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Unified Diff: base/rand_util_unittest.cc

Issue 1647803004: Move base to DEPS (Closed) Base URL: git@github.com:domokit/mojo.git@master
Patch Set: Created 4 years, 11 months ago
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Index: base/rand_util_unittest.cc
diff --git a/base/rand_util_unittest.cc b/base/rand_util_unittest.cc
deleted file mode 100644
index 90690ec2dbb6464041e2e89e93fe606fd5c61cfa..0000000000000000000000000000000000000000
--- a/base/rand_util_unittest.cc
+++ /dev/null
@@ -1,144 +0,0 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "base/rand_util.h"
-
-#include <algorithm>
-#include <limits>
-
-#include "base/logging.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/time/time.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-namespace {
-
-const int kIntMin = std::numeric_limits<int>::min();
-const int kIntMax = std::numeric_limits<int>::max();
-
-} // namespace
-
-TEST(RandUtilTest, SameMinAndMax) {
- EXPECT_EQ(base::RandInt(0, 0), 0);
- EXPECT_EQ(base::RandInt(kIntMin, kIntMin), kIntMin);
- EXPECT_EQ(base::RandInt(kIntMax, kIntMax), kIntMax);
-}
-
-TEST(RandUtilTest, RandDouble) {
- // Force 64-bit precision, making sure we're not in a 80-bit FPU register.
- volatile double number = base::RandDouble();
- EXPECT_GT(1.0, number);
- EXPECT_LE(0.0, number);
-}
-
-TEST(RandUtilTest, RandBytes) {
- const size_t buffer_size = 50;
- char buffer[buffer_size];
- memset(buffer, 0, buffer_size);
- base::RandBytes(buffer, buffer_size);
- std::sort(buffer, buffer + buffer_size);
- // Probability of occurrence of less than 25 unique bytes in 50 random bytes
- // is below 10^-25.
- EXPECT_GT(std::unique(buffer, buffer + buffer_size) - buffer, 25);
-}
-
-TEST(RandUtilTest, RandBytesAsString) {
- std::string random_string = base::RandBytesAsString(1);
- EXPECT_EQ(1U, random_string.size());
- random_string = base::RandBytesAsString(145);
- EXPECT_EQ(145U, random_string.size());
- char accumulator = 0;
- for (size_t i = 0; i < random_string.size(); ++i)
- accumulator |= random_string[i];
- // In theory this test can fail, but it won't before the universe dies of
- // heat death.
- EXPECT_NE(0, accumulator);
-}
-
-// Make sure that it is still appropriate to use RandGenerator in conjunction
-// with std::random_shuffle().
-TEST(RandUtilTest, RandGeneratorForRandomShuffle) {
- EXPECT_EQ(base::RandGenerator(1), 0U);
- EXPECT_LE(std::numeric_limits<ptrdiff_t>::max(),
- std::numeric_limits<int64>::max());
-}
-
-TEST(RandUtilTest, RandGeneratorIsUniform) {
- // Verify that RandGenerator has a uniform distribution. This is a
- // regression test that consistently failed when RandGenerator was
- // implemented this way:
- //
- // return base::RandUint64() % max;
- //
- // A degenerate case for such an implementation is e.g. a top of
- // range that is 2/3rds of the way to MAX_UINT64, in which case the
- // bottom half of the range would be twice as likely to occur as the
- // top half. A bit of calculus care of jar@ shows that the largest
- // measurable delta is when the top of the range is 3/4ths of the
- // way, so that's what we use in the test.
- const uint64 kTopOfRange = (std::numeric_limits<uint64>::max() / 4ULL) * 3ULL;
- const uint64 kExpectedAverage = kTopOfRange / 2ULL;
- const uint64 kAllowedVariance = kExpectedAverage / 50ULL; // +/- 2%
- const int kMinAttempts = 1000;
- const int kMaxAttempts = 1000000;
-
- double cumulative_average = 0.0;
- int count = 0;
- while (count < kMaxAttempts) {
- uint64 value = base::RandGenerator(kTopOfRange);
- cumulative_average = (count * cumulative_average + value) / (count + 1);
-
- // Don't quit too quickly for things to start converging, or we may have
- // a false positive.
- if (count > kMinAttempts &&
- kExpectedAverage - kAllowedVariance < cumulative_average &&
- cumulative_average < kExpectedAverage + kAllowedVariance) {
- break;
- }
-
- ++count;
- }
-
- ASSERT_LT(count, kMaxAttempts) << "Expected average was " <<
- kExpectedAverage << ", average ended at " << cumulative_average;
-}
-
-TEST(RandUtilTest, RandUint64ProducesBothValuesOfAllBits) {
- // This tests to see that our underlying random generator is good
- // enough, for some value of good enough.
- uint64 kAllZeros = 0ULL;
- uint64 kAllOnes = ~kAllZeros;
- uint64 found_ones = kAllZeros;
- uint64 found_zeros = kAllOnes;
-
- for (size_t i = 0; i < 1000; ++i) {
- uint64 value = base::RandUint64();
- found_ones |= value;
- found_zeros &= value;
-
- if (found_zeros == kAllZeros && found_ones == kAllOnes)
- return;
- }
-
- FAIL() << "Didn't achieve all bit values in maximum number of tries.";
-}
-
-// Benchmark test for RandBytes(). Disabled since it's intentionally slow and
-// does not test anything that isn't already tested by the existing RandBytes()
-// tests.
-TEST(RandUtilTest, DISABLED_RandBytesPerf) {
- // Benchmark the performance of |kTestIterations| of RandBytes() using a
- // buffer size of |kTestBufferSize|.
- const int kTestIterations = 10;
- const size_t kTestBufferSize = 1 * 1024 * 1024;
-
- scoped_ptr<uint8[]> buffer(new uint8[kTestBufferSize]);
- const base::TimeTicks now = base::TimeTicks::Now();
- for (int i = 0; i < kTestIterations; ++i)
- base::RandBytes(buffer.get(), kTestBufferSize);
- const base::TimeTicks end = base::TimeTicks::Now();
-
- LOG(INFO) << "RandBytes(" << kTestBufferSize << ") took: "
- << (end - now).InMicroseconds() << "µs";
-}
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