1 /* 2 * Copyright (C) 2011 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.hash; 18 19 import com.google.common.collect.ImmutableList; 20 import com.google.common.hash.HashTestUtils.RandomHasherAction; 21 22 import junit.framework.TestCase; 23 24 import java.io.ByteArrayOutputStream; 25 import java.nio.ByteBuffer; 26 import java.nio.charset.Charset; 27 import java.util.Arrays; 28 import java.util.List; 29 import java.util.Random; 30 31 /** 32 * Tests for AbstractNonStreamingHashFunction. 33 */ 34 public class AbstractNonStreamingHashFunctionTest extends TestCase { 35 /** 36 * Constructs two trivial HashFunctions (output := input), one streaming and one non-streaming, 37 * and checks that their results are identical, no matter which newHasher version we used. 38 */ testExhaustive()39 public void testExhaustive() { 40 List<Hasher> hashers = ImmutableList.of( 41 new StreamingVersion().newHasher(), 42 new StreamingVersion().newHasher(52), 43 new NonStreamingVersion().newHasher(), 44 new NonStreamingVersion().newHasher(123)); 45 Random random = new Random(0); 46 for (int i = 0; i < 200; i++) { 47 RandomHasherAction.pickAtRandom(random).performAction(random, hashers); 48 } 49 HashCode[] codes = new HashCode[hashers.size()]; 50 for (int i = 0; i < hashers.size(); i++) { 51 codes[i] = hashers.get(i).hash(); 52 } 53 for (int i = 1; i < codes.length; i++) { 54 assertEquals(codes[i - 1], codes[i]); 55 } 56 } 57 testPutStringWithLowSurrogate()58 public void testPutStringWithLowSurrogate() { 59 // we pad because the dummy hash function we use to test this, merely copies the input into 60 // the output, so the input must be at least 32 bits, since the output has to be that long 61 assertPutString(new char[] { 'p', HashTestUtils.randomLowSurrogate(new Random()) }); 62 } 63 testPutStringWithHighSurrogate()64 public void testPutStringWithHighSurrogate() { 65 // we pad because the dummy hash function we use to test this, merely copies the input into 66 // the output, so the input must be at least 32 bits, since the output has to be that long 67 assertPutString(new char[] { 'p', HashTestUtils.randomHighSurrogate(new Random()) }); 68 } 69 testPutStringWithLowHighSurrogate()70 public void testPutStringWithLowHighSurrogate() { 71 assertPutString(new char[] { 72 HashTestUtils.randomLowSurrogate(new Random()), 73 HashTestUtils.randomHighSurrogate(new Random()) }); 74 } 75 testPutStringWithHighLowSurrogate()76 public void testPutStringWithHighLowSurrogate() { 77 assertPutString(new char[] { 78 HashTestUtils.randomHighSurrogate(new Random()), 79 HashTestUtils.randomLowSurrogate(new Random()) }); 80 } 81 assertPutString(char[] chars)82 private static void assertPutString(char[] chars) { 83 Hasher h1 = new NonStreamingVersion().newHasher(); 84 Hasher h2 = new NonStreamingVersion().newHasher(); 85 String s = new String(chars); 86 // this is the correct implementation of the spec 87 for (int i = 0; i < s.length(); i++) { 88 h1.putChar(s.charAt(i)); 89 } 90 h2.putUnencodedChars(s); 91 assertEquals(h1.hash(), h2.hash()); 92 } 93 94 static class StreamingVersion extends AbstractStreamingHashFunction { 95 @Override bits()96 public int bits() { 97 return 32; 98 } 99 100 @Override newHasher()101 public Hasher newHasher() { 102 return new AbstractStreamingHasher(4, 4) { 103 final ByteArrayOutputStream out = new ByteArrayOutputStream(); 104 @Override 105 HashCode makeHash() { 106 return HashCode.fromBytes(out.toByteArray()); 107 } 108 109 @Override 110 protected void process(ByteBuffer bb) { 111 while (bb.hasRemaining()) { 112 out.write(bb.get()); 113 } 114 } 115 116 @Override 117 protected void processRemaining(ByteBuffer bb) { 118 while (bb.hasRemaining()) { 119 out.write(bb.get()); 120 } 121 } 122 }; 123 } 124 } 125 126 static class NonStreamingVersion extends AbstractNonStreamingHashFunction { 127 @Override bits()128 public int bits() { 129 return 32; 130 } 131 132 @Override hashBytes(byte[] input)133 public HashCode hashBytes(byte[] input) { 134 return HashCode.fromBytes(input); 135 } 136 137 @Override hashBytes(byte[] input, int off, int len)138 public HashCode hashBytes(byte[] input, int off, int len) { 139 return HashCode.fromBytes(Arrays.copyOfRange(input, off, off + len)); 140 } 141 142 @Override hashString(CharSequence input, Charset charset)143 public HashCode hashString(CharSequence input, Charset charset) { 144 throw new UnsupportedOperationException(); 145 } 146 147 @Override hashLong(long input)148 public HashCode hashLong(long input) { 149 throw new UnsupportedOperationException(); 150 } 151 152 @Override hashInt(int input)153 public HashCode hashInt(int input) { 154 throw new UnsupportedOperationException(); 155 } 156 } 157 } 158