Add missing overflow handling to base::RandInt().

base/rand_util_unittest.cc

 // 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) {
+TEST(RandUtilTest, RandInt) {
   EXPECT_EQ(base::RandInt(0, 0), 0);
   EXPECT_EQ(base::RandInt(kIntMin, kIntMin), kIntMin);
   EXPECT_EQ(base::RandInt(kIntMax, kIntMax), kIntMax);
+
+  // Check that the DCHECKS in RandInt() don't fire due to internal overflow.
+  // There was a 50% chance of that happening, so calling it 40 times means
+  // the chances of this passing by accident are tiny (9e-13).
+  for (int i = 0; i < 40; ++i)
+    base::RandInt(kIntMin, 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) {
@@ skipping 99 matching lines @@
 
   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";
 }