WifiConnectivityManagerTest: exponential backoff periodic scan

Add a couple of unit tests to cover the periodic scan exponential
backoff feature.

Extended MockAlarmManager class such that users can query a
pending alarm's trigger time.

Bug: 28750989
Change-Id: I9520477180786fce2937e5fa87f790f60f12a3da

2 files changed, 117 insertions, 0 deletions

diff --git a/tests/wifitests/src/com/android/server/wifi/MockAlarmManager.java b/tests/wifitests/src/com/android/server/wifi/MockAlarmManager.java
index 2bb06cc30..02af28122 100644
--- a/tests/wifitests/src/com/android/server/wifi/MockAlarmManager.java
+++ b/tests/wifitests/src/com/android/server/wifi/MockAlarmManager.java
@@ -90,6 +90,20 @@ public class MockAlarmManager {
         return false;
     }
 
+    /**
+     * @return trigger time of an pending alarm with the given tag
+     *         -1 if no pending alram with the given tag
+     */
+    public long getTriggerTimeMillis(String tag) {
+        for (int i = 0; i < mPendingAlarms.size(); ++i) {
+            PendingAlarm alarm = mPendingAlarms.get(i);
+            if (Objects.equals(tag, alarm.getTag())) {
+                return alarm.getTriggerTimeMillis();
+            }
+        }
+        return -1;
+    }
+
     private static class PendingAlarm {
         private final int mType;
         private final long mTriggerAtMillis;
@@ -116,6 +130,10 @@ public class MockAlarmManager {
         public String getTag() {
             return mTag;
         }
+
+        public long getTriggerTimeMillis() {
+            return mTriggerAtMillis;
+        }
     }
 
     private class SetListenerAnswer extends AnswerWithArguments {
diff --git a/tests/wifitests/src/com/android/server/wifi/WifiConnectivityManagerTest.java b/tests/wifitests/src/com/android/server/wifi/WifiConnectivityManagerTest.java
index 872430fd8..2127a0145 100644
--- a/tests/wifitests/src/com/android/server/wifi/WifiConnectivityManagerTest.java
+++ b/tests/wifitests/src/com/android/server/wifi/WifiConnectivityManagerTest.java
@@ -102,6 +102,7 @@ public class WifiConnectivityManagerTest {
     private static final String CANDIDATE_SSID = "\"AnSsid\"";
     private static final String CANDIDATE_BSSID = "6c:f3:7f:ae:8c:f3";
     private static final String TAG = "WifiConnectivityManager Unit Test";
+    private static final long CURRENT_SYSTEM_TIME_MS = 1000;
 
