feat: add MongoDB 5.1 compatibility (#7682)

spec/MongoStorageAdapter.spec.js

@@ -308,7 +308,7 @@ describe_only_db('mongo')('MongoStorageAdapter', () => {
     await expectAsync(adapter.getClass('UnknownClass')).toBeRejectedWith(undefined);
   });
 
-  it('should use index for caseInsensitive query', async () => {
+  it_only_mongodb_version('<5.1')('should use index for caseInsensitive query', async () => {
     const user = new Parse.User();
     user.set('username', 'Bugs');
     user.set('password', 'Bunny');
@@ -342,6 +342,40 @@ describe_only_db('mongo')('MongoStorageAdapter', () => {
     expect(postIndexPlan.executionStats.executionStages.stage).toBe('FETCH');
   });
 
+  it_only_mongodb_version('>=5.1')('should use index for caseInsensitive query', async () => {
+    const user = new Parse.User();
+    user.set('username', 'Bugs');
+    user.set('password', 'Bunny');
+    await user.signUp();
+
+    const database = Config.get(Parse.applicationId).database;
+    await database.adapter.dropAllIndexes('_User');
+
+    const preIndexPlan = await database.find(
+      '_User',
+      { username: 'bugs' },
+      { caseInsensitive: true, explain: true }
+    );
+
+    const schema = await new Parse.Schema('_User').get();
+
+    await database.adapter.ensureIndex(
+      '_User',
+      schema,
+      ['username'],
+      'case_insensitive_username',
+      true
+    );
+
+    const postIndexPlan = await database.find(
+      '_User',
+      { username: 'bugs' },
+      { caseInsensitive: true, explain: true }
+    );
+    expect(preIndexPlan.queryPlanner.winningPlan.queryPlan.stage).toBe('COLLSCAN');
+    expect(postIndexPlan.queryPlanner.winningPlan.queryPlan.stage).toBe('FETCH');
+  });
+
   it('should delete field without index', async () => {
     const database = Config.get(Parse.applicationId).database;
     const obj = new Parse.Object('MyObject');