| // Copyright (c) 2014 The Chromium OS Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "update_engine/update_manager/prng.h" |
| |
| #include <vector> |
| |
| #include <gtest/gtest.h> |
| |
| using std::vector; |
| |
| namespace chromeos_update_manager { |
| |
| TEST(UmPRNGTest, ShouldBeDeterministic) { |
| PRNG a(42); |
| PRNG b(42); |
| |
| for (int i = 0; i < 1000; ++i) { |
| EXPECT_EQ(a.Rand(), b.Rand()) << "Iteration i=" << i; |
| } |
| } |
| |
| TEST(UmPRNGTest, SeedChangesGeneratedSequence) { |
| PRNG a(42); |
| PRNG b(5); |
| |
| vector<uint32_t> values_a; |
| vector<uint32_t> values_b; |
| |
| for (int i = 0; i < 100; ++i) { |
| values_a.push_back(a.Rand()); |
| values_b.push_back(b.Rand()); |
| } |
| EXPECT_NE(values_a, values_b); |
| } |
| |
| TEST(UmPRNGTest, IsNotConstant) { |
| PRNG prng(5); |
| |
| uint32_t initial_value = prng.Rand(); |
| bool prng_is_constant = true; |
| for (int i = 0; i < 100; ++i) { |
| if (prng.Rand() != initial_value) { |
| prng_is_constant = false; |
| break; |
| } |
| } |
| EXPECT_FALSE(prng_is_constant) << "After 100 iterations."; |
| } |
| |
| TEST(UmPRNGTest, RandCoversRange) { |
| PRNG a(42); |
| int hits[11] = { 0 }; |
| |
| for (int i = 0; i < 1000; i++) { |
| int r = a.RandMinMax(0, 10); |
| ASSERT_LE(0, r); |
| ASSERT_GE(10, r); |
| hits[r]++; |
| } |
| |
| for (auto& hit : hits) |
| EXPECT_LT(0, hit); |
| } |
| |
| } // namespace chromeos_update_manager |