     Resources mockResource() {
         Resources resource = mock(Resources.class);
@@ -519,4 +520,102 @@ public class WifiConnectivityManagerTest {
         verify(mWifiMetrics).incrementNumConnectivityWatchdogPnoGood();
         verify(mWifiMetrics, never()).incrementNumConnectivityWatchdogPnoBad();
     }
+
+    /**
+     *  Verify that scan interval for screen on and wifi disconnected scenario
+     *  is in the exponential backoff fashion.
+     *
+     * Expected behavior: WifiConnectivityManager doubles periodic
+     * scan interval.
+     */
+    @Test
+    public void checkPeriodicScanIntervalWhenDisconnected() {
+        when(mClock.currentTimeMillis()).thenReturn(CURRENT_SYSTEM_TIME_MS);
+
+        // Set screen to ON
+        mWifiConnectivityManager.handleScreenStateChanged(true);
+
+        // Set WiFi to disconnected state to trigger periodic scan
+        mWifiConnectivityManager.handleConnectionStateChanged(
+                WifiConnectivityManager.WIFI_STATE_DISCONNECTED);
+
+        // Get the first periodic scan interval
+        long firstIntervalMs = mAlarmManager
+                    .getTriggerTimeMillis(WifiConnectivityManager.PERIODIC_SCAN_TIMER_TAG)
+                    - CURRENT_SYSTEM_TIME_MS;
+        assertEquals(firstIntervalMs, WifiConnectivityManager.PERIODIC_SCAN_INTERVAL_MS);
+
+        // Now fire the first periodic scan alarm timer
+        mAlarmManager.dispatch(WifiConnectivityManager.PERIODIC_SCAN_TIMER_TAG);
+        mLooper.dispatchAll();
+
+        // Get the second periodic scan interval
+        long secondIntervalMs = mAlarmManager
+                    .getTriggerTimeMillis(WifiConnectivityManager.PERIODIC_SCAN_TIMER_TAG)
+                    - CURRENT_SYSTEM_TIME_MS;
+
+        // Verify the intervals are exponential back off
+        assertEquals(firstIntervalMs * 2, secondIntervalMs);
+
+        // Make sure we eventually stay at the maximum scan interval.
+        long intervalMs = 0;
+        for (int i = 0; i < 5; i++) {
+            mAlarmManager.dispatch(WifiConnectivityManager.PERIODIC_SCAN_TIMER_TAG);
+            mLooper.dispatchAll();
+            intervalMs = mAlarmManager
+                    .getTriggerTimeMillis(WifiConnectivityManager.PERIODIC_SCAN_TIMER_TAG)
+                    - CURRENT_SYSTEM_TIME_MS;
+        }
+
+        assertEquals(intervalMs, WifiConnectivityManager.MAX_PERIODIC_SCAN_INTERVAL_MS);
+    }
+
+    /**
+     *  Verify that scan interval for screen on and wifi connected scenario
+     *  is in the exponential backoff fashion.
+     *
+     * Expected behavior: WifiConnectivityManager doubles periodic
+     * scan interval.
+     */
+    @Test
+    public void checkPeriodicScanIntervalWhenConnected() {
+        when(mClock.currentTimeMillis()).thenReturn(CURRENT_SYSTEM_TIME_MS);
+
+        // Set screen to ON
+        mWifiConnectivityManager.handleScreenStateChanged(true);
+
+        // Set WiFi to connected state to trigger periodic scan
+        mWifiConnectivityManager.handleConnectionStateChanged(
+                WifiConnectivityManager.WIFI_STATE_CONNECTED);
+
+        // Get the first periodic scan interval
+        long firstIntervalMs = mAlarmManager
+                    .getTriggerTimeMillis(WifiConnectivityManager.PERIODIC_SCAN_TIMER_TAG)
+                    - CURRENT_SYSTEM_TIME_MS;
+        assertEquals(firstIntervalMs, WifiConnectivityManager.PERIODIC_SCAN_INTERVAL_MS);
+
+        // Now fire the first periodic scan alarm timer
+        mAlarmManager.dispatch(WifiConnectivityManager.PERIODIC_SCAN_TIMER_TAG);
+        mLooper.dispatchAll();
+
+        // Get the second periodic scan interval
+        long secondIntervalMs = mAlarmManager
+                    .getTriggerTimeMillis(WifiConnectivityManager.PERIODIC_SCAN_TIMER_TAG)
+                    - CURRENT_SYSTEM_TIME_MS;
+
+        // Verify the intervals are exponential back off
+        assertEquals(firstIntervalMs * 2, secondIntervalMs);
+
+        // Make sure we eventually stay at the maximum scan interval.
+        long intervalMs = 0;
+        for (int i = 0; i < 5; i++) {
+            mAlarmManager.dispatch(WifiConnectivityManager.PERIODIC_SCAN_TIMER_TAG);
+            mLooper.dispatchAll();
+            intervalMs = mAlarmManager
+                    .getTriggerTimeMillis(WifiConnectivityManager.PERIODIC_SCAN_TIMER_TAG)
+                    - CURRENT_SYSTEM_TIME_MS;
+        }
+
+        assertEquals(intervalMs, WifiConnectivityManager.MAX_PERIODIC_SCAN_INTERVAL_MS);
+    }
 }