Fix dialog fragment setup, add regression test

platform/android/MapboxGLAndroidSDKTestApp/src/androidTest/java/com/mapbox/mapboxsdk/testapp/fragment/MapDialogFragmentTest.kt

@@ -0,0 +1,33 @@
+package com.mapbox.mapboxsdk.testapp.fragment
+
+import android.support.test.espresso.Espresso
+import android.support.test.espresso.Espresso.onView
+import android.support.test.espresso.action.ViewActions.click
+import android.support.test.espresso.matcher.ViewMatchers.withId
+import android.support.test.filters.LargeTest
+import android.support.test.rule.ActivityTestRule
+import android.support.test.runner.AndroidJUnit4
+import com.mapbox.mapboxsdk.testapp.R
+import com.mapbox.mapboxsdk.testapp.action.WaitAction
+import com.mapbox.mapboxsdk.testapp.activity.maplayout.MapInDialogActivity
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+/**
+ * Regression test that validates that a map inside a DialogFragment can be opened and closed.
+ */
+@RunWith(AndroidJUnit4::class)
+@LargeTest
+class MapDialogFragmentTest {
+
+    @get:Rule
+    var activityRule: ActivityTestRule<MapInDialogActivity> = ActivityTestRule(MapInDialogActivity::class.java)
+
+    @Test
+    fun openCloseDialog() {
+        onView(withId(R.id.button_open_dialog)).perform(click())
+        onView(withId(R.id.mapView)).perform(WaitAction(2500))
+        Espresso.pressBack()
+    }
+}

platform/android/MapboxGLAndroidSDKTestApp/src/main/java/com/mapbox/mapboxsdk/testapp/activity/maplayout/MapInDialogActivity.java

@@ -52,14 +52,13 @@ public static MapDialogFragment newInstance(String title) {
     }
 
     @Override
-    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
       return inflater.inflate(R.layout.fragment_dialog_map, container);
     }
 
     @Override
-    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
+    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
       super.onViewCreated(view, savedInstanceState);
-
       mapView = view.findViewById(R.id.mapView);
       mapView.onCreate(savedInstanceState);
       mapView.getMapAsync(mapboxMap -> mapboxMap.setStyle(Style.OUTDOORS));
@@ -75,6 +74,7 @@ public void dismiss() {
             mapView.onPause();
             mapView.onStop();
             mapView.onDestroy();
+            mapView = null;
           }
           super.dismiss();
         }
@@ -96,31 +96,41 @@ public void onResume() {
     @Override
     public void onPause() {
       super.onPause();
-      mapView.onPause();
+      if (mapView != null) {
+        mapView.onPause();
+      }
     }
 
     @Override
     public void onStop() {
       super.onStop();
-      mapView.onStop();
+      if (mapView != null) {
+        mapView.onStop();
+      }
     }
 
     @Override
     public void onDestroyView() {
       super.onDestroyView();
-      mapView.onDestroy();
+      if (mapView != null) {
+        mapView.onDestroy();
+      }
     }
 
     @Override
     public void onLowMemory() {
       super.onLowMemory();
-      mapView.onLowMemory();
+      if (mapView != null) {
+        mapView.onLowMemory();
+      }
     }
 
     @Override
     public void onSaveInstanceState(Bundle outState) {
       super.onSaveInstanceState(outState);
-      mapView.onSaveInstanceState(outState);
+      if (mapView != null) {
+        mapView.onSaveInstanceState(outState);
+      }
     }
   }
-}
+}