Schema format cleanup

src/Adapters/Storage/Mongo/MongoSchemaCollection.js

@@ -115,9 +115,20 @@ class MongoSchemaCollection {
     });
   }
 
+  // Add a collection. Currently the input is in mongo format, but that will change to Parse format in a
+  // later PR. Returns a promise that is expected to resolve with the newly created schema, in Parse format.
+  // If the class already exists, returns a promise that rejects with undefined as the reason. If the collection
+  // can't be added for a reason other than it already existing, requirements for rejection reason are TBD.
   addSchema(name: string, fields) {
     let mongoObject = _mongoSchemaObjectFromNameFields(name, fields);
-    return this._collection.insertOne(mongoObject);
+    return this._collection.insertOne(mongoObject)
+    .then(result => mongoSchemaToParseSchema(result.ops[0]))
+    .catch(error => {
+      if (error.code === 11000) { //Mongo's duplicate key error
+        return Promise.reject();
+      }
+      return Promise.reject(error);
+    });
   }
 
   updateSchema(name: string, update) {