Add unit test for SkippingIterator, fix bug.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/collections/trunk@1682188 13f79535-47bb-0310-9956-ffa450edef68

src/main/java/org/apache/commons/collections4/iterators/SkippingIterator.java

@@ -23,7 +23,7 @@ import java.util.Iterator;
  * before that position.
  *
  * @since 4.1
- * @version $Id: $
+ * @version $Id$
  */
 public class SkippingIterator<E> extends AbstractIteratorDecorator<E> {
 
@@ -64,7 +64,6 @@ public class SkippingIterator<E> extends AbstractIteratorDecorator<E> {
     private void init() {
         while (pos < offset && hasNext()) {
             next();
-            pos++;
         }
     }
 

src/test/java/org/apache/commons/collections4/iterators/SkippingIteratorTest.java

@@ -0,0 +1,300 @@
+/*
+ * 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.iterators;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
+
+import org.junit.Test;
+
+/**
+ * A unit test to test the basic functions of {@link SkippingIterator}.
+ *
+ * @version $Id$
+ */
+public class SkippingIteratorTest<E> extends AbstractIteratorTest<E> {
+
+    /** Test array of size 7 */
+    private String[] testArray = {
+        "a", "b", "c", "d", "e", "f", "g"
+    };
+
+    private List<E> testList;
+
+    public SkippingIteratorTest(final String testName) {
+        super(testName);
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public void setUp()
+        throws Exception {
+        super.setUp();
+        testList = Arrays.asList((E[]) testArray);
+    }
+
+    @Override
+    public Iterator<E> makeEmptyIterator() {
+        return new SkippingIterator<E>(Collections.<E>emptyList().iterator(), 0);
+    }
+
+    @Override
+    public Iterator<E> makeObject() {
+        return new SkippingIterator<E>(new ArrayList<E>(testList).iterator(), 1);
+    }
+
+    // ---------------- Tests ---------------------
+
+    /**
+     * Test a decorated iterator bounded such that the first element returned is
+     * at an index greater its first element, and the last element returned is
+     * at an index less than its last element.
+     */
+    @Test
+    public void testSkipping() {
+        Iterator<E> iter = new SkippingIterator<E>(testList.iterator(), 2);
+
+        assertTrue(iter.hasNext());
+        assertEquals("c", iter.next());
+        assertTrue(iter.hasNext());
+        assertEquals("d", iter.next());
+        assertTrue(iter.hasNext());
+        assertEquals("e", iter.next());
+        assertTrue(iter.hasNext());
+        assertEquals("f", iter.next());
+        assertTrue(iter.hasNext());
+        assertEquals("g", iter.next());
+
+        assertFalse(iter.hasNext());
+        try {
+            iter.next();
+            fail("Expected NoSuchElementException.");
+        } catch (NoSuchElementException nsee) { /* Success case */
+        }
+    }
+
+    /**
+     * Test a decorated iterator bounded such that the <code>offset</code> is
+     * zero, in that the SkippingIterator should return all the same elements
+     * as its decorated iterator.
+     */
+    @Test
+    public void testSameAsDecorated() {
+        Iterator<E> iter = new SkippingIterator<E>(testList.iterator(), 0);
+
+        assertTrue(iter.hasNext());
+        assertEquals("a", iter.next());
+        assertTrue(iter.hasNext());
+        assertEquals("b", iter.next());
+        assertTrue(iter.hasNext());
+        assertEquals("c", iter.next());
+        assertTrue(iter.hasNext());
+        assertEquals("d", iter.next());
+        assertTrue(iter.hasNext());
+        assertEquals("e", iter.next());
+        assertTrue(iter.hasNext());
+        assertEquals("f", iter.next());
+        assertTrue(iter.hasNext());
+        assertEquals("g", iter.next());
+
+        assertFalse(iter.hasNext());
+        try {
+            iter.next();
+            fail("Expected NoSuchElementException.");
+        } catch (NoSuchElementException nsee) { /* Success case */
+        }
+    }
+
+    /**
+     * Test the case if the <code>offset</code> passed to the constructor is
+     * greater than the decorated iterator's size. The SkippingIterator should
+     * behave as if there are no more elements to return.
+     */
+    @Test
+    public void testOffsetGreaterThanSize() {
+        Iterator<E> iter = new SkippingIterator<E>(testList.iterator(), 10);
+        assertFalse(iter.hasNext());
+        try {
+            iter.next();
+            fail("Expected NoSuchElementException.");
+        } catch (NoSuchElementException nsee) { /* Success case */
+        }
+    }
+
+    /**
+     * Test the case if a negative <code>offset</code> is passed to the
+     * constructor. {@link IllegalArgumentException} is expected.
+     */
+    @Test
+    public void testNegativeOffset() {
+        try {
+            new SkippingIterator<E>(testList.iterator(), -1);
+            fail("Expected IllegalArgumentException.");
