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