1/*
2 * Copyright (C) 2010 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.common.collect;
18
19import static com.google.common.collect.testing.IteratorFeature.UNMODIFIABLE;
20import static org.junit.contrib.truth.Truth.ASSERT;
21
22import com.google.common.annotations.GwtCompatible;
23import com.google.common.annotations.GwtIncompatible;
24import com.google.common.collect.testing.IteratorTester;
25
26import junit.framework.AssertionFailedError;
27import junit.framework.TestCase;
28
29import java.util.Iterator;
30import java.util.NoSuchElementException;
31
32/** Tests for {@link AbstractLinkedIterator}. */
33@GwtCompatible(emulated = true)
34public class AbstractLinkedIteratorTest extends TestCase {
35  @GwtIncompatible("Too slow")
36  public void testDoublerExhaustive() {
37    new IteratorTester<Integer>(3, UNMODIFIABLE, ImmutableList.of(1, 2),
38        IteratorTester.KnownOrder.KNOWN_ORDER) {
39      @Override
40      protected Iterator<Integer> newTargetIterator() {
41        return newDoubler(1, 2);
42      }
43    }.test();
44  }
45
46  public void testDoubler() {
47    Iterable<Integer> doubled = new Iterable<Integer>() {
48      @Override
49      public Iterator<Integer> iterator() {
50        return newDoubler(2, 32);
51      }
52    };
53    ASSERT.that(doubled).hasContentsInOrder(2, 4, 8, 16, 32);
54  }
55
56  public void testSampleCode() {
57    Iterable<Integer> actual = new Iterable<Integer>() {
58      @Override
59      public Iterator<Integer> iterator() {
60        Iterator<Integer> powersOfTwo = new AbstractLinkedIterator<Integer>(1) {
61          protected Integer computeNext(Integer previous) {
62            return (previous == 1 << 30) ? null : previous * 2;
63          }
64        };
65        return powersOfTwo;
66      }
67    };
68    ASSERT.that(actual).hasContentsInOrder(1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096,
69        8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576, 2097152, 4194304, 8388608,
70        16777216, 33554432, 67108864, 134217728, 268435456, 536870912, 1073741824);
71  }
72
73  public void testEmpty() {
74    Iterator<Object> empty = newEmpty();
75    assertFalse(empty.hasNext());
76    try {
77      empty.next();
78      fail();
79    } catch (NoSuchElementException expected) {
80    }
81    try {
82      empty.remove();
83      fail();
84    } catch (UnsupportedOperationException expected) {
85    }
86  }
87
88  public void testBroken() {
89    Iterator<Object> broken = newBroken();
90    assertTrue(broken.hasNext());
91    // We can't retrieve even the known first element:
92    try {
93      broken.next();
94      fail();
95    } catch (MyException expected) {
96    }
97    try {
98      broken.next();
99      fail();
100    } catch (MyException expected) {
101    }
102  }
103
104  private static Iterator<Integer> newDoubler(int first, final int last) {
105    return new AbstractLinkedIterator<Integer>(first) {
106      @Override
107      protected Integer computeNext(Integer previous) {
108        return (previous == last) ? null : previous * 2;
109      }
110    };
111  }
112
113  private static <T> Iterator<T> newEmpty() {
114    return new AbstractLinkedIterator<T>(null) {
115      @Override
116      protected T computeNext(T previous) {
117        throw new AssertionFailedError();
118      }
119    };
120  }
121
122  private static Iterator<Object> newBroken() {
123    return new AbstractLinkedIterator<Object>("UNUSED") {
124      @Override
125      protected Object computeNext(Object previous) {
126        throw new MyException();
127      }
128    };
129  }
130
131  private static class MyException extends RuntimeException {}
132}
133