Added unit test for base/hash.

base/hash_unittest.cc

+// 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.
+
+#include "base/hash.h"
+
+#include <string>
+#include <vector>
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+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));
+
+  // 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")));
+}
+
+}  // namespace base