueDecorator.

src/test/java/org/apache/commons/collections4/queue/QueueDecoratorTest.java

@@ -0,0 +1,223 @@
+/*
+ * 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.commons.collections4.queue;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.apache.commons.collections4.collection.AbstractCollectionTest;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.LinkedList;
+import java.util.Collection;
+import java.util.Queue;
+import java.util.NoSuchElementException;
+
+/**
+ * Test cases for AbstractQueueDecorator.
+ *
+ * @since 4.5
+ */
+public class QueueDecoratorTest<E> extends AbstractCollectionTest<E> {
+    /**
+     * JUnit constructor.
+     *
+     * @param testName the test class name
+     */
+    public QueueDecoratorTest(String testName) {
+        super(testName);
+    }
+
+    @Override
+    public Collection<E> makeConfirmedCollection() {
+        return new ArrayList<>();
+    }
+
+    @Override
+    public Collection<E> makeConfirmedFullCollection() {
+        final ArrayList<E> list = new ArrayList<>();
+        list.addAll(Arrays.asList(getFullElements()));
+        return list;
+    }
+
+    @Override
+    public Queue<E> makeObject() {
+        return new QueueDecorator<E>( new LinkedList<E>());
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public Queue<E> makeFullCollection() {
+        final Queue<E> queue = makeObject();
+        queue.addAll(Arrays.asList(getFullElements()));
+        return queue;
+    }
+
+    /**
+     * @return the collection field as a Queue
+     */
+    @Override
+    public Queue<E> getCollection() {
+        return (Queue<E>) super.getCollection();
+    }
+
+    /**
+     *  Tests {@link AbstractQueueDecorator#offer(Object)}.
+     */
+    public void testAbstractQueueDecoratorOffer() {
+        if (!isAddSupported()) {
+            return;
+        }
+        final E[] elements = getFullElements();
+        for (final E element : elements) {
+            resetEmpty();
+            final boolean r = getCollection().offer(element);
+            getConfirmed().add(element);
+            verify();
+            assertTrue("Empty queue changed after add", r);
+            assertEquals("Queue size is 1 after first add", 1, getCollection().size());
+        }
+
+        resetEmpty();
+        int size = 0;
+        for (final E element : elements) {
+            final boolean r = getCollection().offer(element);
+            getConfirmed().add(element);
+            verify();
+            if (r) {
+                size++;
+            }
+            assertEquals("Queue size should grow after add", size, getCollection().size());
+            assertTrue("Queue should contain added element", getCollection().contains(element));
+        }
+    }
+
+    /**
+     *  Tests {@link AbstractQueueDecorator#poll()}.
+     */
+    public void testAbstractQueueDecoratorPoll() {
+        if (!isRemoveSupported()) {
+            return;
+        }
+
+        resetEmpty();
+
+        E element = getCollection().poll();
+        assertNull(element);
+
+        resetFull();
+
+        final int max = getFullElements().length;
+        for (int i = 0; i < max; i++) {
+            element = getCollection().poll();
+            final boolean success = getConfirmed().remove(element);
+            assertTrue("poll should return correct element", success);
+            verify();
+        }
+
+        element = getCollection().poll();
+        assertNull(element);
+    }
+
+    /**
+     *  Tests {@link AbstractQueueDecorator#peek()}.
+     */
+    public void testAbstractQueueDecoratorPeek() {
+        if (!isRemoveSupported()) {
+            return;
+        }
+
+        resetEmpty();
+
+        E element = getCollection().peek();
+        assertNull(element);
+
+        resetFull();
+
+        final int max = getFullElements().length;
+        for (int i = 0; i < max; i++) {
+            element = getCollection().peek();
+
+            if (!isNullSupported()) {
+                assertNotNull(element);
+            }
+
+            assertTrue(getConfirmed().contains(element));
+
+            getCollection().remove(element);
+            getConfirmed().remove(element);
+
+            verify();
+        }
+
+        element = getCollection().peek();
+        assertNull(element);
+    }
+
+    /**
+     *  Tests {@link AbstractQueueDecorator#remove()}.
+     */
+    public void testAbstractQueueDecoratorRemove() {
+        if (!isRemoveSupported()) {
+            return;
+        }
+
+        resetEmpty();
+
+        Exception exception = assertThrows(NoSuchElementException.class, () -> {
+            getCollection().remove();
+        });
+        assertNull(exception.getMessage());
+
+        resetFull();
+
+        final int max = getFullElements().length;
+        for (int i = 0; i < max; i++) {
+            final E element = getCollection().remove();
+            final boolean success = getConfirmed().remove(element);
+            assertTrue("remove should return correct element", success);
+            verify();
+        }
+
+        Exception noSuchElementException = assertThrows(NoSuchElementException.class, () -> {
+            getCollection().element();
+        });
+        assertNull(noSuchElementException.getMessage());
+    }
+
+    public void testCreate() throws Exception {
+        resetEmpty();
+        writeExternalFormToDisk((java.io.Serializable) getCollection(), "src/test/resources/data/test/QueueDecorator.emptyCollection.version4.obj");
+        resetFull();
+        writeExternalFormToDisk((java.io.Serializable) getCollection(), "src/test/resources/data/test/QueueDecorator.fullCollection.version4.obj");
+    }
+
+}
+
+class QueueDecorator<E> extends AbstractQueueDecorator<E> {
+    /**
+     * Constructor that wraps (not copies).
+     *
+     * @param queue  the queue to decorate, must not be null
+     * @throws NullPointerException if queue is null
+     */
+    protected QueueDecorator(final Queue<E> queue) {
+        super(queue);
+    }
+}