test(firestore): create FirestorePagingSourceTest

firestore/src/androidTest/java/com/firebase/ui/firestore/paging/FirestorePagingSourceTest.java

@@ -0,0 +1,124 @@
+package com.firebase.ui.firestore.paging;
+
+import com.google.android.gms.tasks.Tasks;
+import com.google.firebase.firestore.DocumentSnapshot;
+import com.google.firebase.firestore.Query;
+import com.google.firebase.firestore.QuerySnapshot;
+import com.google.firebase.firestore.Source;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import androidx.paging.PagingSource;
+import androidx.paging.PagingSource.LoadParams.Append;
+import androidx.paging.PagingSource.LoadParams.Refresh;
+import androidx.paging.PagingSource.LoadResult.Page;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyLong;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+@RunWith(AndroidJUnit4.class)
+public class FirestorePagingSourceTest {
+
+    @Mock
+    Query mMockQuery;
+
+    ArrayList<DocumentSnapshot> mMockSnapshots = new ArrayList<>();
+    Exception mMockException = new Exception("Could not load Data");
+
+    @Before
+    public void setUp() {
+        MockitoAnnotations.initMocks(this);
+        initMockQuery();
+
+        for (int i = 0; i < 2; i++) {
+            mMockSnapshots.add(mock(DocumentSnapshot.class));
+        }
+    }
+
+    @Test
+    public void testLoadInitial_success() {
+        FirestorePagingSource pagingSource = new FirestorePagingSource(mMockQuery, Source.DEFAULT);
+        mockQuerySuccess(mMockSnapshots);
+        Page<PageKey, DocumentSnapshot> expected = new Page<>(mMockSnapshots, null, new PageKey(null, null));
+
+        Refresh<PageKey> refreshRequest = new Refresh<>(null, 2, false);
+        PagingSource.LoadResult<PageKey, DocumentSnapshot> actual =
+                pagingSource.loadSingle(refreshRequest).blockingGet();
+
+        assertTrue(actual instanceof Page);
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void testLoadInitial_failure() {
+        FirestorePagingSource pagingSource = new FirestorePagingSource(mMockQuery, Source.DEFAULT);
+        mockQueryFailure(mMockException);
+        PagingSource.LoadResult.Error<PageKey, DocumentSnapshot> expected =
+                new PagingSource.LoadResult.Error<>(mMockException);
+
+        Refresh<PageKey> refreshRequest = new Refresh<>(null, 2, false);
+        PagingSource.LoadResult<PageKey, DocumentSnapshot> actual =
+                pagingSource.loadSingle(refreshRequest).blockingGet();
+
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void testLoadAfter_success() {
+        FirestorePagingSource pagingSource = new FirestorePagingSource(mMockQuery, Source.DEFAULT);
+        mockQuerySuccess(mMockSnapshots);
+        PageKey pageKey = new PageKey(null, null);
+        Page<PageKey, DocumentSnapshot> expected = new Page<>(mMockSnapshots, null, pageKey);
+
+        Append<PageKey> appendRequest = new Append<>(pageKey, 2, false);
+        PagingSource.LoadResult<PageKey, DocumentSnapshot> actual =
+                pagingSource.loadSingle(appendRequest).blockingGet();
+
+        assertTrue(actual instanceof Page);
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    public void testLoadAfter_failure() {
+        FirestorePagingSource pagingSource = new FirestorePagingSource(mMockQuery, Source.DEFAULT);
+        mockQueryFailure(mMockException);
+        PageKey pageKey = new PageKey(null, null);
+        PagingSource.LoadResult.Error<PageKey, DocumentSnapshot> expected =
+                new PagingSource.LoadResult.Error<>(mMockException);
+
+        Append<PageKey> appendRequest = new Append<>(pageKey, 2, false);
+        PagingSource.LoadResult<PageKey, DocumentSnapshot> actual =
+                pagingSource.loadSingle(appendRequest).blockingGet();
+
+        assertEquals(expected, actual);
+    }
+
+    private void initMockQuery() {
+        when(mMockQuery.startAfter(any(DocumentSnapshot.class))).thenReturn(mMockQuery);
+        when(mMockQuery.endBefore(any(DocumentSnapshot.class))).thenReturn(mMockQuery);
+        when(mMockQuery.limit(anyLong())).thenReturn(mMockQuery);
+    }
+
+    private void mockQuerySuccess(List<DocumentSnapshot> snapshots) {
+        QuerySnapshot mockSnapshot = mock(QuerySnapshot.class);
+        when(mockSnapshot.getDocuments()).thenReturn(snapshots);
+
+        when(mMockQuery.get(Source.DEFAULT)).thenReturn(Tasks.forResult(mockSnapshot));
+    }
+
+    private void mockQueryFailure(Exception exception) {
+        when(mMockQuery.get(Source.DEFAULT)).thenReturn(Tasks.forException(exception));
+    }
+}

firestore/src/main/java/com/firebase/ui/firestore/paging/PageKey.java

@@ -38,6 +38,19 @@ public Query getPageQuery(@NonNull Query baseQuery, int size) {
         return pageQuery;
     }
 
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        PageKey key = (PageKey) o;
+        if (mStartAfter == null && key.mStartAfter == null)
+            return true;
+        if (mEndBefore == null && key.mEndBefore == null)
+            return true;
+        return mStartAfter.getId() == key.mStartAfter.getId() &&
+                mEndBefore.getId() == key.mEndBefore.getId();
+    }
+
     @Override
     @NonNull
     public String toString() {