Major - P3 I apologize if this is not a bug and merely a misunderstanding of the spec/implementation on my part, but I am hoping to at least get clarification on a possible inconsistency I have noticed while doing some chaos testing against a replicaSet.
According to this table in the SDAM spec , when a topology of type ReplicaSetNoPrimary receives a server of type Unknown the driver should update the description and do nothing. However, in lib/core/sdam/topology_description.js#L192|https://github.com/mongodb/node-mongodb-native/blob/next/lib/core/sdam/topology_description.js#L192] it appears that the driver opts to remove Unknown servers from the topology description.