StackTraceCleaner does not handle infinite cause chains

[dsommerich]

Example

import com.google.common.truth.Truth;
import org.junit.jupiter.api.Test;

public class TruthTest {
    @Test
    void test() {
        Truth.assertThat(new EvilThrowable()).isSameInstanceAs(new RuntimeException());
    }

    static class EvilThrowable extends Throwable {
        @Override
        public synchronized Throwable getCause() {
            return new EvilThrowable();
        }
    }
}

This example does not terminate, it just spins forever.

I beleive this is because StackTraceCleaner does not implement any kind of hard limit (which is the only way I can think of of how to fix this).

I know this is a very specific edge case, it came up while trying to test code that does a similar thing (traverse a Throwable's causes) with a malicious/very broken implementation of a Throwable.

[cpovirk]

That is indeed pretty evil, thanks :)

As a workaround, you can pass -Dcom.google.common.truth.disable_stack_trace_cleaning=true to the JVM when running your test. However, I wonder if you'll then see a failure when your test runner tries to output the exception :) But maybe it will at least overflow the stack and terminate, rather than hanging?

We may try to have a look "eventually." I guess it's at least reasonably straightforward to set a hard limit, as you say.