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Java example source code file (HashingTest.java)

This example Java source code file (HashingTest.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

empty_string, equalstester, exception, hashcode, hashfunction, illegalargumentexception, iters, known_hashes, list, max_shards, method, nio, random, reflection, tqbfjotld, tqbfjotldp, util

The HashingTest.java Java example source code

/*
 * Copyright (C) 2011 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.hash;

import static com.google.common.base.Charsets.UTF_8;
import static java.util.Arrays.asList;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableTable;
import com.google.common.collect.Lists;
import com.google.common.collect.Table.Cell;
import com.google.common.primitives.Ints;
import com.google.common.testing.EqualsTester;
import com.google.common.testing.NullPointerTester;
import com.google.common.util.concurrent.AtomicLongMap;

import junit.framework.TestCase;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.nio.ByteBuffer;
import java.util.Collections;
import java.util.List;
import java.util.Locale;
import java.util.Random;

/**
 * Unit tests for {@link Hashing}.
 *
 * @author Dimitris Andreou
 * @author Kurt Alfred Kluever
 */
public class HashingTest extends TestCase {
  public void testMd5() {
    HashTestUtils.checkAvalanche(Hashing.md5(), 100, 0.4);
    HashTestUtils.checkNo2BitCharacteristics(Hashing.md5());
    HashTestUtils.checkNoFunnels(Hashing.md5());
    HashTestUtils.assertInvariants(Hashing.md5());
    assertEquals("Hashing.md5()", Hashing.md5().toString());
  }

  public void testSha1() {
    HashTestUtils.checkAvalanche(Hashing.sha1(), 100, 0.4);
    HashTestUtils.checkNo2BitCharacteristics(Hashing.sha1());
    HashTestUtils.checkNoFunnels(Hashing.sha1());
    HashTestUtils.assertInvariants(Hashing.sha1());
    assertEquals("Hashing.sha1()", Hashing.sha1().toString());
  }

  public void testSha256() {
    HashTestUtils.checkAvalanche(Hashing.sha256(), 100, 0.4);
    HashTestUtils.checkNo2BitCharacteristics(Hashing.sha256());
    HashTestUtils.checkNoFunnels(Hashing.sha256());
    HashTestUtils.assertInvariants(Hashing.sha256());
    assertEquals("Hashing.sha256()", Hashing.sha256().toString());
  }

  public void testSha384() {
    HashTestUtils.checkAvalanche(Hashing.sha384(), 100, 0.4);
    HashTestUtils.checkNo2BitCharacteristics(Hashing.sha384());
    HashTestUtils.checkNoFunnels(Hashing.sha384());
    HashTestUtils.assertInvariants(Hashing.sha384());
    assertEquals("Hashing.sha384()", Hashing.sha384().toString());
  }

  public void testSha512() {
    HashTestUtils.checkAvalanche(Hashing.sha512(), 100, 0.4);
    HashTestUtils.checkNo2BitCharacteristics(Hashing.sha512());
    HashTestUtils.checkNoFunnels(Hashing.sha512());
    HashTestUtils.assertInvariants(Hashing.sha512());
    assertEquals("Hashing.sha512()", Hashing.sha512().toString());
  }

  public void testCrc32() {
    HashTestUtils.assertInvariants(Hashing.crc32());
    assertEquals("Hashing.crc32()", Hashing.crc32().toString());
  }

  public void testAdler32() {
    HashTestUtils.assertInvariants(Hashing.adler32());
    assertEquals("Hashing.adler32()", Hashing.adler32().toString());
  }

  public void testMurmur3_128() {
    HashTestUtils.check2BitAvalanche(Hashing.murmur3_128(), 250, 0.20);
    HashTestUtils.checkAvalanche(Hashing.murmur3_128(), 250, 0.17);
    HashTestUtils.checkNo2BitCharacteristics(Hashing.murmur3_128());
    HashTestUtils.checkNoFunnels(Hashing.murmur3_128());
    HashTestUtils.assertInvariants(Hashing.murmur3_128());
    assertEquals("Hashing.murmur3_128(0)", Hashing.murmur3_128().toString());
  }

