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Java example source code file (AbstractSequentialIteratorTest.java)

This example Java source code file (AbstractSequentialIteratorTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

abstractsequentialiterator, assertionfailederror, gwtcompatible, integer, iterable, iterator, iteratortester, myexception, object, override, too, unmodifiable, unsupportedoperationexception, unused, util

The AbstractSequentialIteratorTest.java Java example source code

/*
 * Copyright (C) 2010 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;

import static com.google.common.collect.testing.IteratorFeature.UNMODIFIABLE;
import static com.google.common.truth.Truth.assertThat;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.collect.testing.IteratorTester;

import junit.framework.AssertionFailedError;
import junit.framework.TestCase;

import java.util.Iterator;
import java.util.NoSuchElementException;

/** Tests for {@link AbstractSequentialIterator}. */
@GwtCompatible(emulated = true)
public class AbstractSequentialIteratorTest extends TestCase {
  @GwtIncompatible // Too slow
  public void testDoublerExhaustive() {
    new IteratorTester<Integer>(3, UNMODIFIABLE, ImmutableList.of(1, 2),
        IteratorTester.KnownOrder.KNOWN_ORDER) {
      @Override
      protected Iterator<Integer> newTargetIterator() {
        return newDoubler(1, 2);
      }
    }.test();
  }

  public void testDoubler() {
    Iterable<Integer> doubled = new Iterable() {
      @Override
      public Iterator<Integer> iterator() {
        return newDoubler(2, 32);
      }
    };
    assertThat(doubled).containsExactly(2, 4, 8, 16, 32).inOrder();
  }

  public void testSampleCode() {
    Iterable<Integer> actual = new Iterable() {
      @Override
      public Iterator<Integer> iterator() {
        Iterator<Integer> powersOfTwo = new AbstractSequentialIterator(1) {
          protected Integer computeNext(Integer previous) {
            return (previous == 1 << 30) ? null : previous * 2;
          }
        };
        return powersOfTwo;
      }
    };
    assertThat(actual)
        .containsExactly(1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384,
            32768, 65536, 131072, 262144, 524288, 1048576, 2097152, 4194304, 8388608, 16777216,
            33554432, 67108864, 134217728, 268435456, 536870912, 1073741824)
        .inOrder();
  }

  public void testEmpty() {
    Iterator<Object> empty = newEmpty();
    assertFalse(empty.hasNext());
    try {
      empty.next();
      fail();
    } catch (NoSuchElementException expected) {
    }
    try {
      empty.remove();
      fail();
    } catch (UnsupportedOperationException expected) {
    }
  }

  public void testBroken() {
    Iterator<Object> broken = newBroken();
    assertTrue(broken.hasNext());
    // We can't retrieve even the known first element:
    try {
      broken.next();
      fail();
    } catch (MyException expected) {
    }
    try {
      broken.next();
      fail();
    } catch (MyException expected) {
    }
  }

  private static Iterator<Integer> newDoubler(int first, final int last) {
    return new AbstractSequentialIterator<Integer>(first) {
      @Override
      protected Integer computeNext(Integer previous) {
        return (previous == last) ? null : previous * 2;
      }
    };
  }

  private static <T> Iterator newEmpty() {
    return new AbstractSequentialIterator<T>(null) {
      @Override
      protected T computeNext(T previous) {
        throw new AssertionFailedError();
      }
    };
  }

  private static Iterator<Object> newBroken() {
    return new AbstractSequentialIterator<Object>("UNUSED") {
      @Override
      protected Object computeNext(Object previous) {
        throw new MyException();
      }
    };
  }

  private static class MyException extends RuntimeException {}
}

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