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//
// Copyright (C) 2014 The Android Open Source Project
//
// 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
//
// http://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 "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