test_posix.py 文件源码

def test_fs_holes(self):
        # Even if the filesystem doesn't report holes,
        # if the OS supports it the SEEK_* constants
        # will be defined and will have a consistent
        # behaviour:
        # os.SEEK_DATA = current position
        # os.SEEK_HOLE = end of file position
        with open(support.TESTFN, 'r+b') as fp:
            fp.write(b"hello")
            fp.flush()
            size = fp.tell()
            fno = fp.fileno()
            try :
                for i in range(size):
                    self.assertEqual(i, os.lseek(fno, i, os.SEEK_DATA))
                    self.assertLessEqual(size, os.lseek(fno, i, os.SEEK_HOLE))
                self.assertRaises(OSError, os.lseek, fno, size, os.SEEK_DATA)
                self.assertRaises(OSError, os.lseek, fno, size, os.SEEK_HOLE)
            except OSError :
                # Some OSs claim to support SEEK_HOLE/SEEK_DATA
                # but it is not true.
                # For instance:
                # http://lists.freebsd.org/pipermail/freebsd-amd64/2012-January/014332.html
                raise unittest.SkipTest("OSError raised!")