base/hash_unittest.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/hash.h"
   6
   7 #include <string>
   8 #include <vector>
   9
  10 #include "testing/gtest/include/gtest/gtest.h"
  11
  12 namespace base {
  13
  14 TEST(HashTest, String) {
  15   std::string str;
  16   // Empty string (should hash to 0).
  17   str = "";
  18   EXPECT_EQ(0u, Hash(str));
  19
  20   // Simple test.
  21   str = "hello world";
  22   EXPECT_EQ(2794219650u, Hash(str));
  23
  24   // Change one bit.
  25   str = "helmo world";
  26   EXPECT_EQ(1006697176u, Hash(str));
  27
  28   // Insert a null byte.
  29   str = "hello  world";
  30   str[5] = '\0';
  31   EXPECT_EQ(2319902537u, Hash(str));
  32
  33   // Test that the bytes after the null contribute to the hash.
  34   str = "hello  worle";
  35   str[5] = '\0';
  36   EXPECT_EQ(553904462u, Hash(str));
  37
  38   // Extremely long string.
  39   // Also tests strings with high bit set, and null byte.
  40   std::vector<char> long_string_buffer;
  41   for (int i = 0; i < 4096; ++i)
  42     long_string_buffer.push_back((i % 256) - 128);
  43   str.assign(&long_string_buffer.front(), long_string_buffer.size());
  44   EXPECT_EQ(2797962408u, Hash(str));
  45
  46   // All possible lengths (mod 4). Tests separate code paths. Also test with
  47   // final byte high bit set (regression test for http://crbug.com/90659).
  48   // Note that the 1 and 3 cases have a weird bug where the final byte is
  49   // treated as a signed char. It was decided on the above bug discussion to
  50   // enshrine that behaviour as "correct" to avoid invalidating existing hashes.
  51
  52   // Length mod 4 == 0.
  53   str = "hello w\xab";
  54   EXPECT_EQ(615571198u, Hash(str));
  55   // Length mod 4 == 1.
  56   str = "hello wo\xab";
  57   EXPECT_EQ(623474296u, Hash(str));
  58   // Length mod 4 == 2.
  59   str = "hello wor\xab";
  60   EXPECT_EQ(4278562408u, Hash(str));
  61   // Length mod 4 == 3.
  62   str = "hello worl\xab";
  63   EXPECT_EQ(3224633008u, Hash(str));
  64 }
  65
  66 TEST(HashTest, CString) {
  67   const char* str;
  68   // Empty string (should hash to 0).
  69   str = "";
  70   EXPECT_EQ(0u, Hash(str, strlen(str)));
  71
  72   // Simple test.
  73   str = "hello world";
  74   EXPECT_EQ(2794219650u, Hash(str, strlen(str)));
  75
  76   // Ensure that it stops reading after the given length, and does not expect a
  77   // null byte.
  78   str = "hello world; don't read this part";
  79   EXPECT_EQ(2794219650u, Hash(str, strlen("hello world")));
  80 }
  81
  82 }  // namespace base