Disable automatic update checks if booting from a removable device.

utils_unittest.cc

 // Copyright (c) 2010 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 <sys/stat.h>
 #include <sys/types.h>
 #include <errno.h>
 #include <string>
 #include <vector>
 #include <gtest/gtest.h>
@@ skipping 115 matching lines @@
   const string original = "/foo.XXXXXX";
   const string result = utils::TempFilename(original);
   EXPECT_EQ(original.size(), result.size());
   EXPECT_TRUE(utils::StringHasPrefix(result, "/foo."));
   EXPECT_FALSE(utils::StringHasSuffix(result, "XXXXXX"));
 }
 
 TEST(UtilsTest, RootDeviceTest) {
   EXPECT_EQ("/dev/sda", utils::RootDevice("/dev/sda3"));
   EXPECT_EQ("/dev/mmc0", utils::RootDevice("/dev/mmc0p3"));
+  EXPECT_EQ("", utils::RootDevice("/dev/foo/bar"));
+  EXPECT_EQ("", utils::RootDevice("/"));
+  EXPECT_EQ("", utils::RootDevice(""));
+}
+
+TEST(UtilsTest, SysfsBlockDeviceTest) {
+  EXPECT_EQ("/sys/block/sda", utils::SysfsBlockDevice("/dev/sda"));
+  EXPECT_EQ("", utils::SysfsBlockDevice("/foo/sda"));
+  EXPECT_EQ("", utils::SysfsBlockDevice("/dev/foo/bar"));
+  EXPECT_EQ("", utils::SysfsBlockDevice("/"));
+  EXPECT_EQ("", utils::SysfsBlockDevice("./"));
+  EXPECT_EQ("", utils::SysfsBlockDevice(""));
+}
+
+TEST(UtilsTest, IsRemovableDeviceTest) {
+  EXPECT_FALSE(utils::IsRemovableDevice(""));
+  EXPECT_FALSE(utils::IsRemovableDevice("/dev/non-existent-device"));
 }
 
 TEST(UtilsTest, PartitionNumberTest) {
   EXPECT_EQ("3", utils::PartitionNumber("/dev/sda3"));
   EXPECT_EQ("3", utils::PartitionNumber("/dev/mmc0p3"));
 }
 
 }  // namespace chromeos_update_engine