libc/test/src/stdlib/rand_test.cpp

   1 //===-- Unittests for rand ------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "src/stdlib/rand.h"
  10 #include "src/stdlib/srand.h"
  11 #include "test/UnitTest/Test.h"
  12
  13 #include <stddef.h>
  14 #include <stdlib.h>
  15
  16 TEST(LlvmLibcRandTest, UnsetSeed) {
  17   static int vals[1000];
  18
  19   for (size_t i = 0; i < 1000; ++i) {
  20     int val = LIBC_NAMESPACE::rand();
  21     ASSERT_GE(val, 0);
  22     ASSERT_LE(val, RAND_MAX);
  23     vals[i] = val;
  24   }
  25
  26   // FIXME: The GPU implementation cannot initialize the seed correctly.
  27 #ifndef LIBC_TARGET_ARCH_IS_GPU
  28   // The C standard specifies that if 'srand' is never called it should behave
  29   // as if 'srand' was called with a value of 1. If we seed the value with 1 we
  30   // should get the same sequence as the unseeded version.
  31   LIBC_NAMESPACE::srand(1);
  32   for (size_t i = 0; i < 1000; ++i)
  33     ASSERT_EQ(LIBC_NAMESPACE::rand(), vals[i]);
  34 #endif
  35 }
  36
  37 TEST(LlvmLibcRandTest, SetSeed) {
  38   const unsigned int SEED = 12344321;
  39   LIBC_NAMESPACE::srand(SEED);
  40   const size_t NUM_RESULTS = 10;
  41   int results[NUM_RESULTS];
  42   for (size_t i = 0; i < NUM_RESULTS; ++i) {
  43     results[i] = LIBC_NAMESPACE::rand();
  44     ASSERT_GE(results[i], 0);
  45     ASSERT_LE(results[i], RAND_MAX);
  46   }
  47
  48   // If the seed is set to the same value, it should give the same sequence.
  49   LIBC_NAMESPACE::srand(SEED);
  50
  51   for (size_t i = 0; i < NUM_RESULTS; ++i) {
  52     int val = LIBC_NAMESPACE::rand();
  53     EXPECT_EQ(results[i], val);
  54   }
  55 }