Function TestNextRandom

BeefRT/gperftools/src/tests/sampler_test.cc:223–252

Testing that NextRandom generates uniform random numbers. Applies the Anderson-Darling test for uniformity

// random numbers.
// Applies the Anderson-Darling test for uniformity
void TestNextRandom(int n) {
  tcmalloc::Sampler sampler;
  sampler.Init(1);
  uint64_t x = 1;
  // This assumes that the prng returns 48 bit numbers
  uint64_t max_prng_value = static_cast<uint64_t>(1)<<48;
  // Initialize
  for (int i = 1; i <= 20; i++) {  // 20 mimics sampler.Init()
    x = sampler.NextRandom(x);
  }
  scoped_array<uint64_t> int_random_sample(new uint64_t[n]);
  // Collect samples
  for (int i = 0; i < n; i++) {
    int_random_sample[i] = x;
    x = sampler.NextRandom(x);
  }
  // First sort them...
  sort(int_random_sample.get(), int_random_sample.get() + n);
  scoped_array<double> random_sample(new double[n]);
  // Convert them to uniform randoms (in the range [0,1])
  for (int i = 0; i < n; i++) {
    random_sample[i] = static_cast<double>(int_random_sample[i])/max_prng_value;
  }
  // Now compute the Anderson-Darling statistic
  double ad_pvalue = AndersonDarlingTest(n, random_sample.get());
  LOG(INFO) << StringPrintf("pvalue for AndersonDarlingTest "
                            "with n= %d is p= %f\n", n, ad_pvalue);
  CHECK_GT(min(ad_pvalue, 1 - ad_pvalue), 0.0001);
  //           << StringPrintf("prng is not uniform, %d\n", n);
}


TEST(Sampler, TestNextRandom_MultipleValues) {