  public void testMurmur3_32() {
    HashTestUtils.check2BitAvalanche(Hashing.murmur3_32(), 250, 0.20);
    HashTestUtils.checkAvalanche(Hashing.murmur3_32(), 250, 0.17);
    HashTestUtils.checkNo2BitCharacteristics(Hashing.murmur3_32());
    HashTestUtils.checkNoFunnels(Hashing.murmur3_32());
    HashTestUtils.assertInvariants(Hashing.murmur3_32());
    assertEquals("Hashing.murmur3_32(0)", Hashing.murmur3_32().toString());
  }

  public void testSipHash24() {
    HashTestUtils.check2BitAvalanche(Hashing.sipHash24(), 250, 0.14);
    HashTestUtils.checkAvalanche(Hashing.sipHash24(), 250, 0.10);
    HashTestUtils.checkNo2BitCharacteristics(Hashing.sipHash24());
    HashTestUtils.checkNoFunnels(Hashing.sipHash24());
    HashTestUtils.assertInvariants(Hashing.sipHash24());
    assertEquals("Hashing.sipHash24(506097522914230528, 1084818905618843912)",
        Hashing.sipHash24().toString());
  }

  @AndroidIncompatible // slow TODO(cpovirk): Maybe just reduce iterations under Android.
  public void testGoodFastHash() {
    for (int i = 1; i < 200; i += 17) {
      HashFunction hasher = Hashing.goodFastHash(i);
      assertTrue(hasher.bits() >= i);
      HashTestUtils.assertInvariants(hasher);
    }
  }

  // goodFastHash(32) uses Murmur3_32. Use the same epsilon bounds.
  public void testGoodFastHash32() {
    HashTestUtils.check2BitAvalanche(Hashing.goodFastHash(32), 250, 0.20);
    HashTestUtils.checkAvalanche(Hashing.goodFastHash(32), 250, 0.17);
    HashTestUtils.checkNo2BitCharacteristics(Hashing.goodFastHash(32));
    HashTestUtils.checkNoFunnels(Hashing.goodFastHash(32));
    HashTestUtils.assertInvariants(Hashing.goodFastHash(32));
  }

  // goodFastHash(128) uses Murmur3_128. Use the same epsilon bounds.
  public void testGoodFastHash128() {
    HashTestUtils.check2BitAvalanche(Hashing.goodFastHash(128), 250, 0.20);
    HashTestUtils.checkAvalanche(Hashing.goodFastHash(128), 250, 0.17);
    HashTestUtils.checkNo2BitCharacteristics(Hashing.goodFastHash(128));
    HashTestUtils.checkNoFunnels(Hashing.goodFastHash(128));
    HashTestUtils.assertInvariants(Hashing.goodFastHash(128));
  }

  // goodFastHash(256) uses Murmur3_128. Use the same epsilon bounds.
  public void testGoodFastHash256() {
    HashTestUtils.check2BitAvalanche(Hashing.goodFastHash(256), 250, 0.20);
    HashTestUtils.checkAvalanche(Hashing.goodFastHash(256), 250, 0.17);
    HashTestUtils.checkNo2BitCharacteristics(Hashing.goodFastHash(256));
    HashTestUtils.checkNoFunnels(Hashing.goodFastHash(256));
    HashTestUtils.assertInvariants(Hashing.goodFastHash(256));
  }

  public void testConsistentHash_correctness() {
    long[] interestingValues = { -1, 0, 1, 2, Long.MAX_VALUE, Long.MIN_VALUE };
    for (long h : interestingValues) {
      checkConsistentHashCorrectness(h);
    }
    Random r = new Random(7);
    for (int i = 0; i < 20; i++) {
      checkConsistentHashCorrectness(r.nextLong());
    }
  }

  private void checkConsistentHashCorrectness(long hashCode) {
    int last = 0;
    for (int shards = 1; shards <= 100000; shards++) {
      int b = Hashing.consistentHash(hashCode, shards);
      if (b != last) {
        assertEquals(shards - 1, b);
        last = b;
      }
    }
  }

