testkit/src/test/resources/logback-test.xml

<?xml version="1.0" encoding="utf-8"?>
<configuration>
    <!-- Silence initial setup logging from Logback -->
    <statusListener class="ch.qos.logback.core.status.NopStatusListener" />
    <appender name="STDOUT" target="System.out" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>[%date{ISO8601}] [%level] [%logger] [%marker] [%thread] - %msg MDC: {%mdc}%n</pattern>
        </encoder>
    </appender>

    <appender name="CapturingAppender" class="org.apache.pekko.actor.testkit.typed.internal.CapturingAppender" />

    <logger name="org.apache.pekko.actor.testkit.typed.internal.CapturingAppenderDelegate" >
        <appender-ref ref="STDOUT"/>
    </logger>

    <root level="DEBUG">
        <appender-ref ref="CapturingAppender" />
    </root>
</configuration>