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/*
* Copyright (C) 2021 Matthieu Gautier mgautier@kymeria.fr
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* is provided AS IS, WITHOUT ANY WARRANTY; without even the implied
* warranty of MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, and
* NON-INFRINGEMENT. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include "gtest/gtest.h"
namespace zim {
uint32_t randomNumber(uint32_t max);
};
using namespace zim;
namespace
{
TEST(Random, smallMax)
{
for(auto i=0; i<1000; i++) {
ASSERT_EQ(randomNumber(0), 0);
}
for(auto i=0; i<1000; i++) {
auto r = randomNumber(1);
ASSERT_TRUE(r>=0 && r<=1) << r;
}
}
TEST(Random, distribution)
{
const uint32_t NB_NUMBERS = 1000000;
const uint32_t NB_BUCKETS = 100;
const uint32_t BUCKET_SIZE = NB_NUMBERS/NB_BUCKETS;
const uint32_t MAX_RANDOM = 1000000;
std::vector<uint32_t> distribution(NB_BUCKETS);
for (auto i=0U; i<NB_NUMBERS; i++) {
auto r = randomNumber(MAX_RANDOM);
auto bucket_index = (float)r / MAX_RANDOM * NB_BUCKETS;
if (bucket_index == NB_BUCKETS) {
// This only happens when r == MAX_RANDOM.
bucket_index = NB_BUCKETS-1;
}
distribution[bucket_index]++;
}
// Each bucket should have around BUCKET_SIZE element.
// Test this is true at 10%
for(auto nbElement:distribution) {
ASSERT_GT(nbElement, BUCKET_SIZE*0.9);
ASSERT_LT(nbElement, BUCKET_SIZE*1.1);
}
}
};
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