import com.mongodb.ConnectionString
import com.mongodb.MongoClientSettings
import com.mongodb.client.model.Filters
import com.mongodb.event.CommandListener
import com.mongodb.event.CommandStartedEvent
import com.mongodb.event.CommandSucceededEvent
import com.mongodb.kotlin.client.coroutine.MongoClient
import kotlinx.coroutines.flow.toList
import kotlinx.coroutines.test.runTest
import org.bson.BsonInt64
import org.bson.Document
import org.junit.jupiter.api.Assertions.assertAll
import org.junit.jupiter.api.Assertions.assertEquals
import org.junit.jupiter.api.Assertions.assertTrue
import org.junit.jupiter.api.Test
import java.util.UUID

class MongoTest() {

    @Test
    fun `should run only one getMore`() = runTest {
        val randomDatabase = UUID.randomUUID().toString()
        val listener = Listener(mutableListOf(), mutableListOf())
        val clientSettings = MongoClientSettings.builder()
            .applyConnectionString(ConnectionString("mongodb://127.0.0.1:27017"))
            .commandListenerList(listOf(listener))
            .build()
        val database = MongoClient.create(clientSettings).getDatabase(databaseName = randomDatabase)
        database.runCommand(Document("ping", BsonInt64(1)))
        val collection = database.getCollection<Document>("test-collection")
        assertTrue(collection.insertMany(List(200) { Document() }).wasAcknowledged())

        assertEquals(200, collection.find(Filters.empty()).toList().size)

        // first find should return 101 documents, the getMore should return the remaining ones
        assertAll(
            { assertEquals(listOf("ping", "insert", "find", "getMore"), listener.commands) },
            { assertEquals(listOf("find" to 101, "getMore" to -1), listener.batchSizes) },
        )
    }

    class Listener(
        val commands: MutableList<String>,
        val batchSizes: MutableList<Pair<String, Int>>,
    ) : CommandListener {
        override fun commandStarted(event: CommandStartedEvent) {
            if (event.commandName in setOf("find", "getMore")) {
                val batchSize = event.command["batchSize"]?.asInt32()?.value ?: -1
                batchSizes.add(event.commandName to batchSize)
            }
        }

        override fun commandSucceeded(event: CommandSucceededEvent) {
            commands.add(event.commandName)
        }
    }
} 

org.opentest4j.AssertionFailedError: 
Expected :[ping, insert, find, getMore]
Actual   :[ping, insert, find, getMore, getMore, getMore]
...
org.opentest4j.AssertionFailedError: 
Expected :[(find, 101), (getMore, -1)]
Actual   :[(find, 64), (getMore, 64), (getMore, 64), (getMore, 64)]