Merge pull request #14277 from Automattic/vkarpov15/gh-14184

fix(collection): correctly handle buffer timeouts with `find()`

lib/drivers/node-mongodb-native/collection.js

@@ -138,10 +138,23 @@ function iter(i) {
       let _args = args;
       let promise = null;
       let timeout = null;
-      if (syncCollectionMethods[i]) {
-        this.addQueue(() => {
-          lastArg.call(this, null, this[i].apply(this, _args.slice(0, _args.length - 1)));
-        }, []);
+      if (syncCollectionMethods[i] && typeof lastArg === 'function') {
+        this.addQueue(i, _args);
+        callback = lastArg;
+      } else if (syncCollectionMethods[i]) {
+        promise = new this.Promise((resolve, reject) => {
+          callback = function collectionOperationCallback(err, res) {
+            if (timeout != null) {
+              clearTimeout(timeout);
+            }
+            if (err != null) {
+              return reject(err);
+            }
+            resolve(res);
+          };
+          _args = args.concat([callback]);
+          this.addQueue(i, _args);
+        });
       } else if (typeof lastArg === 'function') {
         callback = function collectionOperationCallback() {
           if (timeout != null) {

test/collection.test.js

@@ -68,6 +68,19 @@ describe('collections:', function() {
     });
   });
 
+  it('returns a promise if buffering and callback with find() (gh-14184)', function(done) {
+    db = mongoose.createConnection();
+    const collection = db.collection('gh14184');
+    collection.opts.bufferTimeoutMS = 100;
+
+    collection.find({ foo: 'bar' }, {}, (err, docs) => {
+      assert.ok(err);
+      assert.ok(err.message.includes('buffering timed out after 100ms'));
+      assert.equal(docs, undefined);
+      done();
+    });
+  });
+
   it('methods should that throw (unimplemented)', function() {
     const collection = new Collection('test', mongoose.connection);
     let thrown = false;