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 15 TEST(LlvmLibcRandTest, UnsetSeed) { 16 static int vals[1000]; 17 18 for (size_t i = 0; i < 1000; ++i) { 19 int val = LIBC_NAMESPACE::rand(); 20 ASSERT_GE(val, 0); 21 ASSERT_LE(val, RAND_MAX); 22 vals[i] = val; 23 } 24 25 // The C standard specifies that if 'srand' is never called it should behave 26 // as if 'srand' was called with a value of 1. If we seed the value with 1 we 27 // should get the same sequence as the unseeded version. 28 LIBC_NAMESPACE::srand(1); 29 for (size_t i = 0; i < 1000; ++i) 30 ASSERT_EQ(LIBC_NAMESPACE::rand(), vals[i]); 31 } 32 33 TEST(LlvmLibcRandTest, SetSeed) { 34 const unsigned int SEED = 12344321; 35 LIBC_NAMESPACE::srand(SEED); 36 const size_t NUM_RESULTS = 10; 37 int results[NUM_RESULTS]; 38 for (size_t i = 0; i < NUM_RESULTS; ++i) { 39 results[i] = LIBC_NAMESPACE::rand(); 40 ASSERT_GE(results[i], 0); 41 ASSERT_LE(results[i], RAND_MAX); 42 } 43 44 // If the seed is set to the same value, it should give the same sequence. 45 LIBC_NAMESPACE::srand(SEED); 46 47 for (size_t i = 0; i < NUM_RESULTS; ++i) { 48 int val = LIBC_NAMESPACE::rand(); 49 EXPECT_EQ(results[i], val); 50 } 51 } 52