  public void testConsistentHash_probabilities() {
    AtomicLongMap<Integer> map = AtomicLongMap.create();
    Random r = new Random(9);
    for (int i = 0; i < ITERS; i++) {
      countRemaps(r.nextLong(), map);
    }
    for (int shard = 2; shard <= MAX_SHARDS; shard++) {
      // Rough: don't exceed 1.2x the expected number of remaps by more than 20
      assertTrue(map.get(shard) <= 1.2 * ITERS / shard + 20);
    }
  }

  private void countRemaps(long h, AtomicLongMap<Integer> map) {
    int last = 0;
    for (int shards = 2; shards <= MAX_SHARDS; shards++) {
      int chosen = Hashing.consistentHash(h, shards);
      if (chosen != last) {
        map.incrementAndGet(shards);
        last = chosen;
      }
    }
  }

  private static final int ITERS = 10000;
  private static final int MAX_SHARDS = 500;

  public void testConsistentHash_outOfRange() {
    try {
      Hashing.consistentHash(5L, 0);
      fail();
    } catch (IllegalArgumentException expected) {
    }
  }

  public void testConsistentHash_ofHashCode() {
    checkSameResult(HashCode.fromLong(1), 1);
    checkSameResult(HashCode.fromLong(0x9999999999999999L), 0x9999999999999999L);
    checkSameResult(HashCode.fromInt(0x99999999), 0x0000000099999999L);
  }

  public void checkSameResult(HashCode hashCode, long equivLong) {
    assertEquals(Hashing.consistentHash(equivLong, 5555), Hashing.consistentHash(hashCode, 5555));
  }

  /**
   * Check a few "golden" values to see that implementations across languages
   * are equivalent.
   */
  public void testConsistentHash_linearCongruentialGeneratorCompatibility() {
    int[] golden100 =
        { 0, 55, 62, 8, 45, 59, 86, 97, 82, 59,
          73, 37, 17, 56, 86, 21, 90, 37, 38, 83 };
    for (int i = 0; i < golden100.length; i++) {
      assertEquals(golden100[i], Hashing.consistentHash(i, 100));
    }
    assertEquals(6, Hashing.consistentHash(10863919174838991L, 11));
    assertEquals(3, Hashing.consistentHash(2016238256797177309L, 11));
    assertEquals(5, Hashing.consistentHash(1673758223894951030L, 11));
    assertEquals(80343, Hashing.consistentHash(2, 100001));
    assertEquals(22152, Hashing.consistentHash(2201, 100001));
    assertEquals(15018, Hashing.consistentHash(2202, 100001));
  }

  private static final double MAX_PERCENT_SPREAD = 0.5;
  private static final long RANDOM_SEED = 177L;

  public void testCombineOrdered_empty() {
    try {
      Hashing.combineOrdered(Collections.<HashCode>emptySet());
      fail();
    } catch (IllegalArgumentException expected) {
    }
  }

  public void testCombineOrdered_differentBitLengths() {
    try {
      HashCode unused =
          Hashing.combineOrdered(ImmutableList.of(HashCode.fromInt(32), HashCode.fromLong(32L)));
      fail();
    } catch (IllegalArgumentException expected) {
    }
  }

  public void testCombineOrdered() {
    HashCode hash31 = HashCode.fromInt(31);
    HashCode hash32 = HashCode.fromInt(32);
    assertEquals(hash32, Hashing.combineOrdered(ImmutableList.of(hash32)));
    assertEquals(HashCode.fromBytes(new byte[] { (byte) 0x80, 0, 0, 0 }),
        Hashing.combineOrdered(ImmutableList.of(hash32, hash32)));
    assertEquals(HashCode.fromBytes(new byte[] { (byte) 0xa0, 0, 0, 0 }),
        Hashing.combineOrdered(ImmutableList.of(hash32, hash32, hash32)));
    assertFalse(
        Hashing.combineOrdered(ImmutableList.of(hash31, hash32)).equals(
        Hashing.combineOrdered(ImmutableList.of(hash32, hash31))));
  }

  public void testCombineOrdered_randomHashCodes() {
    Random random = new Random(7);
    List<HashCode> hashCodes = Lists.newArrayList();
    for (int i = 0; i < 10; i++) {
      hashCodes.add(HashCode.fromLong(random.nextLong()));
    }
    HashCode hashCode1 = Hashing.combineOrdered(hashCodes);
    Collections.shuffle(hashCodes, random);
    HashCode hashCode2 = Hashing.combineOrdered(hashCodes);

