### Question:
OssStorageResource implements WritableResource { @Override public long lastModified() throws IOException { assertExisted(); if (isBucket()) { throw new FileNotFoundException("OSSObject not existed."); } return getOSSObject().getObjectMetadata().getLastModified().getTime(); } OssStorageResource(OSS oss, String location,
                              ConfigurableListableBeanFactory beanFactory);  OssStorageResource(OSS oss, String location,
                              ConfigurableListableBeanFactory beanFactory, boolean autoCreateFiles); boolean isAutoCreateFiles(); @Override boolean exists(); @Override URL getURL(); @Override URI getURI(); @Override File getFile(); @Override long contentLength(); @Override long lastModified(); @Override Resource createRelative(String relativePath); @Override String getFilename(); @Override String getDescription(); @Override InputStream getInputStream(); Bucket getBucket(); boolean bucketExists(); OSSObject getOSSObject(); boolean isBucket(); Bucket createBucket(); @Override boolean isWritable(); @Override OutputStream getOutputStream();  }### Answer:
@Test public void testBucketLastModified() throws IOException { this.expectedEx.expect(FileNotFoundException.class); this.expectedEx.expectMessage("OSSObject not existed."); this.bucketResource.lastModified(); }