// Copyright (c) 2017 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include "random.h"

#include "test/test_bitcoin.h"

#include <boost/test/unit_test.hpp>

BOOST_FIXTURE_TEST_SUITE(random_tests, BasicTestingSetup)

static const ssize_t MAX_TRIES = 1024;

BOOST_AUTO_TEST_CASE(osrandom_tests)
{
    /* This does not measure the quality of randomness, but it does test that
     * OSRandom() overwrites all 32 bytes of the output given a maximum
     * number of tries.
     */
    uint8_t data[NUM_OS_RANDOM_BYTES];
    bool overwritten[NUM_OS_RANDOM_BYTES] = {}; /* Tracks which bytes have been overwritten at least once */
    int num_overwritten;
    int tries = 0;
    /* Loop until all bytes have been overwritten at least once */
    do {
        memset(data, 0, NUM_OS_RANDOM_BYTES);
        GetOSRand(data);
        for (int x=0; x < NUM_OS_RANDOM_BYTES; ++x) {
            overwritten[x] |= (data[x] != 0);
        }

        num_overwritten = 0;
        for (int x=0; x < NUM_OS_RANDOM_BYTES; ++x) {
            if (overwritten[x]) {
                num_overwritten += 1;
            }
        }

        tries += 1;
    } while (num_overwritten < NUM_OS_RANDOM_BYTES && tries < MAX_TRIES);
    BOOST_CHECK(num_overwritten == NUM_OS_RANDOM_BYTES); /* If this failed, bailed out after too many tries */
}

BOOST_AUTO_TEST_SUITE_END()