Simple integration test

Author: wu-hui

firebase-firestore/src/androidTest/java/com/google/firebase/firestore/FirestoreTest.java

@@ -1241,4 +1241,39 @@ public void testPendingWriteTaskResolveWhenOfflineIfThereIsNoPending() {
 
     assertTrue(awaitsPendingWrites.isComplete() && awaitsPendingWrites.isSuccessful());
   }
+
+  @Test
+  public void testGetDocumentWithMemoryLruGCEnabled() {
+    FirebaseFirestore db = testFirestore();
+    db.setFirestoreSettings(
+        new FirebaseFirestoreSettings.Builder(db.getFirestoreSettings())
+            .setPersistenceEnabled(false)
+            .setMemoryLruGcEnabled(true)
+            .build());
+
+    DocumentReference doc = db.collection("abc").document("123");
+    waitFor(doc.set(map("key", "value")));
+
+    DocumentSnapshot snapshot = waitFor(doc.get(Source.CACHE));
+    assertTrue(snapshot.exists());
+    assertTrue(snapshot.getMetadata().isFromCache());
+    assertEquals(snapshot.getData(), map("key", "value"));
+  }
+
+  @Test
+  public void testGetDocumentWithMemoryEagerGcEnabled() {
+    FirebaseFirestore db = testFirestore();
+    db.setFirestoreSettings(
+        new FirebaseFirestoreSettings.Builder(db.getFirestoreSettings())
+            .setPersistenceEnabled(false)
+            .setMemoryLruGcEnabled(false)
+            .build());
+
+    DocumentReference doc = db.collection("abc").document("123");
+    waitFor(doc.set(map("key", "value")));
+
+    Exception e = waitForException(doc.get(Source.CACHE));
+    assertTrue(e instanceof FirebaseFirestoreException);
+    assertEquals(((FirebaseFirestoreException) e).getCode(), Code.UNAVAILABLE);
+  }
 }

firebase-firestore/src/main/java/com/google/firebase/firestore/core/MemoryComponentProvider.java

@@ -67,12 +67,13 @@ protected AndroidConnectivityMonitor createConnectivityMonitor(Configuration con
 
   @Override
   protected Persistence createPersistence(Configuration configuration) {
-    if(configuration.getSettings().isMemoryLruGcEnabled()) {
+    if (configuration.getSettings().isMemoryLruGcEnabled()) {
       LocalSerializer serializer =
-        new LocalSerializer(new RemoteSerializer(configuration.getDatabaseInfo().getDatabaseId()));
+          new LocalSerializer(
+              new RemoteSerializer(configuration.getDatabaseInfo().getDatabaseId()));
       LruGarbageCollector.Params params =
-        LruGarbageCollector.Params.WithCacheSizeBytes(
-          configuration.getSettings().getCacheSizeBytes());
+          LruGarbageCollector.Params.WithCacheSizeBytes(
+              configuration.getSettings().getCacheSizeBytes());
       return MemoryPersistence.createLruGcMemoryPersistence(params, serializer);
     }