Fix DevMenuMainViewInstrumentationTest

Author: mattcreaser

core/src/androidTest/java/com/amplifyframework/devmenu/DevMenuMainViewInstrumentationTest.java

@@ -29,6 +29,8 @@
 import org.junit.Before;
 import org.junit.Test;
 
+import java.util.concurrent.CountDownLatch;
+
 import static androidx.test.espresso.Espresso.onView;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
@@ -38,20 +40,24 @@
  */
 public final class DevMenuMainViewInstrumentationTest {
     // A navigation host controller for testing.
-    private TestNavHostController navHostController;
+    private volatile TestNavHostController navHostController;
 
     /**
      * Go to the main screen of the developer menu.
+     * @throws Exception if fragment doesn't attach
      */
     @Before
-    public void resetView() {
+    public void resetView() throws Exception {
+        CountDownLatch latch = new CountDownLatch(1);
         FragmentScenario<DevMenuMainFragment> mainMenuScenario =
                 FragmentScenario.launchInContainer(DevMenuMainFragment.class);
         mainMenuScenario.onFragment(fragment -> {
             navHostController = new TestNavHostController(ApplicationProvider.getApplicationContext());
             navHostController.setGraph(R.navigation.dev_menu_nav_graph);
             Navigation.setViewNavController(fragment.requireView(), navHostController);
+            latch.countDown();
         });
+        latch.await();
     }