Capturing log4j messages for a unit test

CapturingLog4jMessagesForAUnitTest

    @Test
    void loggingCaptureTest() {
        final var log = (org.apache.logging.log4j.core.Logger)LogManager.getLogger(Foobar.class); // whatever you use to get a logger

        CharArrayWriter outContent = new CharArrayWriter();
        StringLayout layout = PatternLayout.newBuilder().withPattern("%-5level %msg").build();
        Appender appender = WriterAppender.newBuilder().setTarget(outContent).setLayout(layout).setName("TEST").build();
        appender.start();
        log.addAppender(appender);
        log.setLevel(Level.DEBUG);

        log.info("foo {}", "bar");

        log.removeAppender(appender);
        var msg = outContent.toString();
        assertThat(msg).isEqualTo("INFO  foo bar");
    }

This is for log4j 2.17.2.