Add registration calls for ComponentCallbacks2 (flutter/engine#34206)

engine/src/flutter/shell/platform/android/io/flutter/embedding/android/FlutterActivityAndFragmentDelegate.java

@@ -71,6 +71,11 @@ import java.util.List;
   private static final String PLUGINS_RESTORATION_BUNDLE_KEY = "plugins";
   private static final int FLUTTER_SPLASH_VIEW_FALLBACK_ID = 486947586;
 
+  /** Factory to obtain a FlutterActivityAndFragmentDelegate instance. */
+  public interface DelegateFactory {
+    FlutterActivityAndFragmentDelegate createDelegate(FlutterActivityAndFragmentDelegate.Host host);
+  }
+
   // The FlutterActivity or FlutterFragment that is delegating most of its calls
   // to this FlutterActivityAndFragmentDelegate.
   @NonNull private Host host;

engine/src/flutter/shell/platform/android/io/flutter/embedding/android/FlutterFragment.java

@@ -94,7 +94,9 @@ import java.util.List;
  * Activity}, as well as forwarding lifecycle calls from an {@code Activity} or a {@code Fragment}.
  */
 public class FlutterFragment extends Fragment
-    implements FlutterActivityAndFragmentDelegate.Host, ComponentCallbacks2 {
+    implements FlutterActivityAndFragmentDelegate.Host,
+        ComponentCallbacks2,
+        FlutterActivityAndFragmentDelegate.DelegateFactory {
   /**
    * The ID of the {@code FlutterView} created by this activity.
    *
@@ -732,6 +734,14 @@ public class FlutterFragment extends Fragment
   // implementation for details about why it exists.
   @VisibleForTesting @Nullable /* package */ FlutterActivityAndFragmentDelegate delegate;
 
+  @NonNull private FlutterActivityAndFragmentDelegate.DelegateFactory delegateFactory = this;
+
+  /** Default delegate factory that creates a simple FlutterActivityAndFragmentDelegate instance. */
+  public FlutterActivityAndFragmentDelegate createDelegate(
+      FlutterActivityAndFragmentDelegate.Host host) {
+    return new FlutterActivityAndFragmentDelegate(host);
+  }
+
   private final OnBackPressedCallback onBackPressedCallback =
       new OnBackPressedCallback(true) {
         @Override
@@ -757,8 +767,10 @@ public class FlutterFragment extends Fragment
   // TODO(mattcarroll): remove this when tests allow for it
   // (https://github.com/flutter/flutter/issues/43798)
   @VisibleForTesting
-  /* package */ void setDelegate(@NonNull FlutterActivityAndFragmentDelegate delegate) {
-    this.delegate = delegate;
+  /* package */ void setDelegateFactory(
+      @NonNull FlutterActivityAndFragmentDelegate.DelegateFactory delegateFactory) {
+    this.delegateFactory = delegateFactory;
+    delegate = delegateFactory.createDelegate(this);
   }
 
   /**
@@ -773,11 +785,12 @@ public class FlutterFragment extends Fragment
   @Override
   public void onAttach(@NonNull Context context) {
     super.onAttach(context);
-    delegate = new FlutterActivityAndFragmentDelegate(this);
+    delegate = delegateFactory.createDelegate(this);
     delegate.onAttach(context);
     if (getArguments().getBoolean(ARG_SHOULD_AUTOMATICALLY_HANDLE_ON_BACK_PRESSED, false)) {
       requireActivity().getOnBackPressedDispatcher().addCallback(this, onBackPressedCallback);
     }
+    context.registerComponentCallbacks(this);
   }
 
   @Override
@@ -873,6 +886,7 @@ public class FlutterFragment extends Fragment
 
   @Override
   public void onDetach() {
+    getContext().unregisterComponentCallbacks(this);
     super.onDetach();
     if (delegate != null) {
       delegate.onDetach();

engine/src/flutter/shell/platform/android/test/io/flutter/embedding/android/FlutterFragmentTest.java

