faux-folly/folly/test/DeterministicScheduleTest.cpp

/*
 * Copyright 2015 Facebook, Inc.
 *
 * 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 <folly/test/DeterministicSchedule.h>

#include <gflags/gflags.h>
#include <gtest/gtest.h>

using namespace folly::test;

TEST(DeterministicSchedule, uniform) {
  auto p = DeterministicSchedule::uniform(0);
  int buckets[10] = {};
  for (int i = 0; i < 100000; ++i) {
    buckets[p(10)]++;
  }
  for (int i = 0; i < 10; ++i) {
    EXPECT_TRUE(buckets[i] > 9000);
  }
}

TEST(DeterministicSchedule, uniformSubset) {
  auto ps = DeterministicSchedule::uniformSubset(0, 3, 100);
  int buckets[10] = {};
  std::set<int> seen;
  for (int i = 0; i < 100000; ++i) {
    if (i > 0 && (i % 100) == 0) {
      EXPECT_EQ(seen.size(), 3);
      seen.clear();
    }
    int x = ps(10);
    seen.insert(x);
    EXPECT_TRUE(seen.size() <= 3);
    buckets[x]++;
  }
  for (int i = 0; i < 10; ++i) {
    EXPECT_TRUE(buckets[i] > 9000);
  }
}

int main(int argc, char** argv) {
  testing::InitGoogleTest(&argc, argv);
  gflags::ParseCommandLineFlags(&argc, &argv, true);
  return RUN_ALL_TESTS();
}