constructViewTest: create ReactHostImpl directly (bridgeless)

android/app/src/androidTest/java/com/testapp/IsolatedTest.kt

@@ -1,50 +1,104 @@
 package com.rnstorybookautoscreenshots
 
+import android.app.Application
+import android.graphics.Color
+import android.view.View
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import androidx.test.platform.app.InstrumentationRegistry
-import com.testapp.MainApplication
+import com.facebook.react.PackageList
+import com.facebook.react.common.annotations.UnstableReactNativeAPI
+import com.facebook.react.bridge.JSBundleLoader
+import com.facebook.react.defaults.DefaultComponentsRegistry
+import com.facebook.react.defaults.DefaultReactHostDelegate
+import com.facebook.react.defaults.DefaultTurboModuleManagerDelegate
+import com.facebook.react.fabric.ComponentFactory
+import com.facebook.react.runtime.ReactHostImpl
+import com.facebook.react.runtime.hermes.HermesInstance
 import junit.framework.TestCase.assertNotNull
 import junit.framework.TestCase.assertTrue
 import org.junit.Test
 import org.junit.runner.RunWith
-import com.facebook.testing.screenshot.ViewHelpers
 import com.facebook.testing.screenshot.Screenshot
+import com.facebook.testing.screenshot.ViewHelpers
+import com.facebook.testing.screenshot.WindowAttachment
 import org.junit.Assert.*;
 import com.facebook.react.interfaces.*
 
 @RunWith(AndroidJUnit4::class)
 class IsolatedTest {
+
     @Test
     fun simpleTest() {
         assertTrue(true)
     }
 
+    @OptIn(UnstableReactNativeAPI::class)
     @Test
     fun constructViewTest() {
-        val context = InstrumentationRegistry.getInstrumentation().targetContext
-        val app = context.applicationContext as MainApplication
-        val surface = app.reactHost.createSurface(context, "SimpleTestComponent", null)
-        assertEquals("SimpleTestComponent", surface.moduleName)
-
-        // TODO: we aren't 100% sure if prerender() and start() are being called the way we want it to.
-        // We probably want to create a ReactHost directly instead of taking it from the MainApplication... probably
-        // Also look up bridge-less mode.
-        assertGoodTask(surface.prerender())
+        val instrumentation = InstrumentationRegistry.getInstrumentation()
+        val context = instrumentation.targetContext
+        val app = context.applicationContext as Application
 
+        val bundleLoader = JSBundleLoader.createAssetLoader(
+            context, "assets://index.android.bundle", true)
+        val delegate = DefaultReactHostDelegate(
+            jsMainModulePath = "index",
+            jsBundleLoader = bundleLoader,
+            reactPackages = PackageList(app).packages,
+            jsRuntimeFactory = HermesInstance(),
+            turboModuleManagerDelegateBuilder = DefaultTurboModuleManagerDelegate.Builder(),
+            exceptionHandler = { throw it },
+        )
+        val componentFactory = ComponentFactory()
+        DefaultComponentsRegistry.register(componentFactory)
+        val reactHost = ReactHostImpl(
+            context,
+            delegate,
+            componentFactory,
+            false, // allowPackagerServerAccess
+            false, // useDevSupport
+        )
 
+        val surface = reactHost.createSurface(context, "SimpleTestComponent", null)
+        assertEquals("SimpleTestComponent", surface.moduleName)
         assertNotNull(surface.view)
 
-        ViewHelpers.setupView(surface.view!!)
-            .setExactHeightPx(1000)
-            .setExactWidthPx(1000)
-            .layout()
+        val view = surface.view!!
+
+        var detacher: WindowAttachment.Detacher? = null
+        var startTask: com.facebook.react.interfaces.TaskInterface<Void>? = null
+
+        try {
+            instrumentation.runOnMainSync {
+                reactHost.onHostResume(null)
+                view.setLayerType(View.LAYER_TYPE_SOFTWARE, null)
+                view.setBackgroundColor(Color.WHITE)
+                detacher = WindowAttachment.dispatchAttach(view)
+                ViewHelpers.setupView(view).setExactWidthPx(1080).setExactHeightPx(1920).layout()
+                startTask = surface.start()
+            }
 
+            // Wait for the surface start task to complete off the main thread.
+            assertGoodTask(startTask!!)
 
-        val ti = surface.start()
-        assertGoodTask(ti)
+            // Poll until Fabric has mounted child views into the surface.
+            val deadline = System.currentTimeMillis() + 30_000
+            var hasChildren = false
+            while (!hasChildren && System.currentTimeMillis() < deadline) {
+                Thread.sleep(50)
+                instrumentation.runOnMainSync { hasChildren = view.childCount > 0 }
+            }
+            assertTrue("Timed out waiting for React Native to render content", hasChildren)
 
-        Screenshot.snap(surface.view!!)
-            .record()
+            instrumentation.runOnMainSync {
+                Screenshot.snap(view).setName("SimpleTestComponent").record()
+            }
+        } finally {
+            instrumentation.runOnMainSync {
+                surface.stop()
+                detacher?.detach()
+            }
+        }
     }
 }