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 17 package com.google.common.collect; 18 19 import static com.google.common.collect.testing.IteratorFeature.UNMODIFIABLE; 20 import static com.google.common.truth.Truth.assertThat; 21 22 import com.google.common.annotations.GwtCompatible; 23 import com.google.common.annotations.GwtIncompatible; 24 import com.google.common.collect.testing.IteratorTester; 25 import java.util.Iterator; 26 import java.util.NoSuchElementException; 27 import junit.framework.AssertionFailedError; 28 import junit.framework.TestCase; 29 import org.checkerframework.checker.nullness.qual.Nullable; 30 31 /** Tests for {@link AbstractSequentialIterator}. */ 32 @GwtCompatible(emulated = true) 33 public class AbstractSequentialIteratorTest extends TestCase { 34 @GwtIncompatible // Too slow testDoublerExhaustive()35 public void testDoublerExhaustive() { 36 new IteratorTester<Integer>( 37 3, UNMODIFIABLE, ImmutableList.of(1, 2), IteratorTester.KnownOrder.KNOWN_ORDER) { 38 @Override 39 protected Iterator<Integer> newTargetIterator() { 40 return newDoubler(1, 2); 41 } 42 }.test(); 43 } 44 testDoubler()45 public void testDoubler() { 46 Iterable<Integer> doubled = 47 new Iterable<Integer>() { 48 @Override 49 public Iterator<Integer> iterator() { 50 return newDoubler(2, 32); 51 } 52 }; 53 assertThat(doubled).containsExactly(2, 4, 8, 16, 32).inOrder(); 54 } 55 testSampleCode()56 public void testSampleCode() { 57 Iterable<Integer> actual = 58 new Iterable<Integer>() { 59 @Override 60 public Iterator<Integer> iterator() { 61 Iterator<Integer> powersOfTwo = 62 new AbstractSequentialIterator<Integer>(1) { 63 @Override 64 protected @Nullable Integer computeNext(Integer previous) { 65 return (previous == 1 << 30) ? null : previous * 2; 66 } 67 }; 68 return powersOfTwo; 69 } 70 }; 71 assertThat(actual) 72 .containsExactly( 73 1, 74 2, 75 4, 76 8, 77 16, 78 32, 79 64, 80 128, 81 256, 82 512, 83 1024, 84 2048, 85 4096, 86 8192, 87 16384, 88 32768, 89 65536, 90 131072, 91 262144, 92 524288, 93 1048576, 94 2097152, 95 4194304, 96 8388608, 97 16777216, 98 33554432, 99 67108864, 100 134217728, 101 268435456, 102 536870912, 103 1073741824) 104 .inOrder(); 105 } 106 testEmpty()107 public void testEmpty() { 108 Iterator<Object> empty = newEmpty(); 109 assertFalse(empty.hasNext()); 110 try { 111 empty.next(); 112 fail(); 113 } catch (NoSuchElementException expected) { 114 } 115 try { 116 empty.remove(); 117 fail(); 118 } catch (UnsupportedOperationException expected) { 119 } 120 } 121 testBroken()122 public void testBroken() { 123 Iterator<Object> broken = newBroken(); 124 assertTrue(broken.hasNext()); 125 // We can't retrieve even the known first element: 126 try { 127 broken.next(); 128 fail(); 129 } catch (MyException expected) { 130 } 131 try { 132 broken.next(); 133 fail(); 134 } catch (MyException expected) { 135 } 136 } 137 newDoubler(int first, final int last)138 private static Iterator<Integer> newDoubler(int first, final int last) { 139 return new AbstractSequentialIterator<Integer>(first) { 140 @Override 141 protected @Nullable Integer computeNext(Integer previous) { 142 return (previous == last) ? null : previous * 2; 143 } 144 }; 145 } 146 147 private static <T> Iterator<T> newEmpty() { 148 return new AbstractSequentialIterator<T>(null) { 149 @Override 150 protected T computeNext(T previous) { 151 throw new AssertionFailedError(); 152 } 153 }; 154 } 155 156 private static Iterator<Object> newBroken() { 157 return new AbstractSequentialIterator<Object>("UNUSED") { 158 @Override 159 protected Object computeNext(Object previous) { 160 throw new MyException(); 161 } 162 }; 163 } 164 165 private static class MyException extends RuntimeException {} 166 } 167