    assertFalse(hashCode1.equals(hashCode2));
  }

  public void testCombineUnordered_empty() {
    try {
      Hashing.combineUnordered(Collections.<HashCode>emptySet());
      fail();
    } catch (IllegalArgumentException expected) {
    }
  }

  public void testCombineUnordered_differentBitLengths() {
    try {
      HashCode unused =
          Hashing.combineUnordered(ImmutableList.of(HashCode.fromInt(32), HashCode.fromLong(32L)));
      fail();
    } catch (IllegalArgumentException expected) {
    }
  }

  public void testCombineUnordered() {
    HashCode hash31 = HashCode.fromInt(31);
    HashCode hash32 = HashCode.fromInt(32);
    assertEquals(hash32, Hashing.combineUnordered(ImmutableList.of(hash32)));
    assertEquals(HashCode.fromInt(64), Hashing.combineUnordered(ImmutableList.of(hash32, hash32)));
    assertEquals(HashCode.fromInt(96),
        Hashing.combineUnordered(ImmutableList.of(hash32, hash32, hash32)));
    assertEquals(
        Hashing.combineUnordered(ImmutableList.of(hash31, hash32)),
        Hashing.combineUnordered(ImmutableList.of(hash32, hash31)));
  }

  public void testCombineUnordered_randomHashCodes() {
    Random random = new Random(RANDOM_SEED);
    List<HashCode> hashCodes = Lists.newArrayList();
    for (int i = 0; i < 10; i++) {
      hashCodes.add(HashCode.fromLong(random.nextLong()));
    }
    HashCode hashCode1 = Hashing.combineUnordered(hashCodes);
    Collections.shuffle(hashCodes);
    HashCode hashCode2 = Hashing.combineUnordered(hashCodes);

    assertEquals(hashCode1, hashCode2);
  }

  // This isn't specified by contract, but it'll still be nice to know if this behavior changes.
  public void testConcatenating_equals() {
    new EqualsTester()
        .addEqualityGroup(Hashing.concatenating(asList(Hashing.md5())))
        .addEqualityGroup(Hashing.concatenating(asList(Hashing.murmur3_32())))
        .addEqualityGroup(
            Hashing.concatenating(Hashing.md5(), Hashing.md5()),
            Hashing.concatenating(asList(Hashing.md5(), Hashing.md5())))
        .addEqualityGroup(
            Hashing.concatenating(Hashing.murmur3_32(), Hashing.md5()),
            Hashing.concatenating(asList(Hashing.murmur3_32(), Hashing.md5())))
        .addEqualityGroup(
            Hashing.concatenating(Hashing.md5(), Hashing.murmur3_32()),
            Hashing.concatenating(asList(Hashing.md5(), Hashing.murmur3_32())))
        .testEquals();
  }

  public void testConcatenatingIterable_bits() {
    assertEquals(
        Hashing.md5().bits() + Hashing.md5().bits(),
        Hashing.concatenating(asList(Hashing.md5(), Hashing.md5())).bits());
    assertEquals(
        Hashing.md5().bits() + Hashing.murmur3_32().bits(),
        Hashing.concatenating(asList(Hashing.md5(), Hashing.murmur3_32())).bits());
    assertEquals(
        Hashing.md5().bits() + Hashing.murmur3_32().bits() + Hashing.murmur3_128().bits(),
        Hashing.concatenating(
            asList(Hashing.md5(), Hashing.murmur3_32(), Hashing.murmur3_128())).bits());
  }

  public void testConcatenatingVarArgs_bits() {
    assertEquals(
        Hashing.md5().bits() + Hashing.md5().bits(),
        Hashing.concatenating(Hashing.md5(), Hashing.md5()).bits());
    assertEquals(
        Hashing.md5().bits() + Hashing.murmur3_32().bits(),
        Hashing.concatenating(Hashing.md5(), Hashing.murmur3_32()).bits());
    assertEquals(
        Hashing.md5().bits() + Hashing.murmur3_32().bits() + Hashing.murmur3_128().bits(),
        Hashing.concatenating(Hashing.md5(), Hashing.murmur3_32(), Hashing.murmur3_128()).bits());
  }

