diff --git a/common/fake_clock.h b/common/fake_clock.h
new file mode 100644
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--- /dev/null
+++ b/common/fake_clock.h
@@ -0,0 +1,63 @@
+//
+// Copyright (C) 2013 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.
+//
+
+#ifndef UPDATE_ENGINE_COMMON_FAKE_CLOCK_H_
+#define UPDATE_ENGINE_COMMON_FAKE_CLOCK_H_
+
+#include "update_engine/common/clock_interface.h"
+
+namespace chromeos_update_engine {
+
+// Implements a clock that can be made to tell any time you want.
+class FakeClock : public ClockInterface {
+ public:
+  FakeClock() {}
+
+  base::Time GetWallclockTime() override {
+    return wallclock_time_;
+  }
+
+  base::Time GetMonotonicTime() override {
+    return monotonic_time_;
+  }
+
+  base::Time GetBootTime() override {
+    return boot_time_;
+  }
+
+  void SetWallclockTime(const base::Time &time) {
+    wallclock_time_ = time;
+  }
+
+  void SetMonotonicTime(const base::Time &time) {
+    monotonic_time_ = time;
+  }
+
+  void SetBootTime(const base::Time &time) {
+    boot_time_ = time;
+  }
+
+ private:
+  base::Time wallclock_time_;
+  base::Time monotonic_time_;
+  base::Time boot_time_;
+
+  DISALLOW_COPY_AND_ASSIGN(FakeClock);
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_FAKE_CLOCK_H_