diff --git a/common/test_utils.cc b/common/test_utils.cc
new file mode 100644
index 0000000..f89c448
--- /dev/null
+++ b/common/test_utils.cc
@@ -0,0 +1,268 @@
+//
+// Copyright (C) 2012 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include "update_engine/common/test_utils.h"
+
+#include <dirent.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/xattr.h>
+#include <unistd.h>
+
+#include <set>
+#include <string>
+#include <vector>
+
+#include <base/files/file_util.h>
+#include <base/format_macros.h>
+#include <base/logging.h>
+#include <base/strings/string_util.h>
+#include <base/strings/stringprintf.h>
+
+#include "update_engine/common/utils.h"
+#include "update_engine/payload_consumer/file_writer.h"
+
+using base::StringPrintf;
+using std::set;
+using std::string;
+using std::vector;
+
+namespace chromeos_update_engine {
+
+void PrintTo(const Extent& extent, ::std::ostream* os) {
+  *os << "(" << extent.start_block() << ", " << extent.num_blocks() << ")";
+}
+
+namespace test_utils {
+
+const char* const kMountPathTemplate = "UpdateEngineTests_mnt-XXXXXX";
+
+const uint8_t kRandomString[] = {
+  0xf2, 0xb7, 0x55, 0x92, 0xea, 0xa6, 0xc9, 0x57,
+  0xe0, 0xf8, 0xeb, 0x34, 0x93, 0xd9, 0xc4, 0x8f,
+  0xcb, 0x20, 0xfa, 0x37, 0x4b, 0x40, 0xcf, 0xdc,
+  0xa5, 0x08, 0x70, 0x89, 0x79, 0x35, 0xe2, 0x3d,
+  0x56, 0xa4, 0x75, 0x73, 0xa3, 0x6d, 0xd1, 0xd5,
+  0x26, 0xbb, 0x9c, 0x60, 0xbd, 0x2f, 0x5a, 0xfa,
+  0xb7, 0xd4, 0x3a, 0x50, 0xa7, 0x6b, 0x3e, 0xfd,
+  0x61, 0x2b, 0x3a, 0x31, 0x30, 0x13, 0x33, 0x53,
+  0xdb, 0xd0, 0x32, 0x71, 0x5c, 0x39, 0xed, 0xda,
+  0xb4, 0x84, 0xca, 0xbc, 0xbd, 0x78, 0x1c, 0x0c,
+  0xd8, 0x0b, 0x41, 0xe8, 0xe1, 0xe0, 0x41, 0xad,
+  0x03, 0x12, 0xd3, 0x3d, 0xb8, 0x75, 0x9b, 0xe6,
+  0xd9, 0x01, 0xd0, 0x87, 0xf4, 0x36, 0xfa, 0xa7,
+  0x0a, 0xfa, 0xc5, 0x87, 0x65, 0xab, 0x9a, 0x7b,
+  0xeb, 0x58, 0x23, 0xf0, 0xa8, 0x0a, 0xf2, 0x33,
+  0x3a, 0xe2, 0xe3, 0x35, 0x74, 0x95, 0xdd, 0x3c,
+  0x59, 0x5a, 0xd9, 0x52, 0x3a, 0x3c, 0xac, 0xe5,
+  0x15, 0x87, 0x6d, 0x82, 0xbc, 0xf8, 0x7d, 0xbe,
+  0xca, 0xd3, 0x2c, 0xd6, 0xec, 0x38, 0xeb, 0xe4,
+  0x53, 0xb0, 0x4c, 0x3f, 0x39, 0x29, 0xf7, 0xa4,
+  0x73, 0xa8, 0xcb, 0x32, 0x50, 0x05, 0x8c, 0x1c,
+  0x1c, 0xca, 0xc9, 0x76, 0x0b, 0x8f, 0x6b, 0x57,
+  0x1f, 0x24, 0x2b, 0xba, 0x82, 0xba, 0xed, 0x58,
+  0xd8, 0xbf, 0xec, 0x06, 0x64, 0x52, 0x6a, 0x3f,
+  0xe4, 0xad, 0xce, 0x84, 0xb4, 0x27, 0x55, 0x14,
+  0xe3, 0x75, 0x59, 0x73, 0x71, 0x51, 0xea, 0xe8,
+  0xcc, 0xda, 0x4f, 0x09, 0xaf, 0xa4, 0xbc, 0x0e,
+  0xa6, 0x1f, 0xe2, 0x3a, 0xf8, 0x96, 0x7d, 0x30,
+  0x23, 0xc5, 0x12, 0xb5, 0xd8, 0x73, 0x6b, 0x71,
+  0xab, 0xf1, 0xd7, 0x43, 0x58, 0xa7, 0xc9, 0xf0,
+  0xe4, 0x85, 0x1c, 0xd6, 0x92, 0x50, 0x2c, 0x98,
+  0x36, 0xfe, 0x87, 0xaf, 0x43, 0x8f, 0x8f, 0xf5,
+  0x88, 0x48, 0x18, 0x42, 0xcf, 0x42, 0xc1, 0xa8,
+  0xe8, 0x05, 0x08, 0xa1, 0x45, 0x70, 0x5b, 0x8c,
+  0x39, 0x28, 0xab, 0xe9, 0x6b, 0x51, 0xd2, 0xcb,
+  0x30, 0x04, 0xea, 0x7d, 0x2f, 0x6e, 0x6c, 0x3b,
+  0x5f, 0x82, 0xd9, 0x5b, 0x89, 0x37, 0x65, 0x65,
+  0xbe, 0x9f, 0xa3, 0x5d,
+};
+
+bool IsXAttrSupported(const base::FilePath& dir_path) {