  public void testConcatenatingHashFunction_makeHash() {
    byte[] md5Hash = Hashing.md5().hashLong(42L).asBytes();
    byte[] murmur3Hash = Hashing.murmur3_32().hashLong(42L).asBytes();
    byte[] combined = new byte[md5Hash.length + murmur3Hash.length];
    ByteBuffer buffer = ByteBuffer.wrap(combined);
    buffer.put(md5Hash);
    buffer.put(murmur3Hash);
    HashCode expected = HashCode.fromBytes(combined);

    assertEquals(expected,
        Hashing.concatenating(Hashing.md5(), Hashing.murmur3_32()).hashLong(42L));
    assertEquals(expected,
        Hashing.concatenating(asList(Hashing.md5(), Hashing.murmur3_32())).hashLong(42L));
  }

  public void testHashIntReverseBytesVsHashBytesIntsToByteArray() {
    int input = 42;
    assertEquals(
        Hashing.md5().hashBytes(Ints.toByteArray(input)),
        Hashing.md5().hashInt(Integer.reverseBytes(input)));
  }

  public void testHashIntVsForLoop() {
    int input = 42;
    HashCode expected = Hashing.md5().hashInt(input);

    Hasher hasher = Hashing.md5().newHasher();
    for (int i = 0; i < 32; i += 8) {
      hasher.putByte((byte) (input >> i));
    }
    HashCode actual = hasher.hash();

    assertEquals(expected, actual);
  }

  private static final String EMPTY_STRING = "";
  private static final String TQBFJOTLD = "The quick brown fox jumps over the lazy dog";
  private static final String TQBFJOTLDP = "The quick brown fox jumps over the lazy dog.";

  private static final ImmutableTable<HashFunction, String, String> KNOWN_HASHES =
      ImmutableTable.<HashFunction, String, String>builder()
          .put(Hashing.adler32(), EMPTY_STRING, "01000000")
          .put(Hashing.adler32(), TQBFJOTLD, "da0fdc5b")
          .put(Hashing.adler32(), TQBFJOTLDP, "0810e46b")
          .put(Hashing.md5(), EMPTY_STRING, "d41d8cd98f00b204e9800998ecf8427e")
          .put(Hashing.md5(), TQBFJOTLD, "9e107d9d372bb6826bd81d3542a419d6")
          .put(Hashing.md5(), TQBFJOTLDP, "e4d909c290d0fb1ca068ffaddf22cbd0")
          .put(Hashing.murmur3_128(), EMPTY_STRING, "00000000000000000000000000000000")
          .put(Hashing.murmur3_128(), TQBFJOTLD, "6c1b07bc7bbc4be347939ac4a93c437a")
          .put(Hashing.murmur3_128(), TQBFJOTLDP, "c902e99e1f4899cde7b68789a3a15d69")
          .put(Hashing.murmur3_32(), EMPTY_STRING, "00000000")
          .put(Hashing.murmur3_32(), TQBFJOTLD, "23f74f2e")
          .put(Hashing.murmur3_32(), TQBFJOTLDP, "fc8bc4d5")
          .put(Hashing.sha1(), EMPTY_STRING, "da39a3ee5e6b4b0d3255bfef95601890afd80709")
          .put(Hashing.sha1(), TQBFJOTLD, "2fd4e1c67a2d28fced849ee1bb76e7391b93eb12")
          .put(Hashing.sha1(), TQBFJOTLDP, "408d94384216f890ff7a0c3528e8bed1e0b01621")
          .put(
              Hashing.sha256(),
              EMPTY_STRING,
              "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855")
          .put(
              Hashing.sha256(),
              TQBFJOTLD,
              "d7a8fbb307d7809469ca9abcb0082e4f8d5651e46d3cdb762d02d0bf37c9e592")
          .put(
              Hashing.sha256(),
              TQBFJOTLDP,
              "ef537f25c895bfa782526529a9b63d97aa631564d5d789c2b765448c8635fb6c")
          .put(
              Hashing.sha384(),
              EMPTY_STRING,
              "38b060a751ac96384cd9327eb1b1e36a21fdb71114be07434c0cc7bf63f6e1da2"
                  + "74edebfe76f65fbd51ad2f14898b95b")
          .put(
              Hashing.sha384(),
              TQBFJOTLD,
              "ca737f1014a48f4c0b6dd43cb177b0afd9e5169367544c494011e3317dbf9a509"
                  + "cb1e5dc1e85a941bbee3d7f2afbc9b1")
          .put(
              Hashing.sha384(),
              TQBFJOTLDP,
              "ed892481d8272ca6df370bf706e4d7bc1b5739fa2177aae6c50e946678718fc67"
                  + "a7af2819a021c2fc34e91bdb63409d7")
          .put(
              Hashing.sha512(),
              EMPTY_STRING,
              "cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce"
                  + "47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e")
          .put(
              Hashing.sha512(),
              TQBFJOTLD,
              "07e547d9586f6a73f73fbac0435ed76951218fb7d0c8d788a309d785436bbb64"
                  + "2e93a252a954f23912547d1e8a3b5ed6e1bfd7097821233fa0538f3db854fee6")
          .put(
              Hashing.sha512(),
              TQBFJOTLDP,
              "91ea1245f20d46ae9a037a989f54f1f790f0a47607eeb8a14d12890cea77a1bb"
                  + "c6c7ed9cf205e67b7f2b8fd4c7dfd3a7a8617e45f3c463d481c7e586c39ac1ed")
          .put(Hashing.crc32(), EMPTY_STRING, "00000000")
          .put(Hashing.crc32(), TQBFJOTLD, "39a34f41")
          .put(Hashing.crc32(), TQBFJOTLDP, "e9259051")
          .put(Hashing.sipHash24(), EMPTY_STRING, "310e0edd47db6f72")
          .put(Hashing.sipHash24(), TQBFJOTLD, "e46f1fdc05612752")
          .put(Hashing.sipHash24(), TQBFJOTLDP, "9b602581fce4d4f8")
          .put(Hashing.crc32c(), EMPTY_STRING, "00000000")
          .put(Hashing.crc32c(), TQBFJOTLD, "04046222")
          .put(Hashing.crc32c(), TQBFJOTLDP, "b3970019")
          .put(Hashing.farmHashFingerprint64(), EMPTY_STRING, "4f40902f3b6ae19a")
          .put(Hashing.farmHashFingerprint64(), TQBFJOTLD, "34511b3bf383beab")
          .put(Hashing.farmHashFingerprint64(), TQBFJOTLDP, "737d7e5f8660653e")
          .build();

