add test

dev/src/order.ts

@@ -248,6 +248,16 @@ function compareVectors(left: ApiMapValue, right: ApiMapValue): number {
   return compareArrays(leftArray, rightArray);
 }
 
+function stringToUTF8Bytes(str: string): Uint8Array {
+  return new TextEncoder().encode(str);
+}
+
+function compareUTF8bytes(left: string, right: string): number {
+  const leftBytes = stringToUTF8Bytes(left);
+  const rightBytes = stringToUTF8Bytes(right);
+  return Buffer.compare(Buffer.from(leftBytes), Buffer.from(rightBytes));
+}
+
 /*!
  * @private
  * @internal
@@ -269,7 +279,7 @@ export function compare(left: api.IValue, right: api.IValue): number {
     case TypeOrder.BOOLEAN:
       return primitiveComparator(left.booleanValue!, right.booleanValue!);
     case TypeOrder.STRING:
-      return primitiveComparator(left.stringValue!, right.stringValue!);
+      return compareUTF8bytes(left.stringValue!, right.stringValue!);
     case TypeOrder.NUMBER:
       return compareNumberProtos(left, right);
     case TypeOrder.TIMESTAMP:

dev/system-test/firestore.ts

@@ -4084,6 +4084,36 @@ describe('Query class', () => {
         docChanges: expectedChanges,
       });
     });
+
+    it('snapshot listener sorts query by unicode strings same way as server', async () => {
+      const collection = await testCollectionWithDocs({
+        a: {value: 'Łukasiewicz'},
+        b: {value: 'Sierpiński'},
+        c: {value: '岩澤'},
+        d: {value: '🄟'},
+        e: {value: 'Ｐ'},
+        f: {value: '︒'},
+        g: {value: '🐵'},
+      });
+
+      const query = collection.orderBy("value");
+      const expectedDocs = ['b', 'a', 'c', 'f', 'e', 'd', 'g'];
+
+      const getSnapshot = await query.get();
+      expect(getSnapshot.docs.map(d => d.id)).to.deep.equal(expectedDocs);
+
+      const unsubscribe = query.onSnapshot(snapshot =>
+        currentDeferred.resolve(snapshot)
+      );
+
+      const watchSnapshot = await waitForSnapshot();
+      // Compare the snapshot (including sort order) of a snapshot
+      snapshotsEqual(watchSnapshot, {
+        docs: getSnapshot.docs,
+        docChanges: getSnapshot.docChanges(),
+      });
+      unsubscribe();
+    });
   });
 
   (process.env.FIRESTORE_EMULATOR_HOST === undefined