Add unit tests for duration metrics
As a side-effect, move utils::GetMonotonicTime() into the newly added
ClockInterface type.
BUG=None
TEST=Unit tests pass
Change-Id: I972a7e4ba37b63f96348fbeda901697b8ba2fc05
Reviewed-on: https://gerrit.chromium.org/gerrit/48814
Reviewed-by: Chris Sosa <sosa@chromium.org>
Tested-by: David Zeuthen <zeuthen@chromium.org>
Commit-Queue: David Zeuthen <zeuthen@chromium.org>
diff --git a/clock_interface.h b/clock_interface.h
new file mode 100644
index 0000000..c2b1a04
--- /dev/null
+++ b/clock_interface.h
@@ -0,0 +1,35 @@
+// Copyright (c) 2013 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.
+
+#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_CLOCK_INTERFACE_H__
+#define CHROMEOS_PLATFORM_UPDATE_ENGINE_CLOCK_INTERFACE_H__
+
+#include <string>
+
+#include <base/time.h>
+
+namespace chromeos_update_engine {
+
+// The clock interface allows access to various system clocks. The
+// sole reason for providing this as an interface is unit testing.
+// Additionally, the sole reason for the methods not being static
+// is also unit testing.
+class ClockInterface {
+ public:
+ // Gets the current time e.g. similar to base::Time::Now().
+ virtual base::Time GetWallclockTime() = 0;
+
+ // Returns monotonic time since some unspecified starting point. It
+ // is not increased when the system is sleeping nor is it affected
+ // by NTP or the user changing the time.
+ //
+ // (This is a simple wrapper around clock_gettime(2) / CLOCK_MONOTONIC_RAW.)
+ virtual base::Time GetMonotonicTime() = 0;
+
+ virtual ~ClockInterface() {}
+};
+
+} // namespace chromeos_update_engine
+
+#endif // CHROMEOS_PLATFORM_UPDATE_ENGINE_CLOCK_INTERFACE_H__