+        } catch (IllegalArgumentException iae) { /* Success case */
+        }
+    }
+
+    /**
+     * Test the <code>remove()</code> method being called without
+     * <code>next()</code> being called first.
+     */
+    @Test
+    public void testRemoveWithoutCallingNext() {
+        List<E> testListCopy = new ArrayList<E>(testList);
+        Iterator<E> iter = new SkippingIterator<E>(testListCopy.iterator(), 1);
+
+        try {
+            iter.remove();
+            fail("Expected IllegalStateException.");
+        } catch (IllegalStateException ise) { /* Success case */
+        }
+    }
+
+    /**
+     * Test the <code>remove()</code> method being called twice without calling
+     * <code>next()</code> in between.
+     */
+    @Test
+    public void testRemoveCalledTwice() {
+        List<E> testListCopy = new ArrayList<E>(testList);
+        Iterator<E> iter = new SkippingIterator<E>(testListCopy.iterator(), 1);
+
+        assertTrue(iter.hasNext());
+        assertEquals("b", iter.next());
+        iter.remove();
+
+        try {
+            iter.remove();
+            fail("Expected IllegalStateException.");
+        } catch (IllegalStateException ise) { /* Success case */
+        }
+    }
+
+    /**
+     * Test removing the first element. Verify that the element is removed from
+     * the underlying collection.
+     */
+    @Test
+    public void testRemoveFirst() {
+        List<E> testListCopy = new ArrayList<E>(testList);
+        Iterator<E> iter = new SkippingIterator<E>(testListCopy.iterator(), 4);
+
+        assertTrue(iter.hasNext());
+        assertEquals("e", iter.next());
+
+        iter.remove();
+        assertFalse(testListCopy.contains("e"));
+
+        assertTrue(iter.hasNext());
+        assertEquals("f", iter.next());
+        assertTrue(iter.hasNext());
+        assertEquals("g", iter.next());
+
+        assertFalse(iter.hasNext());
+        try {
+            iter.next();
+            fail("Expected NoSuchElementException.");
+        } catch (NoSuchElementException nsee) { /* Success case */
+        }
+    }
+
+    /**
+     * Test removing an element in the middle of the iterator. Verify that the
+     * element is removed from the underlying collection.
+     */
+    @Test
+    public void testRemoveMiddle() {
+        List<E> testListCopy = new ArrayList<E>(testList);
+        Iterator<E> iter = new SkippingIterator<E>(testListCopy.iterator(), 3);
+
+        assertTrue(iter.hasNext());
+        assertEquals("d", iter.next());
+
+        iter.remove();
+        assertFalse(testListCopy.contains("d"));
+
+        assertTrue(iter.hasNext());
+        assertEquals("e", iter.next());
+        assertTrue(iter.hasNext());
+        assertEquals("f", iter.next());
+        assertTrue(iter.hasNext());
+        assertEquals("g", iter.next());
+
+        assertFalse(iter.hasNext());
+        try {
+            iter.next();
+            fail("Expected NoSuchElementException.");
+        } catch (NoSuchElementException nsee) { /* Success case */
+        }
+    }
+
+    /**
+     * Test removing the last element. Verify that the element is removed from
+     * the underlying collection.
+     */
+    @Test
+    public void testRemoveLast() {
+        List<E> testListCopy = new ArrayList<E>(testList);
+        Iterator<E> iter = new SkippingIterator<E>(testListCopy.iterator(), 5);
+
+        assertTrue(iter.hasNext());
+        assertEquals("f", iter.next());
+        assertTrue(iter.hasNext());
+        assertEquals("g", iter.next());
+
+        assertFalse(iter.hasNext());
+        try {
+            iter.next();
+            fail("Expected NoSuchElementException.");
+        } catch (NoSuchElementException nsee) { /* Success case */
+        }
+
+        iter.remove();
+        assertFalse(testListCopy.contains("g"));
+
+        assertFalse(iter.hasNext());
+        try {
+            iter.next();
+            fail("Expected NoSuchElementException.");
+        } catch (NoSuchElementException nsee) { /* Success case */
+        }
+    }
+
+    /**
+     * Test the case if the decorated iterator does not support the
+     * <code>remove()</code> method and throws an {@link UnsupportedOperationException}.
+     */
+    @Test
+    public void testRemoveUnsupported() {
+        Iterator<E> mockIterator = new AbstractIteratorDecorator<E>(testList.iterator()) {
+            @Override
+            public void remove() {
+                throw new UnsupportedOperationException();
+            }
+        };
+
+        Iterator<E> iter = new SkippingIterator<E>(mockIterator, 1);
+        assertTrue(iter.hasNext());
+        assertEquals("b", iter.next());
+        try {
+            iter.remove();
+            fail("Expected UnsupportedOperationException.");
+        } catch (UnsupportedOperationException usoe) { /* Success case */
+        }
+    }
+}