@@ -6,9 +6,11 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.doAnswer;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
@@ -36,10 +38,25 @@ public class FlutterFragmentTest {
   private final Context ctx = ApplicationProvider.getApplicationContext();
   boolean isDelegateAttached;
 
+  class TestDelegateFactory implements FlutterActivityAndFragmentDelegate.DelegateFactory {
+    FlutterActivityAndFragmentDelegate delegate;
+
+    TestDelegateFactory(FlutterActivityAndFragmentDelegate delegate) {
+      this.delegate = delegate;
+    }
+
+    public FlutterActivityAndFragmentDelegate createDelegate(
+        FlutterActivityAndFragmentDelegate.Host host) {
+      return delegate;
+    }
+  }
+
   @Test
   public void itCreatesDefaultFragmentWithExpectedDefaults() {
     FlutterFragment fragment = FlutterFragment.createDefault();
-    fragment.setDelegate(new FlutterActivityAndFragmentDelegate(fragment));
+    TestDelegateFactory delegateFactory =
+        new TestDelegateFactory(new FlutterActivityAndFragmentDelegate(fragment));
+    fragment.setDelegateFactory(delegateFactory);
 
     assertEquals("main", fragment.getDartEntrypointFunctionName());
     assertNull(fragment.getDartEntrypointLibraryUri());
@@ -68,7 +85,9 @@ public class FlutterFragmentTest {
             .renderMode(RenderMode.texture)
             .transparencyMode(TransparencyMode.opaque)
             .build();
-    fragment.setDelegate(new FlutterActivityAndFragmentDelegate(fragment));
+    TestDelegateFactory delegateFactory =
+        new TestDelegateFactory(new FlutterActivityAndFragmentDelegate(fragment));
+    fragment.setDelegateFactory(delegateFactory);
 
     assertEquals("custom_entrypoint", fragment.getDartEntrypointFunctionName());
     assertEquals("package:foo/bar.dart", fragment.getDartEntrypointLibraryUri());
@@ -127,6 +146,7 @@ public class FlutterFragmentTest {
   public void itCanBeDetachedFromTheEngineAndStopSendingFurtherEvents() {
     FlutterActivityAndFragmentDelegate mockDelegate =
         mock(FlutterActivityAndFragmentDelegate.class);
+    TestDelegateFactory delegateFactory = new TestDelegateFactory(mockDelegate);
     FlutterFragment fragment =
         FlutterFragment.withCachedEngine("my_cached_engine")
             .destroyEngineWithFragment(true)
@@ -136,7 +156,7 @@ public class FlutterFragmentTest {
     when(mockDelegate.isAttached()).thenAnswer(invocation -> isDelegateAttached);
     doAnswer(invocation -> isDelegateAttached = false).when(mockDelegate).onDetach();
 
-    fragment.setDelegate(mockDelegate);
+    fragment.setDelegateFactory(delegateFactory);
     fragment.onStart();
     fragment.onResume();
     fragment.onPostResume();
@@ -175,13 +195,14 @@ public class FlutterFragmentTest {
     isDelegateAttached = true;
     when(mockDelegate.isAttached()).thenAnswer(invocation -> isDelegateAttached);
     doAnswer(invocation -> isDelegateAttached = false).when(mockDelegate).onDetach();
+    TestDelegateFactory delegateFactory = new TestDelegateFactory(mockDelegate);
 
     FlutterFragment fragment =
         FlutterFragment.withCachedEngine("my_cached_engine")
             .destroyEngineWithFragment(true)
             .build();
 
-    fragment.setDelegate(mockDelegate);
+    fragment.setDelegateFactory(delegateFactory);
     fragment.onStart();
     fragment.onResume();
     fragment.onPostResume();
@@ -201,13 +222,16 @@ public class FlutterFragmentTest {
     isDelegateAttached = true;
     when(mockDelegate.isAttached()).thenAnswer(invocation -> isDelegateAttached);
     doAnswer(invocation -> isDelegateAttached = false).when(mockDelegate).onDetach();
+    TestDelegateFactory delegateFactory = new TestDelegateFactory(mockDelegate);
 
