SliceLiveData should remove observers.

As positions of items will be changed, new sliceViews will be created.
SliceLiveData has been set to observe a certain old sliceView. When the
page is re-launched, we cannot garantee we always get the same
sliceView, which means the sliceLiveData may be still observing a sliveView that
is no longer applicable. This will lead to broken slices.
Hence, we need to remove observers first then make it observes a new sliceView.

Bug: 117922624
Test: robotests, visual
Change-Id: I59368a6ce5fa84487c9a4788b970fdc074a0c2a9

src/com/android/settings/homepage/slices/SliceContextualCardRenderer.java

@@ -91,14 +91,16 @@ public class SliceContextualCardRenderer implements ContextualCardRenderer,
         if (sliceLiveData == null) {
             sliceLiveData = SliceLiveData.fromUri(mContext, uri);
             mSliceLiveDataMap.put(uri.toString(), sliceLiveData);
-            sliceLiveData.observe(mLifecycleOwner, slice -> {
-                if (slice == null) {
-                    Log.w(TAG, "Slice is null");
-                }
-                cardHolder.sliceView.setSlice(slice);
-            });
         }
 
+        sliceLiveData.removeObservers(mLifecycleOwner);
+        sliceLiveData.observe(mLifecycleOwner, slice -> {
+            if (slice == null) {
+                Log.w(TAG, "Slice is null");
+            }
+            cardHolder.sliceView.setSlice(slice);
+        });
+
         // Set this listener so we can log the interaction users make on the slice
         cardHolder.sliceView.setOnSliceActionListener(this);
     }

tests/robotests/src/com/android/settings/homepage/slices/SliceContextualCardRendererTest.java

@@ -18,7 +18,7 @@ package com.android.settings.homepage.slices;
 
 import static com.google.common.truth.Truth.assertThat;
 
-import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.verify;
 
 import android.content.Context;
 import android.net.Uri;
@@ -26,8 +26,10 @@ import android.view.LayoutInflater;
 import android.view.View;
 
 import androidx.lifecycle.LifecycleOwner;
+import androidx.lifecycle.LiveData;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
+import androidx.slice.Slice;
 
 import com.android.settings.homepage.ContextualCard;
 import com.android.settings.homepage.PersonalSettingsFragment;
@@ -36,12 +38,16 @@ import com.android.settings.testutils.SettingsRobolectricTestRunner;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 import org.robolectric.RuntimeEnvironment;
 
 @RunWith(SettingsRobolectricTestRunner.class)
 public class SliceContextualCardRendererTest {
 
+    @Mock
+    private LiveData<Slice> mSliceLiveData;
+
     private Context mContext;
     private SliceContextualCardRenderer mRenderer;
     private LifecycleOwner mLifecycleOwner;
@@ -96,6 +102,16 @@ public class SliceContextualCardRendererTest {
         assertThat(mRenderer.mSliceLiveDataMap.get(sliceUri).hasObservers()).isTrue();
     }
 
+    @Test
+    public void bindview_sliceLiveDataShouldRemoveObservers() {
+        final String sliceUri = "content://com.android.settings.slices/action/flashlight";
+        mRenderer.mSliceLiveDataMap.put(sliceUri, mSliceLiveData);
+
+        mRenderer.bindView(getSliceViewHolder(), buildContextualCard(sliceUri));
+
+        verify(mSliceLiveData).removeObservers(mLifecycleOwner);
+    }
+
     private RecyclerView.ViewHolder getSliceViewHolder() {
         final int viewType = mRenderer.getViewType();
         final RecyclerView recyclerView = new RecyclerView(mContext);