diff --git a/hwid_override_unittest.cc b/hwid_override_unittest.cc
new file mode 100644
index 0000000..01c9fa0
--- /dev/null
+++ b/hwid_override_unittest.cc
@@ -0,0 +1,55 @@
+// Copyright (c) 2012 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 "update_engine/hwid_override.h"
+
+#include <string>
+
+#include <base/file_path.h>
+#include <base/file_util.h>
+#include <base/files/scoped_temp_dir.h>
+#include <gtest/gtest.h>
+
+namespace chromeos_update_engine {
+
+class HwidOverrideTest : public ::testing::Test {
+ public:
+  HwidOverrideTest() {}
+  virtual ~HwidOverrideTest() {}
+
+  virtual void SetUp() {
+    ASSERT_TRUE(tempdir_.CreateUniqueTempDir());
+    ASSERT_TRUE(file_util::CreateDirectory(tempdir_.path().Append("etc")));
+  }
+
+ protected:
+  base::ScopedTempDir tempdir_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(HwidOverrideTest);
+};
+
+TEST_F(HwidOverrideTest, ReadGood) {
+  std::string expected_hwid("expected");
+  std::string keyval(HwidOverride::kHwidOverrideKey);
+  keyval += ("=" + expected_hwid);
+  ASSERT_EQ(file_util::WriteFile(tempdir_.path().Append("etc/lsb-release"),
+                                 keyval.c_str(), keyval.length()),
+            keyval.length());
+  EXPECT_EQ(expected_hwid, HwidOverride::Read(tempdir_.path()));
+}
+
+TEST_F(HwidOverrideTest, ReadNothing) {
+  std::string keyval("SOMETHING_ELSE=UNINTERESTING");
+  ASSERT_EQ(file_util::WriteFile(tempdir_.path().Append("etc/lsb-release"),
+                                 keyval.c_str(), keyval.length()),
+            keyval.length());
+  EXPECT_EQ(std::string(), HwidOverride::Read(tempdir_.path()));
+}
+
+TEST_F(HwidOverrideTest, ReadFailure) {
+  EXPECT_EQ(std::string(), HwidOverride::Read(tempdir_.path()));
+}
+
+}  // namespace chromeos_update_engine