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Guava testlib is a set of java classes used for more convenient unit testing - particularly to assist the tests for Guava itself.
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/*
 * Copyright (C) 2008 The Guava Authors
 *
 * Licensed 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 com.google.common.collect.testing.testers;

import static com.google.common.collect.testing.IteratorFeature.MODIFIABLE;
import static com.google.common.collect.testing.IteratorFeature.UNMODIFIABLE;
import static com.google.common.collect.testing.features.CollectionFeature.KNOWN_ORDER;
import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_REMOVE;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.collect.testing.AbstractCollectionTester;
import com.google.common.collect.testing.Helpers;
import com.google.common.collect.testing.IteratorFeature;
import com.google.common.collect.testing.IteratorTester;
import com.google.common.collect.testing.features.CollectionFeature;

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.CopyOnWriteArraySet;

/**
 * A generic JUnit test which tests {@code iterator} operations on a collection.
 * Can't be invoked directly; please see
 * {@link com.google.common.collect.testing.CollectionTestSuiteBuilder}.
 *
 * This class is GWT compatible.
 *
 * @author Chris Povirk
 */
@GwtCompatible(emulated = true)
public class CollectionIteratorTester extends AbstractCollectionTester {
  public void testIterator() {
    List iteratorElements = new ArrayList();
    for (E element : collection) { // uses iterator()
      iteratorElements.add(element);
    }
    Helpers.assertEqualIgnoringOrder(
        Arrays.asList(createSamplesArray()), iteratorElements);
  }

  @CollectionFeature.Require(KNOWN_ORDER)
  public void testIterationOrdering() {
    List iteratorElements = new ArrayList();
    for (E element : collection) { // uses iterator()
      iteratorElements.add(element);
    }
    List expected = Helpers.copyToList(getOrderedElements());
    assertEquals("Different ordered iteration", expected, iteratorElements);
  }

  // TODO: switch to DerivedIteratorTestSuiteBuilder

  @CollectionFeature.Require({KNOWN_ORDER, SUPPORTS_REMOVE})
  public void testIterator_knownOrderRemoveSupported() {
    runIteratorTest(MODIFIABLE, IteratorTester.KnownOrder.KNOWN_ORDER,
        getOrderedElements());
  }

  @CollectionFeature.Require(value = KNOWN_ORDER, absent = SUPPORTS_REMOVE)
  public void testIterator_knownOrderRemoveUnsupported() {
    runIteratorTest(UNMODIFIABLE, IteratorTester.KnownOrder.KNOWN_ORDER,
        getOrderedElements());
  }

  @CollectionFeature.Require(absent = KNOWN_ORDER, value = SUPPORTS_REMOVE)
  public void testIterator_unknownOrderRemoveSupported() {
    runIteratorTest(MODIFIABLE, IteratorTester.KnownOrder.UNKNOWN_ORDER,
        getSampleElements());
  }

  @CollectionFeature.Require(absent = {KNOWN_ORDER, SUPPORTS_REMOVE})
  public void testIterator_unknownOrderRemoveUnsupported() {
    runIteratorTest(UNMODIFIABLE, IteratorTester.KnownOrder.UNKNOWN_ORDER,
        getSampleElements());
  }

  private void runIteratorTest(Set features,
      IteratorTester.KnownOrder knownOrder, Iterable elements) {
    new IteratorTester(Platform.collectionIteratorTesterNumIterations(), features, elements,
        knownOrder) {
      {
        // TODO: don't set this universally
        ignoreSunJavaBug6529795();
      }

      @Override protected Iterator newTargetIterator() {
        resetCollection();
        return collection.iterator();
      }

      @Override protected void verify(List elements) {
        expectContents(elements);
      }
    }.test();
  }

  /**
   * Returns the {@link Method} instance for
   * {@link #testIterator_knownOrderRemoveSupported()} so that tests of
   * {@link CopyOnWriteArraySet} and {@link CopyOnWriteArrayList} can suppress
   * it with {@code FeatureSpecificTestSuiteBuilder.suppressing()} until Sun bug
   * 6570575 is fixed.
   */
  @GwtIncompatible("reflection")
  public static Method getIteratorKnownOrderRemoveSupportedMethod() {
    return Helpers.getMethod(
          CollectionIteratorTester.class, "testIterator_knownOrderRemoveSupported");
  }

  /**
   * Returns the {@link Method} instance for
   * {@link #testIterator_unknownOrderRemoveSupported()} so that tests of
   * classes with unmodifiable iterators can suppress it.
   */
  @GwtIncompatible("reflection")
  public static Method getIteratorUnknownOrderRemoveSupportedMethod() {
    return Helpers.getMethod(
        CollectionIteratorTester.class, "testIterator_unknownOrderRemoveSupported");
  }

  public void testIteratorNoSuchElementException() {
    Iterator iterator = collection.iterator();
    while (iterator.hasNext()) {
      iterator.next();
    }

    try {
      iterator.next();
      fail("iterator.next() should throw NoSuchElementException");
    } catch (NoSuchElementException expected) {}
  }

  /**
   * Returns the {@link Method} instance for
   * {@link #testIterator_knownOrderRemoveUnsupported()} so that tests of
   * {@code ArrayStack} can suppress it with
   * {@code FeatureSpecificTestSuiteBuilder.suppressing()}. {@code ArrayStack}
   * supports {@code remove()} on only the first element, and the iterator
   * tester can't handle that.
   */
  @GwtIncompatible("reflection")
  public static Method getIteratorKnownOrderRemoveUnsupportedMethod() {
    return Helpers.getMethod(
        CollectionIteratorTester.class, "testIterator_knownOrderRemoveUnsupported");
  }
}