cube_root_test.cc revision c2e0dbddbe15c98d52c4786dac06cb8952a8ae6d 
1// Copyright (c) 2013 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/basictypes.h"
6#include "net/quic/congestion_control/cube_root.h"
7#include "testing/gtest/include/gtest/gtest.h"
8
9namespace net {
10namespace test {
11
12class CubeRootTest : public ::testing::Test {
13 protected:
14  CubeRootTest() {
15  }
16};
17
18TEST_F(CubeRootTest, LowRoot) {
19  for (uint32 i = 1; i < 256; ++i) {
20    uint64 cube = i * i * i;
21    uint8 cube_root = CubeRoot::Root(cube);
22    EXPECT_EQ(i, cube_root);
23  }
24}
25
26TEST_F(CubeRootTest, HighRoot) {
27  // Test the range we will opperate in, 1300 to 130 000.
28  // We expect some loss in accuracy, accepting +-0.2%.
29  for (uint64 i = 1300; i < 20000; i += 100) {
30    uint64 cube = i * i * i;
31    uint32 cube_root = CubeRoot::Root(cube);
32    uint32 margin = cube_root >> 9;  // Calculate 0.2% roughly by
33                                     // dividing by 512.
34    EXPECT_LE(i - margin, cube_root);
35    EXPECT_GE(i + margin, cube_root);
36  }
37  for (uint64 i = 20000; i < 130000; i *= 2) {
38    uint64 cube = i * i * i;
39    uint32 cube_root = CubeRoot::Root(cube);
40    uint32 margin = cube_root >> 9;
41    EXPECT_LE(i - margin, cube_root);
42    EXPECT_GE(i + margin, cube_root);
43  }
44}
45
46}  // namespace test
47}  // namespace net
48