hash_unittest.cc 2.25 KB
Newer Older
gejun's avatar
gejun committed
1 2 3 4
// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

5
#include "butil/hash.h"
gejun's avatar
gejun committed
6 7 8 9 10 11

#include <string>
#include <vector>

#include <gtest/gtest.h>

12
namespace butil {
gejun's avatar
gejun committed
13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81

TEST(HashTest, String) {
  std::string str;
  // Empty string (should hash to 0).
  str = "";
  EXPECT_EQ(0u, Hash(str));

  // Simple test.
  str = "hello world";
  EXPECT_EQ(2794219650u, Hash(str));

  // Change one bit.
  str = "helmo world";
  EXPECT_EQ(1006697176u, Hash(str));

  // Insert a null byte.
  str = "hello  world";
  str[5] = '\0';
  EXPECT_EQ(2319902537u, Hash(str));

  // Test that the bytes after the null contribute to the hash.
  str = "hello  worle";
  str[5] = '\0';
  EXPECT_EQ(553904462u, Hash(str));

  // Extremely long string.
  // Also tests strings with high bit set, and null byte.
  std::vector<char> long_string_buffer;
  for (int i = 0; i < 4096; ++i)
    long_string_buffer.push_back((i % 256) - 128);
  str.assign(&long_string_buffer.front(), long_string_buffer.size());
  EXPECT_EQ(2797962408u, Hash(str));

  // All possible lengths (mod 4). Tests separate code paths. Also test with
  // final byte high bit set (regression test for http://crbug.com/90659).
  // Note that the 1 and 3 cases have a weird bug where the final byte is
  // treated as a signed char. It was decided on the above bug discussion to
  // enshrine that behaviour as "correct" to avoid invalidating existing hashes.

  // Length mod 4 == 0.
  str = "hello w\xab";
  EXPECT_EQ(615571198u, Hash(str));
  // Length mod 4 == 1.
  str = "hello wo\xab";
  EXPECT_EQ(623474296u, Hash(str));
  // Length mod 4 == 2.
  str = "hello wor\xab";
  EXPECT_EQ(4278562408u, Hash(str));
  // Length mod 4 == 3.
  str = "hello worl\xab";
  EXPECT_EQ(3224633008u, Hash(str));
}

TEST(HashTest, CString) {
  const char* str;
  // Empty string (should hash to 0).
  str = "";
  EXPECT_EQ(0u, Hash(str, strlen(str)));

  // Simple test.
  str = "hello world";
  EXPECT_EQ(2794219650u, Hash(str, strlen(str)));

  // Ensure that it stops reading after the given length, and does not expect a
  // null byte.
  str = "hello world; don't read this part";
  EXPECT_EQ(2794219650u, Hash(str, strlen("hello world")));
}

82
}  // namespace butil