[chromeos] Limit the data samples stored by PowerDataCollector.

chromeos/power/power_data_collector_unittest.cc

Index: chromeos/power/power_data_collector_unittest.cc
diff --git a/chromeos/power/power_data_collector_unittest.cc b/chromeos/power/power_data_collector_unittest.cc
index a04a4d894595855868e764315c7bc2051a799005..a1a3dcc05a2e8e24a8cc8a65a024eef75c0faa64 100644
--- a/chromeos/power/power_data_collector_unittest.cc
+++ b/chromeos/power/power_data_collector_unittest.cc
@@ -38,9 +38,8 @@ TEST_F(PowerDataCollectorTest, PowerChanged) {
 
   prop1.set_external_power(power_manager::PowerSupplyProperties::DISCONNECTED);
   prop1.set_battery_percent(20.00);
-
   power_data_collector_->PowerChanged(prop1);
-  const std::vector<PowerDataCollector::PowerSupplySnapshot>& data1 =
+  const std::deque<PowerDataCollector::PowerSupplySnapshot>& data1 =
       power_data_collector_->power_supply_data();
   ASSERT_EQ(static_cast<size_t>(1), data1.size());
   EXPECT_DOUBLE_EQ(prop1.battery_percent(), data1[0].battery_percent);
@@ -48,13 +47,30 @@ TEST_F(PowerDataCollectorTest, PowerChanged) {
 
   prop2.set_external_power(power_manager::PowerSupplyProperties::AC);
   prop2.set_battery_percent(100.00);
-
   power_data_collector_->PowerChanged(prop2);
-  const std::vector<PowerDataCollector::PowerSupplySnapshot>& data2 =
+  const std::deque<PowerDataCollector::PowerSupplySnapshot>& data2 =
       power_data_collector_->power_supply_data();
   ASSERT_EQ(static_cast<size_t>(2), data2.size());
-  EXPECT_DOUBLE_EQ(prop2.battery_percent(), data1[1].battery_percent);
+  EXPECT_DOUBLE_EQ(prop2.battery_percent(), data2[1].battery_percent);

[Siva Chandra, 2014/01/10 20:27:10]

|data2| is probably not required. |data1| and |data2| hold a reference to the
same object. But it is good to keep |data2| I think. They are references to
const data.

   EXPECT_TRUE(data2[1].external_power);
 }
 
+TEST_F(PowerDataCollectorTest, AddSnapshot) {
+  PowerDataCollector::PowerSupplySnapshot snapshot1, snapshot2;
+
+  snapshot1.time = base::TimeTicks::Now();
+  snapshot2.time = base::TimeTicks::Now() + base::TimeDelta::FromSeconds(
+      PowerDataCollector::kSampleTimeLimitSec);
+
+  power_data_collector_->AddSnapshot(snapshot1);

[Daniel Erat, 2014/01/10 21:44:14]

nit: instead of making this test a friend and calling a private method, just use
the public PowerChanged() interface

[Siva Chandra, 2014/01/10 22:18:09]

PowerDataCollector::PowerChanged takes a PowerSupplyProperties arg which does
not have a time stamp. It inserts the time stamp into PowerSupplySnapshot when
recording the sample. Since we want to test eviction of old samples here, I
think we can do it either this way, or by mocking TimeTicks::Now() if we have to
test using only the public interface. Do you suggest the latter approach?

[Daniel Erat, 2014/01/10 22:28:47]

whoops, i missed that. i don't think that chrome makes it easy to mock out
::Now() (i.e. you'd need to add some set_now_for_testing() method to this class
and then use that instead of ::Now() if it's set). that's kind of a pain, so
calling AddSnapshot() from the test seems okay to me now.

+  const std::deque<PowerDataCollector::PowerSupplySnapshot>& data1 =
+      power_data_collector_->power_supply_data();
+  ASSERT_EQ(static_cast<size_t>(1), data1.size());
+
+  power_data_collector_->AddSnapshot(snapshot2);
+  const std::deque<PowerDataCollector::PowerSupplySnapshot>& data2 =
+      power_data_collector_->power_supply_data();
+  ASSERT_EQ(static_cast<size_t>(1), data2.size());
+}
+
 }  // namespace chromeos