add test

Author: milaGGL

google-cloud-firestore/src/main/java/com/google/cloud/firestore/Order.java

@@ -135,13 +135,19 @@ public int compare(@Nonnull Value left, @Nonnull Value right) {
   }
 
   private int compareStrings(Value left, Value right) {
-    return left.getStringValue().compareTo(right.getStringValue());
+    ByteString leftBytes = ByteString.copyFromUtf8(left.getStringValue());
+    ByteString rightBytes = ByteString.copyFromUtf8(right.getStringValue());
+//    return left.getStringValue().compareTo(right.getStringValue());
+    return compareBytes(leftBytes, rightBytes);
   }
 
   private int compareBlobs(Value left, Value right) {
     ByteString leftBytes = left.getBytesValue();
     ByteString rightBytes = right.getBytesValue();
+    return compareBytes(leftBytes, rightBytes);
+  }
 
+  private int compareBytes(ByteString leftBytes, ByteString rightBytes){
     int size = Math.min(leftBytes.size(), rightBytes.size());
     for (int i = 0; i < size; i++) {
       // Make sure the bytes are unsigned

google-cloud-firestore/src/test/java/com/google/cloud/firestore/it/ITQueryTest.java

@@ -34,6 +34,8 @@
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.CountDownLatch;
+import  java.util.ArrayList;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
@@ -1113,4 +1115,45 @@ public void testAggregateQueryProfile() throws Exception {
     assertThat(stats.getResultsReturned()).isEqualTo(1);
     assertThat(stats.getExecutionDuration()).isGreaterThan(Duration.ZERO);
   }
+
+  @Test
+  public void snapshotListenerSortsUnicodesSameWayAsServer() throws Exception {
+    CollectionReference col = createEmptyCollection();
+
+    firestore
+            .batch()
+            .set(col.document("a"), map("value", "Łukasiewicz"))
+            .set(col.document("b"), map("value", "Sierpiński"))
+            .set(col.document("c"), map("value", "岩澤"))
+            .set(col.document("d"), map("value", "🄟"))
+            .set(col.document("e"), map("value", "Ｐ"))
+            .set(col.document("f"), map("value", "︒"))
+            .set(col.document("g"), map("value", "🐵"))
+
+            .commit()
+            .get();
+
+    Query query = col.orderBy("value", Direction.ASCENDING);
+
+    QuerySnapshot snapshot = query.get().get();
+    List<String> queryOrder =
+            snapshot.getDocuments().stream().map(doc -> doc.getId()).collect(Collectors.toList());
+
+    CountDownLatch latch = new CountDownLatch(1);
+    List<String> listenerOrder = new ArrayList<>();
+    ListenerRegistration registration =
+            query.addSnapshotListener(
+                    (value, error) -> {
+                      listenerOrder.addAll(
+                              value.getDocuments().stream()
+                                      .map(doc -> doc.getId())
+                                      .collect(Collectors.toList()));
+                      latch.countDown();
+                    });
+    latch.await();
+    registration.remove();
+
+    assertEquals(queryOrder, Arrays.asList("b", "a", "c", "f", "e", "d", "g"));
+    assertEquals(queryOrder, listenerOrder); // Assert order in the SDK
+  }
 }