code: @Test public void withFile() throws Exception {
    File temp=new File(tmpDir());
    File[] logFiles=temp.listFiles(SPRING_LOG_FILTER);
    for (  File file : logFiles) {
      file.delete();
    }
    this.loggingSystem.beforeInitialize();
    this.logger.info("Hidden");
    this.loggingSystem.initialize(null,tmpDir() + "/spring.log");
    this.logger.info("Hello world");
    String output=this.output.toString().trim();
    assertTrue("Wrong output:\n" + output,output.contains("Hello world"));
    assertFalse("Output not hidden:\n" + output,output.contains("Hidden"));
    assertThat(temp.listFiles(SPRING_LOG_FILTER).length,greaterThan(0));
  }
  