assert_files_exist(['test1', 'test2'])
os.utime('test2', (0, 0))
assert os.system("remove-old-files.py --older 100 .") == 0
assert_files_exist(['test1', 'test2'])
os.utime('test2', (0, 0))
assert os.system("remove-old-files.py --older 100 .") == 0
assert_files_exist([test3, test4])
os.utime(test4, (0, 0))
assert os.system("remove-old-files.py --older 100 .") == 0
assert_files_exist([test3, test4])
os.utime(test4, (0, 0))
assert os.system("remove-old-files.py --older 100 .") == 0