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// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "absl/random/seed_sequences.h"
#include <iterator>
#include <random>
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "absl/random/internal/nonsecure_base.h"
#include "absl/random/random.h"
namespace {
TEST(SeedSequences, Examples) {
{
absl::SeedSeq seed_seq({1, 2, 3});
absl::BitGen bitgen(seed_seq);
EXPECT_NE(0, bitgen());
}
{
absl::BitGen engine;
auto seed_seq = absl::CreateSeedSeqFrom(&engine);
absl::BitGen bitgen(seed_seq);
EXPECT_NE(engine(), bitgen());
}
{
auto seed_seq = absl::MakeSeedSeq();
std::mt19937 random(seed_seq);
EXPECT_NE(0, random());
}
}
TEST(CreateSeedSeqFrom, CompatibleWithStdTypes) {
using ExampleNonsecureURBG =
absl::random_internal::NonsecureURBGBase<std::minstd_rand0>;
// Construct a URBG instance.
ExampleNonsecureURBG rng;
// Construct a Seed Sequence from its variates.
auto seq_from_rng = absl::CreateSeedSeqFrom(&rng);
// Ensure that another URBG can be validly constructed from the Seed Sequence.
std::mt19937_64{seq_from_rng};
}
TEST(CreateSeedSeqFrom, CompatibleWithBitGenerator) {
// Construct a URBG instance.
absl::BitGen rng;
// Construct a Seed Sequence from its variates.
auto seq_from_rng = absl::CreateSeedSeqFrom(&rng);
// Ensure that another URBG can be validly constructed from the Seed Sequence.
std::mt19937_64{seq_from_rng};
}
TEST(CreateSeedSeqFrom, CompatibleWithInsecureBitGen) {
// Construct a URBG instance.
absl::InsecureBitGen rng;
// Construct a Seed Sequence from its variates.
auto seq_from_rng = absl::CreateSeedSeqFrom(&rng);
// Ensure that another URBG can be validly constructed from the Seed Sequence.
std::mt19937_64{seq_from_rng};
}
TEST(CreateSeedSeqFrom, CompatibleWithRawURBG) {
// Construct a URBG instance.
std::random_device urandom;
// Construct a Seed Sequence from its variates, using 64b of seed-material.
auto seq_from_rng = absl::CreateSeedSeqFrom(&urandom);
// Ensure that another URBG can be validly constructed from the Seed Sequence.
std::mt19937_64{seq_from_rng};
}
template <typename URBG>
void TestReproducibleVariateSequencesForNonsecureURBG() {
const size_t kNumVariates = 1000;
// Master RNG instance.
URBG rng;
// Reused for both RNG instances.
auto reusable_seed = absl::CreateSeedSeqFrom(&rng);
typename URBG::result_type variates[kNumVariates];
{
URBG child(reusable_seed);
for (auto& variate : variates) {
variate = child();
}
}
// Ensure that variate-sequence can be "replayed" by identical RNG.
{
URBG child(reusable_seed);
for (auto& variate : variates) {
ASSERT_EQ(variate, child());
}
}
}
TEST(CreateSeedSeqFrom, ReproducesVariateSequencesForInsecureBitGen) {
TestReproducibleVariateSequencesForNonsecureURBG<absl::InsecureBitGen>();
}
TEST(CreateSeedSeqFrom, ReproducesVariateSequencesForBitGenerator) {
TestReproducibleVariateSequencesForNonsecureURBG<absl::BitGen>();
}
} // namespace
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