First attempt at testing FavoritesActivity

app/src/androidTest/java/io/catter2/FavoritesActivityTest.java

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+package io.catter2;
+
+import android.support.test.rule.ActivityTestRule;
+import android.support.test.runner.AndroidJUnit4;
+
+import org.junit.BeforeClass;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import io.catter2.di.AppDIComponent;
+import io.catter2.di.FavoritesRepoDIModule;
+import io.catter2.di.UserDIComponent;
+import io.catter2.espresso_utils.RecyclerViewItemCountAssertion;
+import io.catter2.favorites.FavoriteModel;
+import io.catter2.favorites.FavoritesRepository;
+
+import static android.support.test.espresso.Espresso.onView;
+import static android.support.test.espresso.matcher.ViewMatchers.withId;
+
+@RunWith(AndroidJUnit4.class)
+public class FavoritesActivityTest {
+    @Rule
+    public ActivityTestRule<FavoritesActivity> activityRule =
+            new ActivityTestRule<>(FavoritesActivity.class);
+
+    @BeforeClass
+    public static void beforeClass() {
+        UserDIComponent.initialize(new FavoritesRepoDIModule() {
+            @Override
+            public AppDIComponent getAppDIComponent() {
+                return AppDIComponent.get();
+            }
+
+            @Override
+            public FavoritesRepository provideFavoritesRepository() {
+                return new FavoritesRepository() {
+                    @Override
+                    public List<FavoriteModel> getFavorites() {
+                        ArrayList<FavoriteModel> models = new ArrayList<>();
+                        models.add(new FavoriteModel(10, "url-10"));
+                        models.add(new FavoriteModel(11, "url-11"));
+                        models.add(new FavoriteModel(12, "url-12"));
+                        return models;
+                    }
+
+                    @Override
+                    public List<FavoriteModel> addFavorite(FavoriteModel model) {
+                        throw new RuntimeException("Not implemented");
+                    }
+
+                    @Override
+                    public void registerChangeListener(ChangeListener listener) {
+                        // NoOp
+                    }
+
+                    @Override
+                    public void clearChangeListener() {
+                        // NoOp
+                    }
+                };
+            }
+        });
+    }
+
+    @Test
+    public void testThereAreThreeImages() {
+        onView(withId(R.id.favorites_rv)).check(new RecyclerViewItemCountAssertion(3));
+    }
+}

app/src/androidTest/java/io/catter2/espresso_utils/RecyclerViewItemCountAssertion.java

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+package io.catter2.espresso_utils;
+
+import android.support.test.espresso.NoMatchingViewException;
+import android.support.test.espresso.ViewAssertion;
+import android.support.v7.widget.RecyclerView;
+import android.view.View;
+
+import static android.support.test.espresso.matcher.ViewMatchers.assertThat;
+import static org.hamcrest.Matchers.is;
+
+public class RecyclerViewItemCountAssertion implements ViewAssertion {
+    private final int expectedCount;
+
+    public RecyclerViewItemCountAssertion(int expectedCount) {
+        this.expectedCount = expectedCount;
+    }
+
+    @Override
+    public void check(View view, NoMatchingViewException noViewFoundException) {
+        if (noViewFoundException != null) {
+            throw noViewFoundException;
+        }
+
+        RecyclerView recyclerView = (RecyclerView) view;
+        RecyclerView.Adapter adapter = recyclerView.getAdapter();
+        assertThat(adapter.getItemCount(), is(expectedCount));
+    }
+}