Fix potential NPE in WifiService dump

Added nullchecks to WifiServiceImpl & WifiMetrics dump methods usage of
args.
This is a precaution to similar null pointer exceptions that were occuring in
statemachine dump methods.

Bug: 37907061
Test: Added some unit tests
Change-Id: I0ab74421cddc31f7270cdd314fb86678194be0f0

2 files changed, 19 insertions, 0 deletions

diff --git a/tests/wifitests/src/com/android/server/wifi/WifiMetricsTest.java b/tests/wifitests/src/com/android/server/wifi/WifiMetricsTest.java
index 22744b63b..4d9c906ea 100644
--- a/tests/wifitests/src/com/android/server/wifi/WifiMetricsTest.java
+++ b/tests/wifitests/src/com/android/server/wifi/WifiMetricsTest.java
@@ -41,7 +41,9 @@ import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
 import java.io.ByteArrayOutputStream;
+import java.io.FileDescriptor;
 import java.io.PrintWriter;
+import java.io.StringWriter;
 import java.util.ArrayList;
 import java.util.BitSet;
 import java.util.List;
@@ -1006,6 +1008,15 @@ public class WifiMetricsTest {
         dumpProtoAndDeserialize();
         assertEquals(WifiMetrics.MAX_STA_EVENTS, mDeserializedWifiMetrics.staEventList.length);
     }
+
+    /**
+     * Ensure WifiMetrics doesn't cause a null pointer exception when called with null args
+     */
+    @Test
+    public void testDumpNullArg() {
+        mWifiMetrics.dump(new FileDescriptor(), new PrintWriter(new StringWriter()), null);
+    }
+
     /**
      * Generate an RSSI delta event by creating a connection event and an RSSI poll within
      * 'interArrivalTime' milliseconds of each other.
diff --git a/tests/wifitests/src/com/android/server/wifi/WifiServiceImplTest.java b/tests/wifitests/src/com/android/server/wifi/WifiServiceImplTest.java
index b1f035450..c81970d54 100644
--- a/tests/wifitests/src/com/android/server/wifi/WifiServiceImplTest.java
+++ b/tests/wifitests/src/com/android/server/wifi/WifiServiceImplTest.java
@@ -276,6 +276,14 @@ public class WifiServiceImplTest {
 
 
     /**
+     * Ensure WifiServiceImpl.dump() doesn't throw an NPE when executed with null args
+     */
+    @Test
+    public void testDumpNullArgs() {
+        mWifiServiceImpl.dump(new FileDescriptor(), new PrintWriter(new StringWriter()), null);
+    }
+
+    /**
      * Verify that wifi can be enabled by a caller with WIFI_STATE_CHANGE permission when wifi is
      * off (no hotspot, no airplane mode).
      */