### Question:
CacheStorageFiles { static boolean isLayerFile(Path file) { return file.getFileName().toString().length() == DescriptorDigest.HASH_LENGTH; } CacheStorageFiles(Path cacheDirectory);   }### Answer:
@Test public void testIsLayerFile() { Assert.assertTrue( CacheStorageFiles.isLayerFile( Paths.get("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"))); Assert.assertTrue( CacheStorageFiles.isLayerFile( Paths.get("bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"))); Assert.assertFalse(CacheStorageFiles.isLayerFile(Paths.get("is.not.layer.file"))); }