     FlutterFragment fragment =
-        FlutterFragment.withCachedEngine("my_cached_engine")
-            .destroyEngineWithFragment(true)
-            .build();
+        spy(
+            FlutterFragment.withCachedEngine("my_cached_engine")
+                .destroyEngineWithFragment(true)
+                .build());
+    when(fragment.getContext()).thenReturn(mock(Context.class));
 
-    fragment.setDelegate(mockDelegate);
+    fragment.setDelegateFactory(delegateFactory);
     fragment.onStart();
     fragment.onResume();
     fragment.onPostResume();
@@ -224,7 +248,8 @@ public class FlutterFragmentTest {
   public void itReturnsExclusiveAppComponent() {
     FlutterFragment fragment = FlutterFragment.createDefault();
     FlutterActivityAndFragmentDelegate delegate = new FlutterActivityAndFragmentDelegate(fragment);
-    fragment.setDelegate(delegate);
+    TestDelegateFactory delegateFactory = new TestDelegateFactory(delegate);
+    fragment.setDelegateFactory(delegateFactory);
 
     assertEquals(fragment.getExclusiveAppComponent(), delegate);
   }
@@ -255,7 +280,8 @@ public class FlutterFragmentTest {
     isDelegateAttached = true;
     when(mockDelegate.isAttached()).thenAnswer(invocation -> isDelegateAttached);
     doAnswer(invocation -> isDelegateAttached = false).when(mockDelegate).onDetach();
-    fragment.setDelegate(mockDelegate);
+    TestDelegateFactory delegateFactory = new TestDelegateFactory(mockDelegate);
+    fragment.setDelegateFactory(delegateFactory);
 
     activity.onBackPressed();
 
@@ -294,11 +320,43 @@ public class FlutterFragmentTest {
 
     FlutterActivityAndFragmentDelegate mockDelegate =
         mock(FlutterActivityAndFragmentDelegate.class);
-    fragment.setDelegate(mockDelegate);
+    TestDelegateFactory delegateFactory = new TestDelegateFactory(mockDelegate);
+    fragment.setDelegateFactory(delegateFactory);
 
     assertTrue(fragment.popSystemNavigator());
 
     verify(mockDelegate, never()).onBackPressed();
     assertTrue(onBackPressedCalled.get());
   }
+
+  @Test
+  public void itRegistersComponentCallbacks() {
+    FlutterActivityAndFragmentDelegate mockDelegate =
+        mock(FlutterActivityAndFragmentDelegate.class);
+    isDelegateAttached = true;
+    when(mockDelegate.isAttached()).thenAnswer(invocation -> isDelegateAttached);
+    doAnswer(invocation -> isDelegateAttached = false).when(mockDelegate).onDetach();
+    TestDelegateFactory delegateFactory = new TestDelegateFactory(mockDelegate);
+
+    Context spyCtx = spy(ctx);
+    // We need to mock FlutterJNI to avoid triggering native code.
+    FlutterJNI flutterJNI = mock(FlutterJNI.class);
+    when(flutterJNI.isAttached()).thenReturn(true);
+
+    FlutterEngine flutterEngine =
+        new FlutterEngine(spyCtx, new FlutterLoader(), flutterJNI, null, false);
+    FlutterEngineCache.getInstance().put("my_cached_engine", flutterEngine);
+
+    FlutterFragment fragment = spy(FlutterFragment.withCachedEngine("my_cached_engine").build());
+    when(fragment.getContext()).thenReturn(spyCtx);
+    fragment.setDelegateFactory(delegateFactory);
+
+    fragment.onAttach(spyCtx);
+    verify(spyCtx, times(1)).registerComponentCallbacks(any());
+    verify(spyCtx, never()).unregisterComponentCallbacks(any());
+
+    fragment.onDetach();
+    verify(spyCtx, times(1)).registerComponentCallbacks(any());
+    verify(spyCtx, times(1)).unregisterComponentCallbacks(any());
+  }
 }