Merge "Always report non-null TetherStatesParcel"

Tethering/src/com/android/server/connectivity/tethering/Tethering.java

@@ -1944,7 +1944,8 @@ public class Tethering {
             parcel.tetheringSupported = mDeps.isTetheringSupported();
             parcel.upstreamNetwork = mTetherUpstream;
             parcel.config = mConfig.toStableParcelable();
-            parcel.states = mTetherStatesParcel;
+            parcel.states =
+                    mTetherStatesParcel != null ? mTetherStatesParcel : emptyTetherStatesParcel();
             try {
                 callback.onCallbackStarted(parcel);
             } catch (RemoteException e) {
@@ -1953,6 +1954,17 @@ public class Tethering {
         });
     }
 
+    private TetherStatesParcel emptyTetherStatesParcel() {
+        final TetherStatesParcel parcel = new TetherStatesParcel();
+        parcel.availableList = new String[0];
+        parcel.tetheredList = new String[0];
+        parcel.localOnlyList = new String[0];
+        parcel.erroredIfaceList = new String[0];
+        parcel.lastErrorList = new int[0];
+
+        return parcel;
+    }
+
     /** Unregister tethering event callback */
     void unregisterTetheringEventCallback(ITetheringEventCallback callback) {
         mHandler.post(() -> {

Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringTest.java

@@ -127,6 +127,7 @@ import com.android.internal.util.StateMachine;
 import com.android.internal.util.test.BroadcastInterceptingContext;
 import com.android.internal.util.test.FakeSettingsProvider;
 import com.android.networkstack.tethering.R;
+import com.android.testutils.MiscAssertsKt;
 
 import org.junit.After;
 import org.junit.Before;
@@ -1220,6 +1221,16 @@ public class TetheringTest {
         }
     }
 
+    private void assertTetherStatesNotNullButEmpty(final TetherStatesParcel parcel) {
+        assertFalse(parcel == null);
+        assertEquals(0, parcel.availableList.length);
+        assertEquals(0, parcel.tetheredList.length);
+        assertEquals(0, parcel.localOnlyList.length);
+        assertEquals(0, parcel.erroredIfaceList.length);
+        assertEquals(0, parcel.lastErrorList.length);
+        MiscAssertsKt.assertFieldCountEquals(5, TetherStatesParcel.class);
+    }
+
     @Test
     public void testRegisterTetheringEventCallback() throws Exception {
         TestTetheringEventCallback callback = new TestTetheringEventCallback();
@@ -1232,7 +1243,7 @@ public class TetheringTest {
         callback.expectConfigurationChanged(
                 mTethering.getTetheringConfiguration().toStableParcelable());
         TetherStatesParcel tetherState = callback.pollTetherStatesChanged();
-        assertEquals(tetherState, null);
+        assertTetherStatesNotNullButEmpty(tetherState);
         // 2. Enable wifi tethering.
         UpstreamNetworkState upstreamState = buildMobileDualStackUpstreamState();
         when(mUpstreamNetworkMonitor.getCurrentPreferredUpstream()).thenReturn(upstreamState);