+  char *path = strdup(dir_path.Append("xattr_test_XXXXXX").value().c_str());
+
+  int fd = mkstemp(path);
+  if (fd == -1) {
+    PLOG(ERROR) << "Error creating temporary file in " << dir_path.value();
+    free(path);
+    return false;
+  }
+
+  if (unlink(path) != 0) {
+    PLOG(ERROR) << "Error unlinking temporary file " << path;
+    close(fd);
+    free(path);
+    return false;
+  }
+
+  int xattr_res = fsetxattr(fd, "user.xattr-test", "value", strlen("value"), 0);
+  if (xattr_res != 0) {
+    if (errno == ENOTSUP) {
+      // Leave it to call-sites to warn about non-support.
+    } else {
+      PLOG(ERROR) << "Error setting xattr on " << path;
+    }
+  }
+  close(fd);
+  free(path);
+  return xattr_res == 0;
+}
+
+bool WriteFileVector(const string& path, const brillo::Blob& data) {
+  return utils::WriteFile(path.c_str(), data.data(), data.size());
+}
+
+bool WriteFileString(const string& path, const string& data) {
+  return utils::WriteFile(path.c_str(), data.data(), data.size());
+}
+
+// Binds provided |filename| to an unused loopback device, whose name is written
+// to the string pointed to by |lo_dev_name_p|. Returns true on success, false
+// otherwise (along with corresponding test failures), in which case the content
+// of |lo_dev_name_p| is unknown.
+bool BindToUnusedLoopDevice(const string& filename, string* lo_dev_name_p) {
+  CHECK(lo_dev_name_p);
+
+  // Bind to an unused loopback device, sanity check the device name.
+  lo_dev_name_p->clear();
+  if (!(utils::ReadPipe("losetup --show -f " + filename, lo_dev_name_p) &&
+        base::StartsWithASCII(*lo_dev_name_p, "/dev/loop", true))) {
+    ADD_FAILURE();
+    return false;
+  }
+
+  // Strip anything from the first newline char.
+  size_t newline_pos = lo_dev_name_p->find('\n');
+  if (newline_pos != string::npos)
+    lo_dev_name_p->erase(newline_pos);
+
+  return true;
+}
+
+bool ExpectVectorsEq(const brillo::Blob& expected,
+                     const brillo::Blob& actual) {
+  EXPECT_EQ(expected.size(), actual.size());
+  if (expected.size() != actual.size())
+    return false;
+  bool is_all_eq = true;
+  for (unsigned int i = 0; i < expected.size(); i++) {
+    EXPECT_EQ(expected[i], actual[i]) << "offset: " << i;
+    is_all_eq = is_all_eq && (expected[i] == actual[i]);
+  }
+  return is_all_eq;
+}
+
+void FillWithData(brillo::Blob* buffer) {
+  size_t input_counter = 0;
+  for (uint8_t& b : *buffer) {
+    b = kRandomString[input_counter];
+    input_counter++;
+    input_counter %= sizeof(kRandomString);
+  }
+}
+
+void CreateEmptyExtImageAtPath(const string& path,
+                               size_t size,
+                               int block_size) {
+  EXPECT_EQ(0, System(StringPrintf("dd if=/dev/zero of=%s"
+                                   " seek=%" PRIuS " bs=1 count=1 status=none",
+                                   path.c_str(), size)));
+  EXPECT_EQ(0, System(StringPrintf("mkfs.ext3 -q -b %d -F %s",
+                                   block_size, path.c_str())));
+}
+
+void CreateExtImageAtPath(const string& path, vector<string>* out_paths) {
+  // create 10MiB sparse file, mounted at a unique location.
