description: server selection for load-balanced clusters

schemaVersion: '1.3'

runOnRequirements:
  - topologies: [ load-balanced ]

createEntities:
  - client:
      id: &client0 client0
      useMultipleMongoses: true
      observeEvents:
        - commandStartedEvent
  - database:
      id: &database0 database0
      client: *client0
      databaseName: &database0Name database0Name
  - collection:
      id: &collection0 collection0
      database: *database0
      collectionName: &collection0Name coll0
      collectionOptions:
        readPreference:
          # Use secondaryPreferred to ensure that operations can succeed even if the shards are only comprised of one
          # server.
          mode: &readPrefMode secondaryPreferred

initialData:
  - collectionName: *collection0Name
    databaseName: *database0Name
    documents: []

tests:
  - description: $readPreference is sent for load-balanced clusters
    operations:
      - name: find
        object: *collection0
        arguments:
          filter: {}
    expectEvents:
      - client: *client0
        events:
          - commandStartedEvent:
              command:
                find: *collection0Name
                filter: {}
                $readPreference:
                  mode: *readPrefMode
              commandName: find
              databaseName: *database0Name