navigator setRoot

lib/android/app/src/main/java/com/reactnativenavigation/layout/impl/ReactRootViewController.java

 
 import android.app.Activity;
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 import android.view.View;
 
 import com.facebook.react.ReactInstanceManager;
 //		}
 //	}
 
+	@NonNull
 	@Override
 	protected View createView() {
 		ReactRootView reactRootView = new ReactRootView(getActivity());

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

 	@NonNull
 	@Override
 	protected View createView() {
-		FrameLayout view = new FrameLayout(getActivity());
-		return view;
+		return new FrameLayout(getActivity());
+	}
+
+	@NonNull
+	@Override
+	public FrameLayout getView() {
+		return (FrameLayout) super.getView();
 	}
 
 	public boolean isActivityResumed() {
 	}
 
 	public void setRoot(final ViewController viewController) {
-		getActivity().setContentView(viewController.getView());
-		if (activityResumed) {
-//			viewController.onStart();
-		}
+		getView().removeAllViews();
+		getView().addView(viewController.getView());
 	}
 
 	public void onActivityCreated() {

lib/android/app/src/main/java/com/reactnativenavigation/viewcontrollers/StackController.java

 package com.reactnativenavigation.viewcontrollers;
 
 import android.app.Activity;
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.view.ViewGroup;
 import android.widget.FrameLayout;
 		}
 	}
 
+	@NonNull
 	@Override
 	public ViewGroup getView() {
 		return (ViewGroup) super.getView();
 	}
 
+	@NonNull
 	@Override
 	protected ViewGroup createView() {
 		return new FrameLayout(getActivity());

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

 import org.robolectric.Shadows;
 
 import static org.assertj.core.api.Java6Assertions.assertThat;
-import static org.mockito.Mockito.spy;
 
 public class NavigatorTest extends BaseTest {
 	private Activity activity;
 	private Navigator uut;
-	private SimpleViewController viewController;
+	private ViewController child1;
+	private ViewController child2;
 
 	@Override
 	public void beforeEach() {
 		super.beforeEach();
 		activity = newActivity();
-		viewController = spy(new SimpleViewController(activity, "simpleViewController"));
 		uut = new Navigator(activity);
+		child1 = new SimpleViewController(activity, "child1");
+		child2 = new SimpleViewController(activity, "child2");
 	}
 
 
 		uut.onActivityCreated();
 		assertThat(Shadows.shadowOf(activity).getContentView()).isNotNull().isEqualTo(uut.getView());
 	}
+
+	@Test
+	public void setRoot_AddsChildControllerView() throws Exception {
+		assertThat(uut.getView().getChildCount()).isZero();
+		uut.setRoot(child1);
+		assertHasSingleChildViewOf(child1);
+	}
+
+	@Test
+	public void setRoot_ReplacesExistingChildControllerView() throws Exception {
+		uut.setRoot(child1);
+		uut.setRoot(child2);
+		assertHasSingleChildViewOf(child2);
+	}
+
+	private void assertHasSingleChildViewOf(ViewController vc) {
+		assertThat(uut.getView().getChildCount()).isEqualTo(1);
+		assertThat(uut.getView().getChildAt(0)).isEqualTo(vc.getView()).isNotNull();
+	}
+
 }