+  string mount_path;
+  CHECK(utils::MakeTempDirectory(kMountPathTemplate, &mount_path));
+  ScopedDirRemover mount_path_unlinker(mount_path);
+
+  EXPECT_EQ(0, System(StringPrintf("dd if=/dev/zero of=%s"
+                                   " seek=10485759 bs=1 count=1 status=none",
+                                   path.c_str())));
+  EXPECT_EQ(0, System(StringPrintf("mkfs.ext3 -q -b 4096 -F %s",
+                                   path.c_str())));
+  EXPECT_EQ(0, System(StringPrintf("mount -o loop %s %s", path.c_str(),
+                                   mount_path.c_str())));
+  EXPECT_EQ(0, System(StringPrintf("echo hi > %s/hi", mount_path.c_str())));
+  EXPECT_EQ(0, System(StringPrintf("echo hello > %s/hello",
+                                   mount_path.c_str())));
+  EXPECT_EQ(0, System(StringPrintf("mkdir %s/some_dir", mount_path.c_str())));
+  EXPECT_EQ(0, System(StringPrintf("mkdir %s/some_dir/empty_dir",
+                                   mount_path.c_str())));
+  EXPECT_EQ(0, System(StringPrintf("mkdir %s/some_dir/mnt",
+                                   mount_path.c_str())));
+  EXPECT_EQ(0, System(StringPrintf("echo T > %s/some_dir/test",
+                                   mount_path.c_str())));
+  EXPECT_EQ(0, System(StringPrintf("mkfifo %s/some_dir/fifo",
+                                   mount_path.c_str())));
+  EXPECT_EQ(0, System(StringPrintf("mknod %s/cdev c 2 3", mount_path.c_str())));
+  EXPECT_EQ(0, System(StringPrintf("ln -s /some/target %s/sym",
+                                   mount_path.c_str())));
+  EXPECT_EQ(0, System(StringPrintf("ln %s/some_dir/test %s/testlink",
+                                   mount_path.c_str(), mount_path.c_str())));
+  EXPECT_EQ(0, System(StringPrintf("echo T > %s/srchardlink0",
+                                   mount_path.c_str())));
+  EXPECT_EQ(0, System(StringPrintf("ln %s/srchardlink0 %s/srchardlink1",
+                                   mount_path.c_str(), mount_path.c_str())));
+  EXPECT_EQ(0, System(StringPrintf("ln -s bogus %s/boguslink",
+                                   mount_path.c_str())));
+  EXPECT_TRUE(utils::UnmountFilesystem(mount_path.c_str()));
+
+  if (out_paths) {
+    out_paths->clear();
+    out_paths->push_back("");
+    out_paths->push_back("/hi");
+    out_paths->push_back("/boguslink");
+    out_paths->push_back("/hello");
+    out_paths->push_back("/some_dir");
+    out_paths->push_back("/some_dir/empty_dir");
+    out_paths->push_back("/some_dir/mnt");
+    out_paths->push_back("/some_dir/test");
+    out_paths->push_back("/some_dir/fifo");
+    out_paths->push_back("/cdev");
+    out_paths->push_back("/testlink");
+    out_paths->push_back("/sym");
+    out_paths->push_back("/srchardlink0");
+    out_paths->push_back("/srchardlink1");
+    out_paths->push_back("/lost+found");
+  }
+}
+
+ScopedLoopMounter::ScopedLoopMounter(const string& file_path,
+                                     string* mnt_path,
+                                     unsigned long flags) {  // NOLINT - long
+  EXPECT_TRUE(utils::MakeTempDirectory("mnt.XXXXXX", mnt_path));
+  dir_remover_.reset(new ScopedDirRemover(*mnt_path));
+
+  string loop_dev;
+  loop_binder_.reset(new ScopedLoopbackDeviceBinder(file_path, &loop_dev));
+
+  EXPECT_TRUE(utils::MountFilesystem(loop_dev, *mnt_path, flags));
+  unmounter_.reset(new ScopedFilesystemUnmounter(*mnt_path));
+}
+
+base::FilePath GetBuildArtifactsPath() {
+  base::FilePath exe_path;
+  base::ReadSymbolicLink(base::FilePath("/proc/self/exe"), &exe_path);
+  return exe_path.DirName();
+}
+
+}  // namespace test_utils
+}  // namespace chromeos_update_engine