Mongodb Node.js Deleteone Via _id Doesn't Work On Objectid

I'm trying to write test (spec) on a mongo DB wrapper and stumbled on this weird issue. My code, build on top of a thin wrapper of mongodb, expose _id as string to the world but us

Solution 1:

Are you sure your fixtures aren't mangled between different tests?

And by the way shouldn't

return MongoDb.ObjectId(id);

be

return new MongoDb.ObjectId(id);

?