  public void testAllHashFunctionsHaveKnownHashes() throws Exception {
    for (Method method : Hashing.class.getDeclaredMethods()) {
      if (method.getReturnType().equals(HashFunction.class) // must return HashFunction
          && Modifier.isPublic(method.getModifiers()) // only the public methods
          && method.getParameterTypes().length == 0) { // only the seed-less grapes^W hash functions
        HashFunction hashFunction = (HashFunction) method.invoke(Hashing.class);
        assertTrue("There should be at least 3 entries in KNOWN_HASHES for " + hashFunction,
            KNOWN_HASHES.row(hashFunction).size() >= 3);
      }
    }
  }

  public void testKnownUtf8Hashing() {
    for (Cell<HashFunction, String, String> cell : KNOWN_HASHES.cellSet()) {
      HashFunction func = cell.getRowKey();
      String input = cell.getColumnKey();
      String expected = cell.getValue();
      assertEquals(
          String.format(Locale.ROOT, "Known hash for hash(%s, UTF_8) failed", input),
          expected,
          func.hashString(input, UTF_8).toString());
    }
  }

  public void testNullPointers() {
    NullPointerTester tester = new NullPointerTester()
        .setDefault(byte[].class, "secret key".getBytes(UTF_8))
        .setDefault(HashCode.class, HashCode.fromLong(0));
    tester.testAllPublicStaticMethods(Hashing.class);
  }

  public void testSeedlessHashFunctionEquals() throws Exception {
    assertSeedlessHashFunctionEquals(Hashing.class);
  }

  public void testSeededHashFunctionEquals() throws Exception {
    assertSeededHashFunctionEquals(Hashing.class);
  }

