1 // Copyright 2019 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 "util/integer_division.h"
6
7 #include <chrono>
8
9 #include "gtest/gtest.h"
10
11 namespace openscreen {
12 namespace {
13
14 constexpr int kDenominators[2] = {3, 4};
15
16 // Common test routine that tests one of the integer division functions using a
17 // fixed denominator and stepping, one-by-one, over a range of numerators around
18 // zero.
19 template <typename Input, typename Output>
TestRangeAboutZero(int denom,int range_of_numerators,int first_expected_result,Output (* function_to_test)(Input,Input))20 void TestRangeAboutZero(int denom,
21 int range_of_numerators,
22 int first_expected_result,
23 Output (*function_to_test)(Input, Input)) {
24 int expected_result = first_expected_result;
25 int count_until_next_change = denom;
26 for (int num = -range_of_numerators; num <= range_of_numerators; ++num) {
27 EXPECT_EQ(expected_result, function_to_test(Input(num), Input(denom)))
28 << "num=" << num << ", denom=" << denom;
29 EXPECT_EQ(expected_result, function_to_test(Input(-num), Input(-denom)))
30 << "num=" << (-num) << ", denom=" << (-denom);
31
32 --count_until_next_change;
33 if (count_until_next_change == 0) { // Next result will be one higher.
34 ++expected_result;
35 count_until_next_change = denom;
36 }
37 }
38 }
39
TEST(IntegerDivision,DividesAndRoundsUpInts)40 TEST(IntegerDivision, DividesAndRoundsUpInts) {
41 auto* const function_to_test = &DivideRoundingUp<int>;
42 for (int denom : kDenominators) {
43 TestRangeAboutZero(denom, denom == 3 ? 11 : 15, -3, function_to_test);
44 }
45 }
46
TEST(IntegerDivision,DividesAndRoundsUpChronoDurations)47 TEST(IntegerDivision, DividesAndRoundsUpChronoDurations) {
48 auto* const function_to_test = &DivideRoundingUp<std::chrono::milliseconds>;
49 for (int denom : kDenominators) {
50 TestRangeAboutZero(denom, denom == 3 ? 11 : 15, -3, function_to_test);
51 }
52 }
53
54 // Assumption: DivideRoundingUp() is working (tested by the above two tests).
TEST(IntegerDivision,DividesPositivesAndRoundsUp)55 TEST(IntegerDivision, DividesPositivesAndRoundsUp) {
56 for (int num = 0; num <= 6; ++num) {
57 for (int denom = 1; denom <= 6; ++denom) {
58 EXPECT_EQ(DivideRoundingUp(num, denom),
59 DividePositivesRoundingUp(num, denom));
60 }
61 }
62 }
63
TEST(IntegerDivision,DividesAndRoundsNearestInts)64 TEST(IntegerDivision, DividesAndRoundsNearestInts) {
65 auto* const function_to_test = &DivideRoundingNearest<int>;
66 for (int denom : kDenominators) {
67 TestRangeAboutZero(denom, denom == 3 ? 10 : 14, -3, function_to_test);
68 }
69 }
70
TEST(IntegerDivision,DividesAndRoundsNearestChronoDurations)71 TEST(IntegerDivision, DividesAndRoundsNearestChronoDurations) {
72 auto* const function_to_test =
73 &DivideRoundingNearest<std::chrono::milliseconds>;
74 for (int denom : kDenominators) {
75 TestRangeAboutZero(denom, denom == 3 ? 10 : 14, -3, function_to_test);
76 }
77 }
78
79 // Assumption: DivideRoundingNearest() is working (tested by the above two
80 // tests).
TEST(IntegerDivision,DividesPositivesAndRoundsNearest)81 TEST(IntegerDivision, DividesPositivesAndRoundsNearest) {
82 for (int num = 0; num <= 6; ++num) {
83 for (int denom = 1; denom <= 6; ++denom) {
84 EXPECT_EQ(DivideRoundingNearest(num, denom),
85 DividePositivesRoundingNearest(num, denom));
86 }
87 }
88 }
89
90 } // namespace
91 } // namespace openscreen
92