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Austin Schuh36244a12019-09-21 17:52:38 -07001// Copyright 2017 The Abseil Authors.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// https://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15#include "absl/random/seed_sequences.h"
16
17#include <iterator>
18#include <random>
19
20#include "gmock/gmock.h"
21#include "gtest/gtest.h"
22#include "absl/random/internal/nonsecure_base.h"
23#include "absl/random/random.h"
24namespace {
25
26TEST(SeedSequences, Examples) {
27 {
28 absl::SeedSeq seed_seq({1, 2, 3});
29 absl::BitGen bitgen(seed_seq);
30
31 EXPECT_NE(0, bitgen());
32 }
33 {
34 absl::BitGen engine;
35 auto seed_seq = absl::CreateSeedSeqFrom(&engine);
36 absl::BitGen bitgen(seed_seq);
37
38 EXPECT_NE(engine(), bitgen());
39 }
40 {
41 auto seed_seq = absl::MakeSeedSeq();
42 std::mt19937 random(seed_seq);
43
44 EXPECT_NE(0, random());
45 }
46}
47
48TEST(CreateSeedSeqFrom, CompatibleWithStdTypes) {
49 using ExampleNonsecureURBG =
50 absl::random_internal::NonsecureURBGBase<std::minstd_rand0>;
51
52 // Construct a URBG instance.
53 ExampleNonsecureURBG rng;
54
55 // Construct a Seed Sequence from its variates.
56 auto seq_from_rng = absl::CreateSeedSeqFrom(&rng);
57
58 // Ensure that another URBG can be validly constructed from the Seed Sequence.
59 std::mt19937_64{seq_from_rng};
60}
61
62TEST(CreateSeedSeqFrom, CompatibleWithBitGenerator) {
63 // Construct a URBG instance.
64 absl::BitGen rng;
65
66 // Construct a Seed Sequence from its variates.
67 auto seq_from_rng = absl::CreateSeedSeqFrom(&rng);
68
69 // Ensure that another URBG can be validly constructed from the Seed Sequence.
70 std::mt19937_64{seq_from_rng};
71}
72
73TEST(CreateSeedSeqFrom, CompatibleWithInsecureBitGen) {
74 // Construct a URBG instance.
75 absl::InsecureBitGen rng;
76
77 // Construct a Seed Sequence from its variates.
78 auto seq_from_rng = absl::CreateSeedSeqFrom(&rng);
79
80 // Ensure that another URBG can be validly constructed from the Seed Sequence.
81 std::mt19937_64{seq_from_rng};
82}
83
84TEST(CreateSeedSeqFrom, CompatibleWithRawURBG) {
85 // Construct a URBG instance.
86 std::random_device urandom;
87
88 // Construct a Seed Sequence from its variates, using 64b of seed-material.
89 auto seq_from_rng = absl::CreateSeedSeqFrom(&urandom);
90
91 // Ensure that another URBG can be validly constructed from the Seed Sequence.
92 std::mt19937_64{seq_from_rng};
93}
94
95template <typename URBG>
96void TestReproducibleVariateSequencesForNonsecureURBG() {
97 const size_t kNumVariates = 1000;
98
99 // Master RNG instance.
100 URBG rng;
101 // Reused for both RNG instances.
102 auto reusable_seed = absl::CreateSeedSeqFrom(&rng);
103
104 typename URBG::result_type variates[kNumVariates];
105 {
106 URBG child(reusable_seed);
107 for (auto& variate : variates) {
108 variate = child();
109 }
110 }
111 // Ensure that variate-sequence can be "replayed" by identical RNG.
112 {
113 URBG child(reusable_seed);
114 for (auto& variate : variates) {
115 ASSERT_EQ(variate, child());
116 }
117 }
118}
119
120TEST(CreateSeedSeqFrom, ReproducesVariateSequencesForInsecureBitGen) {
121 TestReproducibleVariateSequencesForNonsecureURBG<absl::InsecureBitGen>();
122}
123
124TEST(CreateSeedSeqFrom, ReproducesVariateSequencesForBitGenerator) {
125 TestReproducibleVariateSequencesForNonsecureURBG<absl::BitGen>();
126}
127} // namespace