mockito-inline causes logback classic to throw NullPointerException: Cannot read the array length because "throwableSuppressed" is null

Question

Just switching from mockito-core to mockito-inline (4.11.0), without any code changes, causes logback-classic (1.2.11) to throw

Caused by: java.lang.NullPointerException: Cannot read the array length because "throwableSuppressed" is null
  at ch.qos.logback.classic.spi.ThrowableProxy.<init>(ThrowableProxy.java:99)
  at ch.qos.logback.classic.spi.ThrowableProxy.<init>(ThrowableProxy.java:62)
  at ch.qos.logback.classic.spi.LoggingEvent.<init>(LoggingEvent.java:119)
  at ch.qos.logback.classic.Logger.buildLoggingEventAndAppend(Logger.java:419)
  at ch.qos.logback.classic.Logger.filterAndLog_0_Or3Plus(Logger.java:383)
  at ch.qos.logback.classic.Logger.warn(Logger.java:704)

the log line is

      LOG.warn(
          "{} while registering RIC {}, will retry once: {}",
          oe.getClass().getSimpleName(), ric, oe.toString(), oe);

Any ideas how to fix this?

Changing the args to oe.getClass().getSimpleName(), ric, oe.toString() works around the issue but you loose the stacktrace in the logs, and I'd hate to loose that in production just to work around an issue in the tests.

Changing the args to oe.getClass().getSimpleName(), ric, oe
or oe.getClass().getSimpleName(), ric, oe, oe
does not work.

You have to show your mock setup and your stubbings. [edit] your question to include a [mwe]. — knittl, Aug 16 '23 at 16:10

score 0 · Answer 1 · answered Aug 16 '23 at 16:17

The answer involves the fact that it is a mocked exception (which I have to do because the exception I need is from a 3rd party library and they don't expose a way to create a real one).

With mockito-core and no explicit mocking of the getSuppressed() method it returns Throwable[0]
but with mockito-inline it returns null.

I am certainly surprised that just changing that dependency affects what is returned by default there, but it can be solved by explicitly mocking it out like

    lenient().when(e.getSuppressed()).thenReturn(new Throwable[0]);

mockito-inline causes logback classic to throw NullPointerException: Cannot read the array length because "throwableSuppressed" is null

1 Answers1