src/kudu/util/random_util-test.cc

// Copyright 2014 Cloudera, 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 "kudu/util/random_util.h"

#include <algorithm>
#include <cmath>
#include <cstring>

#include "kudu/util/random.h"
#include "kudu/util/test_util.h"

namespace kudu {

class RandomUtilTest : public KuduTest {
 protected:
  RandomUtilTest() : rng_(SeedRandom()) {}

  Random rng_;

  static const int kLenMax = 100;
  static const int kNumTrials = 100;
};

namespace {

// Checks string defined at start is set to \0 everywhere but [from, to)
void CheckEmpty(char* start, int from, int to, int stop) {
  DCHECK_LE(0, from);
  DCHECK_LE(from, to);
  DCHECK_LE(to, stop);
  for (int j = 0; (j == from ? j = to : j) < stop; ++j) {
    CHECK_EQ(start[j], '\0') << "Index " << j << " not null after defining"
                             << "indices [" << from << "," << to << ") of "
                             << "a nulled string [0," << stop << ").";
  }
}

} // anonymous namespace

// Makes sure that RandomString only writes the specified amount
TEST_F(RandomUtilTest, TestRandomString) {
  char start[kLenMax];

  for (int i = 0; i < kNumTrials; ++i) {
    memset(start, '\0', kLenMax);
    int to = rng_.Uniform(kLenMax + 1);
    int from = rng_.Uniform(to + 1);
    RandomString(start + from, to - from, &rng_);
    CheckEmpty(start, from, to, kLenMax);
  }

  // Corner case
  memset(start, '\0', kLenMax);
  RandomString(start, 0, &rng_);
  CheckEmpty(start, 0, 0, kLenMax);
}

} // namespace kudu