test: screenshot plain Android view in IsolatedTest

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

@@ -1,15 +1,34 @@
 package com.rnstorybookautoscreenshots
 
+import android.Manifest
+import android.graphics.PixelFormat
+import android.os.Handler
+import android.os.Looper
+import android.view.Choreographer
+import android.view.ContextThemeWrapper
+import android.view.View
+import android.view.ViewGroup
+import android.view.WindowManager
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.rule.GrantPermissionRule
+import com.facebook.testing.screenshot.Screenshot
 import com.testapp.MainApplication
 import junit.framework.TestCase.assertNotNull
 import junit.framework.TestCase.assertTrue
+import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
+import java.util.concurrent.CountDownLatch
 
 @RunWith(AndroidJUnit4::class)
 class IsolatedTest {
+
+    @get:Rule
+    val permissionRule: GrantPermissionRule = GrantPermissionRule.grant(
+        Manifest.permission.SYSTEM_ALERT_WINDOW
+    )
+
     @Test
     fun simpleTest() {
         assertTrue(true)
@@ -23,4 +42,71 @@ class IsolatedTest {
         surface.start()
         assertNotNull(surface.view)
     }
+
+    @Test
+    fun screenshotSimpleTestComponent() {
+        val instrumentation = InstrumentationRegistry.getInstrumentation()
+        val context = instrumentation.targetContext
+        val app = context.applicationContext as MainApplication
+
+        val themedContext = ContextThemeWrapper(context, context.applicationInfo.theme)
+        val surface = app.reactHost.createSurface(themedContext, "SimpleTestComponent", null)
+        val view = surface.view
+            ?: throw IllegalStateException("ReactSurface returned a null view")
+
+        val wm = context.getSystemService(android.content.Context.WINDOW_SERVICE) as WindowManager
+        val params = WindowManager.LayoutParams(
+            1080,
+            1920,
+            WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY,
+            WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
+            PixelFormat.TRANSLUCENT
+        ).apply { alpha = 0f }
+
+        instrumentation.runOnMainSync {
+            view.setLayerType(View.LAYER_TYPE_SOFTWARE, null)
+            wm.addView(view, params)
+            surface.start()
+        }
+
+        // Wait for JS to load and Fabric to mount children (up to 30s for cold start)
+        val deadline = System.currentTimeMillis() + 30_000L
+        while (System.currentTimeMillis() < deadline) {
+            waitTwoFrames()
+            var childCount = 0
+            instrumentation.runOnMainSync { childCount = view.childCount }
+            if (childCount > 0) break
+        }
+
+        instrumentation.runOnMainSync {
+            // Child views added by Fabric default to hardware acceleration;
+            // set software layer recursively so Screenshot.snap() can capture them.
+            setLayerTypeSoftwareRecursively(view)
+            Screenshot.snap(view).setName("simple_test_component").record()
+        }
+
+        instrumentation.runOnMainSync {
+            surface.stop()
+            wm.removeView(view)
+        }
+    }
+
+    private fun setLayerTypeSoftwareRecursively(view: View) {
+        view.setLayerType(View.LAYER_TYPE_SOFTWARE, null)
+        if (view is ViewGroup) {
+            for (i in 0 until view.childCount) {
+                setLayerTypeSoftwareRecursively(view.getChildAt(i))
+            }
+        }
+    }
+
+    private fun waitTwoFrames() {
+        repeat(2) {
+            val latch = CountDownLatch(1)
+            Handler(Looper.getMainLooper()).post {
+                Choreographer.getInstance().postFrameCallback { latch.countDown() }
+            }
+            latch.await()
+        }
+    }
 }