Kotlin Asserting Log Messages With JUnit

MemoryAppender.kt

package ru.mts.ftb.ftbotpservice.utils

import ch.qos.logback.classic.Level
import ch.qos.logback.classic.spi.ILoggingEvent
import ch.qos.logback.core.read.ListAppender

//inspired by https://www.baeldung.com/junit-asserting-logs
class MemoryAppender : ListAppender<ILoggingEvent?>() {
    fun reset() = list.clear()

    fun contains(level: Level, string: String): Boolean = list.any {
        it?.message.toString().contains(string) && it?.level == level
    }

    fun countEventsForLogger(loggerName: String): Int = list.count {
            it?.loggerName?.contains(loggerName) == true
        }

    fun search(string: String): List<ILoggingEvent> = list.asSequence().filter {
        it?.message.toString().contains(string)
    }.filterNotNull().toList()

    fun search(level: Level, string: String): List<ILoggingEvent> = list.asSequence().filter {
        it?.message.toString().contains(string) && it?.level == level
    }.filterNotNull().toList()

    fun getSize(): Int = list.size

    fun getLoggedEvents(): List<ILoggingEvent?> = list.toList()
}