Optionals not recognized after extracting, and also not working as extracting parameter

[Philzen]

I am experimenting with https://github.com/Hakky54/log-captor for a migration. Now i'm stumbling over the extraction of Optionals.

The method LogEvent::getThrowable returns an Optional<Throwable> which i would expect to be able to either extract during the assertJ chain like in example (4) below, or even better which would be resolved on-the-fly as in example (3), although i understand that may be a breaking change for some people. Maybe there's a smarter way auto-get the content of the Optional which i haven't discovered in the AssertJ docs yet, always grateful for advice.

The gist is, i'd really like to be able to use .first() in the fluent assertion, but the assertion chain seems to break as soon as i try that.

        // Works
        assertThat(logCaptor.getLogEvents().get(0).getThrowable()).isPresent().get(THROWABLE)
            .isExactlyInstanceOf(NullPointerException.class).hasNoCause();

        // Works
        assertThat(logCaptor.getLogEvents().get(0).getThrowable().isPresent()).isTrue();
        assertThat(logCaptor.getLogEvents().get(0).getThrowable().get())
            .isExactlyInstanceOf(NullPointerException.class).hasNoCause();

        // Fails: Instance of Optional instead of NullPointerException (kind of makes sense)
        assertThat(logCaptor.getLogEvents())
            .first().extracting(LogEvent::getThrowable)
            .isExactlyInstanceOf(NullPointerException.class);

        // Fails: Still instance of Optional instead of NullPointerException (!?)
        assertThat(logCaptor.getLogEvents())
            .first().extracting(LogEvent::getThrowable).extracting(Optional::get)
            .isExactlyInstanceOf(NullPointerException.class);

        // not possible (?!)
        assertThat(logCaptor.getLogEvents()).first().extracting(LogEvent::getThrowable)
            .isPresent(); // would like to continue here like in the first working example, but won't compile

• assertj core version: 3.24.2
• java version: 11.0.20.1-tem
• test framework version: JUnit 5.8.2

[joel-costigliola]

Thanks for reporting this @Philzen, could you provide a minimal reproducible test so that we can try on our side?
I'm especially in case 4 which should be an instance of a Throwable.

Have you tried using extracting with a lambda that is not a method reference, so instead of

extracting(LogEvent::getThrowable).extracting(Optional::get)

you would use:

extracting(logEvent -> logEvent .getThrowable().get())

[scordio]

If I understood your requirement correctly, you could try the following:

assertThat(logCaptor.getLogEvents())
  .first(InstanceOfAssertFactories.type(LogEvent.class))
  .extracting(LogEvent::getThrowable, InstanceOfAssertFactories.OPTIONAL)
  .get(InstanceOfAssertFactories.THROWABLE) // isPresent() called implicitly
  .isExactlyInstanceOf(NullPointerException.class)
  .hasNoCause();

or less verbose, if giving up a bit of type-safety is an option:

assertThat(logEvents)
  .first()
  .extracting("throwable.value", THROWABLE)
  .isExactlyInstanceOf(NullPointerException.class)
  .hasNoCause();

(static imports omitted for clarity)