NullPointer Check fails when used with Testcontainers

[idotobi]

When trying to setup testcontainers in a project I ran into a problem with slf4j-test.

It seems that while testcontainers starts a container it creates a log event with the message being null.
This causes the check in line 409

slf4j-test/src/main/java/com/github/valfirst/slf4jtest/LoggingEvent.java

Lines 395 to 409 in 9eeddda

	LoggingEvent(
	final Optional<TestLogger> creatingLogger,
	final Level level,
	final Map<String, String> mdc,
	final Optional<Marker> marker,
	final Optional<Throwable> throwable,
	final String message,
	final Object... arguments) {
	super();
	this.creatingLogger = creatingLogger;
	this.level = checkNotNull(level);
	this.mdc = ImmutableMap.copyOf(mdc);
	this.marker = checkNotNull(marker);
	this.throwable = checkNotNull(throwable);
	this.message = checkNotNull(message);

to fail with the following stacktrace:

Caused by: java.lang.NullPointerException
	at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:889)
	at com.github.valfirst.slf4jtest.LoggingEvent.<init>(LoggingEvent.java:409)
	at com.github.valfirst.slf4jtest.TestLogger.addLoggingEvent(TestLogger.java:448)
	at com.github.valfirst.slf4jtest.TestLogger.log(TestLogger.java:432)
	at com.github.valfirst.slf4jtest.TestLogger.log(TestLogger.java:409)
	at com.github.valfirst.slf4jtest.TestLogger.debug(TestLogger.java:170)
	at org.testcontainers.images.builder.ImageFromDockerfile$1.onNext(ImageFromDockerfile.java:106)
	at org.testcontainers.images.builder.ImageFromDockerfile$1.onNext(ImageFromDockerfile.java:98)
	at org.testcontainers.shaded.com.github.dockerjava.core.exec.AbstrAsyncDockerCmdExec$1.onNext(AbstrAsyncDockerCmdExec.java:41)
	at org.testcontainers.shaded.com.github.dockerjava.core.DefaultInvocationBuilder$JsonSink.accept(DefaultInvocationBuilder.java:315)
	at org.testcontainers.shaded.com.github.dockerjava.core.DefaultInvocationBuilder$JsonSink.accept(DefaultInvocationBuilder.java:298)
	at org.testcontainers.shaded.com.github.dockerjava.core.DefaultInvocationBuilder.lambda$executeAndStream$1(DefaultInvocationBuilder.java:275)
	at java.base/java.lang.Thread.run(Thread.java:833)

When I remove slf4j-test as a dependency the container starts up as expected.
Since I would expect the presence of slf4j-test not to have any impact on the general flow of a program I think this might be a bug in slf4j-test rather than testcontainers but you can judge this better than me 😅 .

[valfirst]

@idotobi could you please provide Short, Self Contained, Correct (Compilable), Example to reproduce the issue?

[josephw]

Reproduction is fairly simple:

import org.slf4j.LoggerFactory;

public class LogNullTest {
    public static void main(String[] args) {
        LoggerFactory.getLogger(LogNullTest.class).info(null);
    }
}

with slf4j-test causes:

java.lang.NullPointerException
	at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:878)
	at com.github.valfirst.slf4jtest.LoggingEvent.<init>(LoggingEvent.java:409)

whereas (e.g.) slf4j-simple logs:

[main] INFO LogNullTest - null

This seems like a bug in testcontainers, but other implementations accept it, and the SLF4J documentation for Logger doesn't specify whether or not null can be passed.