Defer activity results through ReactHost tasks

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/runtime/ReactHostImpl.kt

@@ -660,11 +660,10 @@ public class ReactHostImpl(
     val method =
         "onActivityResult(activity = \"$activity\", requestCode = \"$requestCode\", resultCode = \"$resultCode\", data = \"$data\")"
 
-    val currentContext = currentReactContext
-    if (currentContext != null) {
-      currentContext.onActivityResult(activity, requestCode, resultCode, data)
-    } else {
-      raiseSoftException(method, "Tried to access onActivityResult while context is not ready")
+    callWithExistingReactContext(method) { reactContext ->
+      if (!activity.isDestroyed) {
+        reactContext.onActivityResult(activity, requestCode, resultCode, data)
+      }
     }
   }
 
@@ -930,6 +929,32 @@ public class ReactHostImpl(
               executor,
           )
 
+  /** Schedule UI work after an already requested ReactInstance has finished initializing. */
+  private fun callWithExistingReactContext(
+      callingMethod: String,
+      runnable: (reactContext: ReactContext) -> Unit,
+  ): Task<Boolean> =
+      // Read the task on the host executor, after any previously scheduled start work.
+      Task.call({ createReactInstanceTaskRef.get() }, bgExecutor)
+          .onSuccess(
+              { instanceTask ->
+                val reactContext = currentReactContext
+                if (instanceTask.getResult() == null || reactContext == null) {
+                  raiseSoftException(
+                      "callWithExistingReactContext($callingMethod)",
+                      "Execute: ReactContext is null. Dropping work.",
+                  )
+                  false
+                } else if (instanceTask.getResult() !== reactInstance) {
+                  false
+                } else {
+                  runnable(reactContext)
+                  true
+                }
+              },
+              uiExecutor,
+          )
+
   /** Create a ReactInstance if it doesn't exist already, and schedule work on it. */
   private fun callAfterGetOrCreateReactInstance(
       callingMethod: String,

packages/react-native/ReactAndroid/src/test/java/com/facebook/react/runtime/ReactHostTest.kt

@@ -8,6 +8,7 @@
 package com.facebook.react.runtime
 
 import android.app.Activity
+import android.content.Intent
 import com.facebook.react.MemoryPressureRouter
 import com.facebook.react.bridge.UIManager
 import com.facebook.react.common.LifecycleState
@@ -31,6 +32,7 @@ import org.mockito.kotlin.any
 import org.mockito.kotlin.doNothing
 import org.mockito.kotlin.doReturn
 import org.mockito.kotlin.mock
+import org.mockito.kotlin.never
 import org.mockito.kotlin.spy
 import org.mockito.kotlin.verify
 import org.mockito.kotlin.whenever
@@ -143,6 +145,89 @@ class ReactHostTest {
     assertThat(reactHost.currentReactContext).isNull()
   }
 
+  @Test
+  fun testActivityResultWithInitializedContext() {
+    reactHost.start()
+    val intent = Intent("test-result")
+
+    reactHost.onActivityResult(activityController.get(), 7, Activity.RESULT_OK, intent)
+
+    verify(checkNotNull(reactHost.currentReactContext))
+        .onActivityResult(activityController.get(), 7, Activity.RESULT_OK, intent)
+  }
+
+  @Test
+  fun testActivityResultsWaitForScheduledInitialization() {
+    val bgTasks = ArrayDeque<Runnable>()
+    reactHost =
+        spy(
+            ReactHostImpl(
+                activityController.get().application,
+                reactHostDelegate,
+                mock(),
+                { bgTasks.add(it) },
+                Task.IMMEDIATE_EXECUTOR,
+                false /* allowPackagerServerAccess */,
+                false /* useDevSupport */,
+            ),
+        )
+    doReturn(null).whenever(reactHost).getOrCreateReactHostInspectorTarget()
+    doNothing().whenever(reactHost).unregisterInstanceFromInspector(any())
+
+    reactHost.start()
+    val intent = Intent("test-result")
+    reactHost.onActivityResult(activityController.get(), 7, Activity.RESULT_OK, intent)
+    reactHost.onActivityResult(activityController.get(), 8, Activity.RESULT_CANCELED, null)
+    assertThat(reactHost.currentReactContext).isNull()
+
+    while (bgTasks.isNotEmpty()) bgTasks.removeFirst().run()
+
+    val reactContext = checkNotNull(reactHost.currentReactContext)
+    val ordered = org.mockito.Mockito.inOrder(reactContext)
+    ordered
+        .verify(reactContext)
+        .onActivityResult(activityController.get(), 7, Activity.RESULT_OK, intent)
+    ordered
+        .verify(reactContext)
+        .onActivityResult(activityController.get(), 8, Activity.RESULT_CANCELED, null)
+  }
+
+  @Test
+  fun testActivityResultDoesNotStartAnUnusedHost() {
+    reactHost.onActivityResult(activityController.get(), 7, Activity.RESULT_OK, null)
+
+    assertThat(reactHost.currentReactContext).isNull()
+    assertThat(mockedReactInstanceCtor.constructed()).isEmpty()
+  }
+
+  @Test
+  fun testActivityResultIsNotDeliveredToDestroyedActivity() {
+    val bgTasks = ArrayDeque<Runnable>()
+    reactHost =
+        spy(
+            ReactHostImpl(
+                activityController.get().application,
+                reactHostDelegate,
+                mock(),
+                { bgTasks.add(it) },
+                Task.IMMEDIATE_EXECUTOR,
+                false /* allowPackagerServerAccess */,
+                false /* useDevSupport */,
+            ),
+        )
+    doReturn(null).whenever(reactHost).getOrCreateReactHostInspectorTarget()
+    doNothing().whenever(reactHost).unregisterInstanceFromInspector(any())
+
+    val activity = activityController.get()
+    reactHost.start()
+    reactHost.onActivityResult(activity, 7, Activity.RESULT_OK, null)
+    activityController.pause().stop().destroy()
+    while (bgTasks.isNotEmpty()) bgTasks.removeFirst().run()
+
+    verify(checkNotNull(reactHost.currentReactContext), never())
+        .onActivityResult(activity, 7, Activity.RESULT_OK, null)
+  }
+
   @Test
   fun testReload() {
     reactHost.start()