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TestRollingNumber.cpp (3258B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
      3 /* This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
      5 * You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 #include <gtest/gtest.h>
      8 
      9 #include <cstdint>
     10 #include <type_traits>
     11 
     12 #include "RollingNumber.h"
     13 
     14 using RN8 = mozilla::RollingNumber<uint8_t>;
     15 
     16 TEST(RollingNumber, Value)
     17 {
     18  // Value type should reflect template argument.
     19  static_assert(std::is_same_v<RN8::ValueType, uint8_t>);
     20 
     21  // Default init to 0.
     22  const RN8 n;
     23  // Access through Value().
     24  EXPECT_EQ(0, n.Value());
     25 
     26  // Conversion constructor.
     27  RN8 n42{42};
     28  EXPECT_EQ(42, n42.Value());
     29 
     30  // Copy Constructor.
     31  RN8 n42Copied{n42};
     32  EXPECT_EQ(42, n42Copied.Value());
     33 
     34  // Assignment construction.
     35  RN8 n42Assigned = n42;
     36  EXPECT_EQ(42, n42Assigned.Value());
     37 
     38  // Assignment.
     39  n42 = n;
     40  EXPECT_EQ(0, n42.Value());
     41 }
     42 
     43 TEST(RollingNumber, Operations)
     44 {
     45  RN8 n;
     46  EXPECT_EQ(0, n.Value());
     47 
     48  RN8 nPreInc = ++n;
     49  EXPECT_EQ(1, n.Value());
     50  EXPECT_EQ(1, nPreInc.Value());
     51 
     52  RN8 nPostInc = n++;
     53  EXPECT_EQ(2, n.Value());
     54  EXPECT_EQ(1, nPostInc.Value());
     55 
     56  RN8 nPreDec = --n;
     57  EXPECT_EQ(1, n.Value());
     58  EXPECT_EQ(1, nPreDec.Value());
     59 
     60  RN8 nPostDec = n--;
     61  EXPECT_EQ(0, n.Value());
     62  EXPECT_EQ(1, nPostDec.Value());
     63 
     64  RN8 nPlus = n + 10;
     65  EXPECT_EQ(0, n.Value());
     66  EXPECT_EQ(10, nPlus.Value());
     67 
     68  n += 20;
     69  EXPECT_EQ(20, n.Value());
     70 
     71  RN8 nMinus = n - 2;
     72  EXPECT_EQ(20, n.Value());
     73  EXPECT_EQ(18, nMinus.Value());
     74 
     75  n -= 5;
     76  EXPECT_EQ(15, n.Value());
     77 
     78  uint8_t diff = nMinus - n;
     79  EXPECT_EQ(3, diff);
     80 
     81  // Overflows.
     82  n = RN8(0);
     83  EXPECT_EQ(0, n.Value());
     84  n--;
     85  EXPECT_EQ(255, n.Value());
     86  n++;
     87  EXPECT_EQ(0, n.Value());
     88  n -= 10;
     89  EXPECT_EQ(246, n.Value());
     90  n += 20;
     91  EXPECT_EQ(10, n.Value());
     92 }
     93 
     94 TEST(RollingNumber, Comparisons)
     95 {
     96  uint8_t i = 0;
     97  do {
     98    RN8 n{i};
     99    EXPECT_EQ(i, n.Value());
    100    EXPECT_TRUE(n == n);
    101    EXPECT_FALSE(n != n);
    102    EXPECT_FALSE(n < n);
    103    EXPECT_TRUE(n <= n);
    104    EXPECT_FALSE(n > n);
    105    EXPECT_TRUE(n >= n);
    106 
    107    RN8 same = n;
    108    EXPECT_TRUE(n == same);
    109    EXPECT_FALSE(n != same);
    110    EXPECT_FALSE(n < same);
    111    EXPECT_TRUE(n <= same);
    112    EXPECT_FALSE(n > same);
    113    EXPECT_TRUE(n >= same);
    114 
    115 #ifdef DEBUG
    116    // In debug builds, we are only allowed a quarter of the type range.
    117    const uint8_t maxDiff = 255 / 4;
    118 #else
    119    // In non-debug builds, we can go half-way up or down the type range, and
    120    // still conserve the expected ordering.
    121    const uint8_t maxDiff = 255 / 2;
    122 #endif
    123    for (uint8_t add = 1; add <= maxDiff; ++add) {
    124      RN8 bigger = n + add;
    125      EXPECT_FALSE(n == bigger);
    126      EXPECT_TRUE(n != bigger);
    127      EXPECT_TRUE(n < bigger);
    128      EXPECT_TRUE(n <= bigger);
    129      EXPECT_FALSE(n > bigger);
    130      EXPECT_FALSE(n >= bigger);
    131    }
    132 
    133    for (uint8_t sub = 1; sub <= maxDiff; ++sub) {
    134      RN8 smaller = n - sub;
    135      EXPECT_FALSE(n == smaller);
    136      EXPECT_TRUE(n != smaller);
    137      EXPECT_FALSE(n < smaller);
    138      EXPECT_FALSE(n <= smaller);
    139      EXPECT_TRUE(n > smaller);
    140      EXPECT_TRUE(n >= smaller);
    141    }
    142 
    143    ++i;
    144  } while (i != 0);
    145 }