Split mojo/public/cpp/system/tests/core_unittest.cc, part 2 (of 2, apparently).

mojo/public/cpp/system/tests/buffer_unittest.cc

+// Copyright 2016 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.
+
+// This file tests the C++ wrappers in mojo/public/cpp/system/buffer.h.
+
+#include "mojo/public/cpp/system/buffer.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace mojo {
+namespace {
+
+TEST(BufferTest, BasicSharedBuffer) {
+  // Cursory compilation test of |MakeScopedHandle()| with shared buffer
+  // handles.
+  EXPECT_FALSE(MakeScopedHandle(SharedBufferHandle()).is_valid());
+
+  ScopedSharedBufferHandle shared_buffer;
+  EXPECT_EQ(MOJO_RESULT_OK, CreateSharedBuffer(nullptr, 100u, &shared_buffer));
+  EXPECT_TRUE(shared_buffer.is_valid());
+
+  void* pointer = nullptr;
+  EXPECT_EQ(MOJO_RESULT_OK, MapBuffer(shared_buffer.get(), 0, 100u, &pointer,
+                                      MOJO_MAP_BUFFER_FLAG_NONE));
+  EXPECT_NE(pointer, nullptr);
+
+  // Just try writing to it.
+  *static_cast<char*>(pointer) = 'x';
+
+  shared_buffer.reset();
+
+  // Can still write to it even after the handle is closed.
+  *static_cast<char*>(pointer) = 'y';
+
+  EXPECT_EQ(MOJO_RESULT_OK, UnmapBuffer(pointer));
+}
+
+}  // namespace
+}  // namespace mojo