How to re-initialize the Spring Boot Logging System in a Spring Boot 2.4 Test

ReinitializingLoggingSystemTest.kt

@SpringBootTest
@TestPropertySource(properties = ["logging.config=classpath:logback-other.xml"])
@ContextConfiguration(initializers = [LoggingSystemReinitializer::class])
class LoggingMaskingDecoratorTest {
  
  private val standardOut = System.out
  private val outputStreamCaptor: ByteArrayOutputStream = ByteArrayOutputStream()

  companion object {
        @AfterAll
        @JvmStatic
        fun cleanupLoggingSystem() {
            val system = LoggingSystem.get(LoggingSystem::class.java.classLoader)
            system.cleanUp()
        }
    }
  
    @BeforeEach
    fun setUp() {
        System.setOut(PrintStream(outputStreamCaptor))
    }

    @AfterEach
    fun tearDown() {
        System.setOut(standardOut)
    }

    @Test
    fun `should log something`() {
      val logger = LoggerFactory.getLogger("MyLogger")

      logger.info("Some Logging")

      val output = outputStreamCaptor.toString().trim { it <= ' ' }
      assertThat(output).contains("Some Logging")
    } 
}


class LoggingSystemReinitializer : ApplicationContextInitializer<ConfigurableWebApplicationContext> {
    override fun initialize(context: ConfigurableWebApplicationContext) {
        val environment = context.environment
        val logConfig = environment.getProperty(CONFIG_PROPERTY)
        if (logConfig != null) {
            val system = LoggingSystem.get(LoggingSystem::class.java.classLoader)
            system.cleanUp()
            try {
                system.initialize(LoggingInitializationContext(environment), logConfig, LogFile.get(environment));
            } catch (e: Exception) {
                throw RuntimeException("Unable to reinitialize LoggingSystem: ", e)
            }
        }
    }
}