AU: Beginnings of delta support

src/platform/update_engine/file_writer_unittest.cc

 // Copyright (c) 2009 The Chromium OS 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 <errno.h>
 #include <string.h>
 #include <unistd.h>
 #include <string>
 #include <vector>
 #include <gtest/gtest.h>
 #include "update_engine/file_writer.h"
 #include "update_engine/test_utils.h"
+#include "update_engine/utils.h"
 
 using std::string;
 using std::vector;
 
 namespace chromeos_update_engine {
 
 class FileWriterTest : public ::testing::Test { };
 
 TEST(FileWriterTest, SimpleTest) {
   DirectFileWriter file_writer;
   const string path("/tmp/FileWriterTest");
   ASSERT_EQ(0, file_writer.Open(path.c_str(),
                                 O_CREAT | O_LARGEFILE | O_TRUNC | O_WRONLY,
                                 0644));
   ASSERT_EQ(4, file_writer.Write("test", 4));
-  vector<char> actual_data = ReadFile(path);
+  vector<char> actual_data;
+  EXPECT_TRUE(utils::ReadFile(path, &actual_data));
 
   EXPECT_FALSE(memcmp("test", &actual_data[0], actual_data.size()));
   EXPECT_EQ(0, file_writer.Close());
   unlink(path.c_str());
 }
 
 TEST(FileWriterTest, ErrorTest) {
   DirectFileWriter file_writer;
   const string path("/tmp/ENOENT/FileWriterTest");
   EXPECT_EQ(-ENOENT, file_writer.Open(path.c_str(),
                                       O_CREAT | O_LARGEFILE | O_TRUNC, 0644));
 }
 
 TEST(FileWriterTest, WriteErrorTest) {
   DirectFileWriter file_writer;
   const string path("/tmp/FileWriterTest");
   EXPECT_EQ(0, file_writer.Open(path.c_str(),
                                 O_CREAT | O_LARGEFILE | O_TRUNC | O_RDONLY,
                                 0644));
   EXPECT_EQ(-EBADF, file_writer.Write("x", 1));
   EXPECT_EQ(0, file_writer.Close());
 }
 
 
 }  // namespace chromeos_update_engine