Mongoose.connection.collections.collection.drop () throws error every time

I am setting up testing with Jest for a Node / Express / Mongo project. I tried to write a function to clean up collections, so every test starts from scratch:

const clearCollection = (collectionName, done) => {
  const collection = mongoose.connection.collections[collectionName]
  collection.drop(err => {
    if (err) throw new Error(err)
    else done()
  )
}

beforeEach(done => {
  clearCollection('users', done)
})

      

        
        
        
      

    

And one more try: promises:

const clearCollection = collectionName => {
  const collection = mongoose.connection.collections[collectionName]
  return collection.drop()
}

beforeEach(async () => {
  await clearCollection('users')
})

      

        
        
        
      

    

The problem is they both alternate between work and error. Every time I save the file it either works fine or generates an error alternating each time. Errors are always either one of:

MongoError: cannot perform operation: a background operation is currently running for collection auth_test.users

MongoError: ns not found

      

        
        
        
      

    

I can get it to work 100% of the time (limited by the stack anyway) by creating a clearCollection()

call inside catch()

, but it seems so wrong:

const clearCollection = collectionName => {
  const collection = mongoose.connection.collections[collectionName]
  return collection.drop()
    .catch(() => clearCollection(collectionName))
}