Fix setRoot wait for render (#5309)

Fix white screen after calling setRoot() before rendering. Fix #5308

lib/android/app/src/main/java/com/reactnativenavigation/viewcontrollers/navigator/Navigator.java

@@ -33,6 +33,7 @@ public class Navigator extends ParentController {
     private final OverlayManager overlayManager;
     private final RootPresenter rootPresenter;
     private ViewController root;
+    private ViewController previousRoot;
     private final FrameLayout rootLayout;
     private final FrameLayout modalsLayout;
     private final FrameLayout overlaysLayout;
@@ -122,13 +123,18 @@ public class Navigator extends ParentController {
         root = null;
     }
 
+    private void destroyPreviousRoot() {
+        if (previousRoot != null) previousRoot.destroy();
+        previousRoot = null;
+    }
+
     @Override
     public void sendOnNavigationButtonPressed(String buttonId) {
 
     }
 
     public void setRoot(final ViewController viewController, CommandListener commandListener, ReactInstanceManager reactInstanceManager) {
-        destroyRoot();
+        previousRoot = root;
         modalStack.destroy();
         final boolean removeSplashView = isRootNotCreated();
         if (isRootNotCreated()) getView();
@@ -138,6 +144,7 @@ public class Navigator extends ParentController {
             public void onSuccess(String childId) {
                 if (removeSplashView) removePreviousContentView();
                 super.onSuccess(childId);
+                destroyPreviousRoot();
             }
 
             private void removePreviousContentView() {

lib/android/app/src/test/java/com/reactnativenavigation/viewcontrollers/navigator/NavigatorTest.java

@@ -53,6 +53,7 @@ import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyZeroInteractions;
 import static org.mockito.Mockito.when;
 
 @Config(qualifiers = "xxhdpi")
@@ -167,6 +168,20 @@ public class NavigatorTest extends BaseTest {
         assertIsChild(uut.getRootLayout(), child2.getView());
     }
 
+    @Test
+    public void setRoot_WithWaitForRender() {
+        ViewController primaryView = spy(child2);
+        uut.setRoot(primaryView, new CommandListenerAdapter(), reactInstanceManager);
+        child3.options.animations.setRoot.waitForRender = new Bool(true);
+        ViewController secondaryView = spy(child3);
+        CommandListenerAdapter listener = spy(new CommandListenerAdapter());
+        uut.setRoot(secondaryView, listener, reactInstanceManager);
+        verify(secondaryView).addOnAppearedListener(any());
+        verifyZeroInteractions(listener);
+        assertThat(primaryView.isViewShown()).isEqualTo(true);
+        secondaryView.onViewAppeared();
+    }
+
     @Test
     public void setRoot_destroysModals() {
         uut.showModal(child1, new CommandListenerAdapter());