  /**
   * Tests equality of {@link Hashing#goodFastHash} instances. This test must be separate from
   * {@link #testSeededHashFunctionEquals} because the parameter to {@code goodFastHash} is a size,
   * not a seed, and because that size is rounded up. Thus, {@code goodFastHash} instances with
   * different parameters can be equal. That fact is a problem for {@code
   * testSeededHashFunctionEquals}.
   */
  public void testGoodFastHashEquals() throws Exception {
    HashFunction hashFunction1a = Hashing.goodFastHash(1);
    HashFunction hashFunction1b = Hashing.goodFastHash(32);
    HashFunction hashFunction2a = Hashing.goodFastHash(33);
    HashFunction hashFunction2b = Hashing.goodFastHash(128);
    HashFunction hashFunction3a = Hashing.goodFastHash(129);
    HashFunction hashFunction3b = Hashing.goodFastHash(256);
    HashFunction hashFunction4a = Hashing.goodFastHash(257);
    HashFunction hashFunction4b = Hashing.goodFastHash(384);

    new EqualsTester()
        .addEqualityGroup(hashFunction1a, hashFunction1b)
        .addEqualityGroup(hashFunction2a, hashFunction2b)
        .addEqualityGroup(hashFunction3a, hashFunction3b)
        .addEqualityGroup(hashFunction4a, hashFunction4b)
        .testEquals();

    assertEquals(hashFunction1a.toString(), hashFunction1b.toString());
    assertEquals(hashFunction2a.toString(), hashFunction2b.toString());
    assertEquals(hashFunction3a.toString(), hashFunction3b.toString());
    assertEquals(hashFunction4a.toString(), hashFunction4b.toString());
  }

  static void assertSeedlessHashFunctionEquals(Class<?> clazz) throws Exception {
    for (Method method : clazz.getDeclaredMethods()) {
      if (method.getReturnType().equals(HashFunction.class) // must return HashFunction
          && Modifier.isPublic(method.getModifiers()) // only the public methods
          && method.getParameterTypes().length == 0) { // only the seed-less hash functions
        HashFunction hashFunction1a = (HashFunction) method.invoke(clazz);
        HashFunction hashFunction1b = (HashFunction) method.invoke(clazz);

        new EqualsTester()
            .addEqualityGroup(hashFunction1a, hashFunction1b)
            .testEquals();

        // Make sure we're returning not only equal instances, but constants.
        assertSame(hashFunction1a, hashFunction1b);

        assertEquals(hashFunction1a.toString(), hashFunction1b.toString());
      }
    }
  }

  static void assertSeededHashFunctionEquals(Class<?> clazz) throws Exception {
    Random random = new Random(RANDOM_SEED);
    for (Method method : clazz.getDeclaredMethods()) {
      if (method.getReturnType().equals(HashFunction.class) // must return HashFunction
          && Modifier.isPublic(method.getModifiers()) // only the public methods
          && method.getParameterTypes().length != 0 // only the seeded hash functions
          && !method.getName().equals("concatenating") // don't test Hashing.concatenating()
          && !method.getName().equals("goodFastHash") // tested in testGoodFastHashEquals
          && !method.getName().startsWith("hmac")) { // skip hmac functions
        Object[] params1 = new Object[method.getParameterTypes().length];
        Object[] params2 = new Object[method.getParameterTypes().length];
        for (int i = 0; i < params1.length; i++) {
          if (method.getParameterTypes()[i] == int.class) {
            params1[i] = random.nextInt();
            params2[i] = random.nextInt();
          } else if (method.getParameterTypes()[i] == long.class) {
            params1[i] = random.nextLong();
            params2[i] = random.nextLong();
          } else {
            fail("Unable to create a random parameter for " + method.getParameterTypes()[i]);
          }
        }
        HashFunction hashFunction1a = (HashFunction) method.invoke(clazz, params1);
        HashFunction hashFunction1b = (HashFunction) method.invoke(clazz, params1);
        HashFunction hashFunction2 = (HashFunction) method.invoke(clazz, params2);

        new EqualsTester()
            .addEqualityGroup(hashFunction1a, hashFunction1b)
            .addEqualityGroup(hashFunction2)
            .testEquals();

        assertEquals(hashFunction1a.toString(), hashFunction1b.toString());
      }
    }
  }
}

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