kotlinx.fuzz allows user to enable logs during the fuzzing campaign. It uses SLF4J API to implement logging and can use user-provided SLF4J implementation to output the logs. If there are no SLF4J implementations provided, kotlinx.fuzz uses its custom logging implementation to output all the debugging info to standard output.
By default kotlinx.fuzz outputs only WARN or more severe messages, however this behaviour can be configured through logLevel property in the fuzzConfig or through "kotlinx.fuzz.log.level" system property.
Additionally, kotlinx.fuzz saves all the output/logs of the fuzzing engine. They are saved in the "$workDir/logs" directory, individually for each fuzz test. Additionally, user can enable printing of the Jazzer logs to standard output through enableLogging configuration option or "kotlinx.fuzz.jazzer.enableLogging" system property.