client = Mongo::Client.new(["localhost:27017"])
102.times do |i|
   client[:test].insert_one(a: i)  
end
client[:test].find({}, limit: 0).to_a

DEBUG -- : MONGODB | localhost:27017 | admin.find | STARTED | {"find"=>"test", "filter"=>{}, "limit"=>0}
DEBUG -- : MONGODB | localhost:27017 | admin.find | SUCCEEDED | 0.0021939999999999998s
DEBUG -- : MONGODB | localhost:27017 | admin.getMore | STARTED | {"getMore"=>15001859357, "collection"=>"test", "batchSize"=>0}
DEBUG -- : MONGODB | localhost:27017 | admin.getMore | FAILED | Batch size for getMore must be positive, but received: 0 (2) | 0.00036199999999999996s
Mongo::Error::OperationFailure: Batch size for getMore must be positive, but received: 0 (2)
from /Users/emily/Code/driver/mongo-ruby-driver/lib/mongo/operation/result.rb:256:in `validate!'