code: public void testFileDeletion  ( ) throws Exception  { File testDir = createTestDir ( "testFileDeletion" ) ; String prefix1 = "testFileDeletion1" ; File [ ] files1 = createFiles ( testDir , prefix1 , 5 ) ; String prefix2 = "testFileDeletion2" ; File [ ] files2 = createFiles ( testDir , prefix2 , 5 ) ; FileCommands . deleteFiles ( files1 , true ) ; assertNotExists ( files1 ) ; FileCommands . deleteFiles ( files2 , false ) ; Thread . sleep ( 1000 ) ; assertNotExists ( files2 ) ; }