TestRandomNum.cpp (1987B)
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 "mozilla/RandomNum.h" 8 #include <vector> 9 10 /* 11 12 * We're going to check that random number generation is sane on a basic 13 * level - That is, we want to check that the function returns success 14 * and doesn't just keep returning the same number. 15 * 16 * Note that there are many more tests that could be done, but to really test 17 * a PRNG we'd probably need to generate a large set of randoms and 18 * perform statistical analysis on them. Maybe that's worth doing eventually? 19 * 20 * For now we should be fine just performing a dumb test of generating 5 21 * numbers and making sure they're all unique. In theory, it is possible for 22 * this test to report a false negative, but with 5 numbers the probability 23 * is less than one-in-a-trillion. 24 * 25 */ 26 27 #define NUM_RANDOMS_TO_GENERATE 5 28 29 using mozilla::Maybe; 30 using mozilla::RandomUint64; 31 32 static uint64_t getRandomUint64OrDie() { 33 Maybe<uint64_t> maybeRandomNum = RandomUint64(); 34 35 MOZ_RELEASE_ASSERT(maybeRandomNum.isSome()); 36 37 return maybeRandomNum.value(); 38 } 39 40 static void TestRandomUint64() { 41 // The allocator uses RandomNum.h too, but its initialization path allocates 42 // memory. While the allocator itself handles the situation, we can't, so 43 // we make sure to use an allocation before getting a Random number ourselves. 44 std::vector<uint64_t> randomsList; 45 randomsList.reserve(NUM_RANDOMS_TO_GENERATE); 46 47 for (uint8_t i = 0; i < NUM_RANDOMS_TO_GENERATE; ++i) { 48 uint64_t randomNum = getRandomUint64OrDie(); 49 50 for (uint64_t num : randomsList) { 51 MOZ_RELEASE_ASSERT(randomNum != num); 52 } 53 54 randomsList.push_back(randomNum); 55 } 56 } 57 58 int main() { 59 TestRandomUint64(); 60 return 0; 61 }