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      1 /*
      2  * Copyright (C) 2017 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include <limits>
     18 #include "gtest/gtest.h"
     19 
     20 #include "include/random_generator.h"
     21 
     22 template <typename TestType>
     23 class RandomGeneratorTest : public testing::Test {
     24  public:
     25   wifi_offload_test::RandomGenerator random_gen_;
     26 
     27   void GeneratedNumbersAreSmallerOrEqualTypeMaxValue() {
     28     uint64_t rand_val = random_gen_.get<TestType>();
     29     uint64_t max_val = std::numeric_limits<TestType>::max();
     30 
     31     EXPECT_TRUE(rand_val <= max_val);
     32   }
     33 
     34   void AllRandomGeneratorsGenerateTheSameSequence() {
     35     constexpr size_t num_values = 10;
     36     TestType rand_values[num_values];
     37 
     38     for (size_t i = 0; i < num_values; i++) {
     39       rand_values[i] = random_gen_.get<TestType>();
     40     }
     41 
     42     wifi_offload_test::RandomGenerator another_random_gen_;
     43     for (size_t i = 0; i < num_values; i++) {
     44       ASSERT_EQ(rand_values[i], another_random_gen_.get<TestType>());
     45     }
     46   }
     47 
     48   void AfterResetGeneratesTheSameSequence() {
     49     constexpr size_t num_values = 10;
     50     TestType rand_values[num_values];
     51 
     52     for (size_t i = 0; i < num_values; i++) {
     53       rand_values[i] = random_gen_.get<TestType>();
     54     }
     55 
     56     random_gen_.Reset();
     57     for (size_t i = 0; i < num_values; i++) {
     58       ASSERT_EQ(rand_values[i], random_gen_.get<TestType>());
     59     }
     60   }
     61 
     62   void GeneratesDifferentNumbersIn8Bytes() {
     63     constexpr size_t num_values = 10;
     64     uint64_t rand_values[num_values];
     65 
     66     constexpr size_t repeats_to_fill_8_bytes =
     67         sizeof(uint64_t) / sizeof(TestType);
     68     constexpr size_t shift_size =
     69         (sizeof(TestType) * 8) % (sizeof(uint64_t) * 8);
     70 
     71     for (size_t i = 0; i < num_values; i++) {
     72       rand_values[i] = 0;
     73       for (size_t j = 0; j < repeats_to_fill_8_bytes; j++) {
     74         rand_values[i] <<= shift_size;
     75         rand_values[i] |= random_gen_.get<TestType>();
     76       }
     77     }
     78 
     79     // The probability of choosing equal random numbers out of 2 ^ 64 values
     80     // is "extremely" small. Smaller than the change of memory failure.
     81     for (size_t i = 0; i < num_values - 1; i++) {
     82       for (size_t j = i + 1; j < num_values; j++) {
     83         ASSERT_NE(rand_values[i], rand_values[j]);
     84       }
     85     }
     86   }
     87 };
     88 
     89 typedef testing::Types<uint8_t, uint16_t, uint32_t, uint64_t> Implementations;
     90 
     91 TYPED_TEST_CASE(RandomGeneratorTest, Implementations);
     92 
     93 TYPED_TEST(RandomGeneratorTest, GeneratedNumbersAreSmallerOrEqualTypeMaxValue) {
     94   this->GeneratedNumbersAreSmallerOrEqualTypeMaxValue();
     95 }
     96 
     97 TYPED_TEST(RandomGeneratorTest, AllRandomGeneratorsGenerateTheSameSequence) {
     98   this->AllRandomGeneratorsGenerateTheSameSequence();
     99 }
    100 
    101 TYPED_TEST(RandomGeneratorTest, AfterResetGeneratesTheSameSequence) {
    102   this->AfterResetGeneratesTheSameSequence();
    103 }
    104 
    105 TYPED_TEST(RandomGeneratorTest, GeneratesDifferentNumbersIn8Bytes) {
    106   this->GeneratesDifferentNumbersIn8Bytes();
    107 }
    108